This video is the most important information I’ve ever seen for flying twins. As a multi-engine flight instructor and survey pilot, I think this video should be a must watch for every pilot of a twin.
I appreciate your response Ibrahim, it means that the subject keeps you busy and you obviously want to prevent accidents. Turning to either side, while an engine is inoperative, increases the sideslip angle and hence, the drag. The single engine climb performance at low speed is only maximal during straight flight and while also a small bank angle into the good engine of 5° is being maintained at Vmc (Vmca), or 3° at Vyse, or smaller when the airspeed is higher. This is a consequence, for pilots an operational maneuver limitation, of the FAA and EASA approved airplane tail design criteria (in FAR/CS 23.149 and 25.149). On most small twins you will not have a positive Rate of Climb at all when banking away from the favorable small bank angle. Don't forget that the asymmetrical thrust does not decrease during a turn and needs to be counteracted whatever the turn direction and airspeed. Lots of variables here! Please refer to a paper I wrote on these subjects, in which turns are also discussed and graphs are presented showing sideslip during banking, and where you also can find answers: www.avioconsult.com/downloads.htm#Investigators.
Thanks for your comment. It supports the conclusion that control after engine failure, and therewith the appreciation of the real value of Vmca, got less and less attention during the past 40 - 50 years. I've old DC-8-63 and current C-130 manuals, besides Test Pilot School manuals, that present the right stuff on the subject. Most FI's and authorities who I talked to, told me "never heard of it, cannot be right what you're saying" (they are younger than you and I). How do we get to teach all multi-engine pilots the real value of Vmca again, and the do's and don'ts that come with it? Pilots (and their pax) don't want to get killed, do they?
I am in the process of obtaining my MEI and appreciate the thorough explanation. I want to be safe and teach safety with understanding. My take away is 1) speed, 2) 3-5 degrees aileron, rudder ( for straight flight, then cage the engine. Thank you so much. I too will share this with my ME students.
Spot-on Harry! I'm currently flying large, transport category jets, but am about to get back into light twin flying and instruction. I happened upon you outstanding video while studying. Very good food for thought and thank you so much for taking the time to make this presentation. Dank je.
I regret very much that this accident happened; my sincere condolences to the families who lost loved ones. The accident is very similar to the EMB-120 accident in the video. Loss of control, even when the airspeed was V2. This proves that V2 is not a safe takeoff safety speed. This ATR72 accident should not have happened; proper limitations are in place (in flight and ops manuals) but are regrettably not understood anymore by airline pilots. I do not blame the pilots, but do blame the authorities in the USA (FAA and NTSB), in Australia (ATSB and CASA) and in the Netherlands to whom I wrote letters and e-mails many years ago telling that airline pilots operate their airplanes after engine failure in a way that is definitely neither in agreement with the limitations that are the consequence of the design/ sizing process of the vertical tail of multi-engine airplanes, nor with the way that the minimum control speeds are determined by experimental test pilots and flight test engineers, who are graduate of one of the few test pilot schools. These authorities do not understand this either. The oldest Flight Manual that was right on this subject I've seen is a DC-8-63 manual, 50 years ago. Thereafter the proper knowledge faded away (except at Test Pilot Schools). All engine-out airspeed limitations (Vmca, V2min) are valid only while maintaining straight flight, that is while banking a few, up to 5 degrees, away from the inoperative engine. The manufacturer should specify the exact number of degrees, but the FAA and EASA do not require this. I wish somebody could send me a pdf copy of a few pages out of the ATR72 AFM with Vmca and V2 definitions, engine emergency procedures and one engine inoperative performance data tables/graphs, to analyze and review and let the world know whether these are right for this airplane. No pilot wants to get killed due to inappropriate manuals, I'm sure. I can help and will publish the result on my website avioconsult.com. On the downloads and accident pages are many papers available. Fly safely.
When banking into the good engine, the sideforce due to weight, that acts in the cg, increases to the good engine side. It is easier to see this while working in the body-axes system, the lateral axis of which runs from wing tip to wingtip throught the cg. Because of this increasing sideforce, the airplane starts sideslipping into the good engine until the opposite side force due to the sideslip is increased large enough to counteract the sideforce due to banking in the cg. A rudder sideforce to the dead engine side remains required to counteract the thrust yawing moment which adds to the banking sideforce. The fin and rudder can only generate this higher required opposite side force if the airspeed is higher (the force is proportional to V squared). The minimum speed for maintaining equilibrium of forces and moments when banking into the good engine is higher or, in other words, the actual Vmc is higher. If the airspeed is, or decreases below this higher required airspeed, the equilibrium of side forces and yawing moments cannot be maintained and the airplane continues to sideslip and, if the altitude is low, flies into terrain. If you need to learn more, please review thisTest Pilot School course: www.dtic.mil/dtic/tr/fulltext/u2/a319982.pdf.
As a pilot and aeronautical engineer myself, I found this video very interesting. I have dealt with both the CS 25 and airplane flight manuals, these documents are essentially very different and it shouldn´t be the pilots job to interpret or understand the certification specifications. One note however on slide 34 (39:00), with Vto I assume you mean rotation speed Vr? My understanding of Vto is this is the lift-off speed, the speed at which the entire aircraft just lifts off the ground and it is of no operational significance.
This is an eye opening presentation. I'm sure there was probably discussion about Vmca changing under different conditions when I started flying twins and bought my Baron 20 years ago but there were no charts quantifying it and the conditions that change it the way you have done here. I think the normal curriculum has been over simplified (dumbed down) to give new pilots easy to remember simple rules that marketing folks need to make the aircraft seem more versatile. This presentation has given me pretty specific things to think about in my SOP. What are your thoughts on VG's lowering the Vmca? Would the improvement be proportional through the different scenarios that you describe? Thanks.
Yes, now its evident: on takeoff with the usual required high AOA, if the nose starts an un commanded/ unexpected yaw say to left, the automatic reaction might be compensate with yoke/aeleron to the right with the wrong assumption that the plane is turning rather than yawing. But if left engine is failing that could be fatal as the lowered left aileron flap now increases the AOA on tht side aggravating the situation. The answer is immediately lower the nose to increase speed and reduce AOA and right rudder and select safe heading to track to prevent the uncommanded turn thats a actually due to yawing from reduced thrust on that side. When in doubt use rudder and reduce AOA until can clarify why the yaw/turn was occuring. Aileron needs to be used secondarily not primary. Also must demand traffic pattern with gentle turns to the good engine, his lecture makes it clear that even normal bank angles on the bad side can cause sudden loss of control as VMC can drastically increase with bank angle and the bad part is there would be no real-time warning by the systems as to the impending fatally reduced margin of error wrt speed management.
When I was getting my multi engine rating 37 years ago my instructor made me experience this loss of control at 5000 feet above ground and allowed the plane the completely roll over and note the speed when it began Beech Baron e55. In that experience I never forgot how useless the controls were. and I always took it upon myself to practice whenever got the chance.
That was just plain stupid and reckless by your instructor. A high asymmetrical Vmca roll in any twin that is allowed to fully develop into loss of control is about as dumb an intentional maneuver you can do. You are lucky you are not dead. Do a google search on that, especially in Barons, which have a propensity to flat spin in that configuration. Better yet, go get an ABS BPPP instructor and ask him or her to do one of those with you and see what their response is. Here is the link: www.bonanza.org/training/pilot-training/
Don't Barons have the tendency to get into unrecoverable flat spins if you stall with asymmetric power? I think Barons have a minimum intentional engine inoperative speed for this reason.
In the Embraer simulation, were the control movements duplicated from the flight data recorder? The reason I ask is: you state that the aircraft yawed excessively because "the pilot is not trying to achieve a 5 degree bank into the operating engine", yet, the controls show that the PIC WAS putting right aileron input into the yoke, apparently to no effect. So my question is, were the ailerons simply ineffective at that speed? Or should the PIC have given it MORE right aileron? The PIC was obviously moving the yoke/ailerons to the right in some sort of attempt to bank toward the operative engine. We all know that the more control surface deflection you make, the more drag you create. How does that factor into the equation of how much you should try to deflect the ailerons, and at what point are you just chasing the drag curve with no hope of achieving an equilibrium that allows continued flight?
I do appreciate your feedback and questions. The Australian TSB had the animation made for which they must have used FDR data. The pilot indeed used rudder and aileron, but not agressively and adequately enough. The aircraft continued to yaw and roll at the current airspeed, which are signs of the loss of control with the current, not large enough, control deflections. A pilot, after engine failure, should use rudder and aileron to maintain straight flight and bank 5° into the good engine for maintaining control and for minimum drag (smallest sideslip angle, lowest drag). When the airspeed is VMC(A), the rudder and/or aileron need to be maximum deflected; this is the definition of VMC(A). At VYSE or takeoff safety speed, still 3° of bank is required for minimum drag, for max. ROC. The drag of (individual) control surfaces is the least of the concern; the safe continuation of the flight requires maintaining control, for which maximum rudder and/or maximum aileron might be required. If the pilot of this aircraft would have used up to full rudder and max. aileron for attaining, and thereafter adequate deflections to maintain straight flight with 5° of bank towards the good engine, the aircraft would not have crashed, ME aircraft are designed and flight-tested to do so. Please refer to the VMCA page of my website www/avioconsult.com/Vmca.htm, and to papers #3 and #6 on the Downloads page for more on this subject. Have you seen my comments to the Australian Safety Report of this accident? Download this here: www.avioconsult.com/downloads/Review%20report%20accident%20EMB-120ER%202010-03-22%20AO2010019.pdf. Fly safely. Harry Horlings.
Wow. This was a great video and you made some really important points esp wrt Vmc vs Vmca... and why the copy and pasted version is crap (for tail design use only). Makes a lot of sense... Great job. I am not a twin pilot, but incorporating the logic of your argument makes sense to apply the 1.05+10knots with ANY plane. The immediate 5 deg bank INTO the good engine on failure, should be taught and practiced. Imo this is game changing for the safety of AV community. First Look Group below posted the Wichita crash link. Left rudder? Why would any sane pilot do that?
First of all thank you for your contribution to aviation safety with this excellent and well done educational video on VMC. I have a question. You showed a graph for the C130 (I believe) that compared VMC speeds in different bank angles and bank direction. I was shocked by the large percentage speed increase in VMC at the greatest bank angle when the airplane is banked INTO the dead engine. It’s perfectly clear to me that given an engine failure in twin the bank angel must be into the operating engine; raise the wing of the inoperative engine. This is my question; why does VMC increase (not stall speed, but VMC) when the airplane is banked into the failed engine?
In order to understand the answer to this question you have to understand the single engine aerodynamics behind what affects Vmc. Simply put when an engine fails, two things happen. A yaw and a roll into the dead engine. If you turn into the dead engine you’re allowing that airplane to turn you more into that dead engine. In most instances people try to maintain a specific speed when they simply do not have the performance. Raising the dead helps decrease Vmc speed because a portion of your Horizontal component of lift is actually aiding you in the rudder force necessary to maintain directional control. If you bank into the dead engine same principle applies except now instead of the HCL helping you maintain directional control. Now you need that much more rudder force to counteract that yaw. At some point when rudder reaches full travel you no longer have the rudder authority to maintain directional control hence why you lose directional control. The rudder effectiveness is determined by speed and the vertical stabilizer is an airfoil, the same way the wings can stall so can the vertical stabilizer.
Excellent! Thank you. Everything you said is correct. Some questions from me: In the first crash example, would it not have been very difficult for a pilot to recognize the sudden failure of the right engine unless the pilot was staring at the engine gauges? Certainly the pilot would have felt or observed the yaw to the right *after it began to occur* but in this example, wasn't that too late? However, if the pilot had rotated at 1.05 Vmca +10 knots as you say, he would have had more airspeed, and perhaps an extra two seconds to figure this out and attempt to stop the yaw. However on that aircraft, and in your example the pilot did not appear to have had sufficient time to process thought to *reduce* maximum thrust on the operative engine to prevent the roll, while at the same time mentally processing the other multi-engine emergency procedures - banking into the operative engine not more than 5 degrees, controlling the yaw, gear up, flaps up. Do you agree or am I incorrect? I fly a Seneca II and am applying your lesson IMMEDIATELY to my flying. Thank you for sharing your important analysis.
happysawfish, I fully agree to your excellent analysis. Indeed, recognition, processing and appropriate actions at too low a speed are nearly impossible; loss of control cannot be avoided. The safety margin is still very small when rotated with wings level at Vmca+10, but the airplane motions are not that vigorous, as the second accident shows. Pilots will have time to analyse why their rudder is not effective enough to counteract the yaw (provided they viewed this video). The Seneca Flight Manual I have requires closing both throttles if the airspeed is < 85 kIAS when an engine fails during takeoff - a pretty good safety margin. Thanks very much for your feedback, I really appreciate that. Please tell other pilots, and post this on pilot fora, because I can't anymore; I was kicked out because my work was regrettably seen by moderators as commercial, not preventive.
+AvioConsult I still say the co-pilot should have noticed it and aborted take off. At minimum shut both engines down and take your lumps! As the minimum airspeed before rotation is right on the gauges. As it's the co-pilots job to confirm minimum rotation speed has been achieved. If he says no, you either abort or wait till you do. But I'm smarter because of what you taught me...
Wow. I would never have guessed bank angle is so significant in loss of an engine. You can see pilots chasing the stalling wing in accident footage which increases Vmca. Can you discuss the effects on flight control if little or no rudder input is provided after an engine failure? Is the drag reduction favorable?
Hi, turning into the dead engine has negative consequences like increasing Vmca, but assuming you can maintain safe airspeed, can a better single engine climb rate be achieved by turning into the dead engine compared to turning into the operating engine due to less rudder deflection and therefore less drag from the rudder? Thank you.
Sorry for a late answer. Banking to either side results in a sideslip which increases the drag. Please refer to papers 3 and 6 on the Downloads page of my website avioconsult.com in which I explain and calculate the effects of bank angle and weight. Best practice is to climb straight ahead (5° bank into good) to a safe altitude, then reduce asymmetrcal thrust a bit, temporarily, which reduces both Vmca and rudder/drag, sacrifying some altitude. The higher the speed, the less rudder is required to counteract the asymmetrical thrust, the less drag and loss of performance remains.
Excellent. Having designed examination papers for many years, I'm well aware of the importance of unambiguous wording, which should be appropriate for the reader it is aimed at and avoid complication: e.g. 'critical engine' is superfluous in a flight manual - and adds complication. In an emergency, we do not want pilots wasting precious moments over irrelevancies. The wording of manuals is absolutely critical, yet all too often standardised phraseology is regurgitated over and over, such that it takes hold upon reader AND WRITER; student AND INSTRUCTOR; industry AND AUTHORITY - as if sacrosanct, with no further thought given!
Thanks Cosi. I am also very disappointed about the wording and phraseology that manual writers use in Flight Manuals. I recently was asked by a few ATR-72 pilots to review their manuals. These are even worse than I ever imagined. In about a week, I'll be finished with the limited review and post it on the downloads page of my website. You might be interested.
Absolutely perfect explanations and demonstraions!!! This information should be like a "bible" for twin engine pilots...I'm an electric/electronic engineer(doing my final practices to get the degree) but aviation is my passion. This is one of the best videos I ever watched. Engineers calculate EVERYTHING with high enough safe margins, but I certainly think that the TO speed is very near the Vmca, I believe 5% is a very low margin given the fact that when an engine fails so close to the ground and with a high AOA the speed will drop immediately, and probably for some airplanes this TO speed is almost the "wings leveled" Vmca. Why don't the flight manuals publish a higher TO speed, "just in case"? Why most of the pilots have to investigate on their own to get te safest speeds?? Shouldn't the wings leveled Vmca be published to have a better safety margin? I'm sure some instructors will add this 10kt safe margin but I believe in general there is also an excess of comfidence on the engines' performance and piloting skills that certainly leds to catastrophic accidents.
I agree with you, Diego. With such low safety tolerances, one begins to wonder whether flight manuals are designed to impress potential buyers (useful figures to bolster the sales person!), due to the psychological impression of 'better' performance!
Oh thanks god I was not piloting this plane otherwise I would had made a right turn (into dead engine) smother turning, but it would had been a mistake. Thanks for the explanation
vmc does not get it what the hell happened to v1 and v2. I have personely had engine failure and one happened right after take off in a Lockheed 12 v2 was 98 m.p.h and the arcraft had no problem and slowly gained speed through the return for a smooth landing at the airport I had just departed. another one happened in a B25 and v2 came at 145 m.p.h. same result no big deal. in those days we used m.p.h. later it all changed to knots.
While the analysis is interesting and on point, using the second example to illustrate the point is off. If the aircraft is certified with an auto feather and it was not put in simulated flight to represent these conditions, then likely no technique would allow it to maintain required speed on the V1 cut. The E120 pilot did infact attempt to raise the left wing a couple of times, but his lack of full rudder thwarted his efforts. Also the VMC definition is used because there is a need for pilots to understand the factors used to determine VMC. I know of no multi pilot that assume Vmc is a "safe" airspeed to use. It is drummed into every student that Vmc is that, the minimum speed, lower and you will lose control. Vyse is the airspeed target. So no 5 degrees of bank would have saved either of these flights. There is a risk involved with flight below Vmc as in the first example, and there is risk involved with improper configuration for V1 cuts and simulated single engine flight. The video is informative, but unlike the assertions, it is not at odds with what multi engine pilots are taught. Airspeed =Control=Life.
I am type rated in the EMB-120 and flew it as a FO and Captain for over 900 hours for a 121 carrier in the US. We had to do an engine failure, at V1, AND have auto feather failure as part of our training. We would have to feather the prop manually. If V2 is maintained along with correct rudder and bank inputs, the Brasilia will not VMC roll. The reason this plane did is a combination of what the video spoke of- Not maintaining V2, (the airspeed degraded down to as low as 103 knots very quickly after take off), not putting in and maintaining the correct bank into the operative engine along with correct rudder inputs, and the pilot flying increased the Torque from 94% to 108%, which increased VMCA as well. If you read the report by the ATSB, they conclude that factors in this accident were the pilot flying increasing torque, incorrect rudder and bank, engaging the yaw damper, and operating at an incorrect airspeed. Also, in this accident, there is a disclaimer from the ATSB in the full video which states :The yoke and rudder pedal movements could not be used directly because of a sensor problem, an analysis was done and the inputs in the animation are estimates only. The EMB-120 can and will maintain heading with an engine failure and auto feather failure if flown correctly, I had to do it for my type ride and at least once a year for my PIC check. As for the other accident, they rotated way to early, and you are correct in that 5 degrees of bank was not going to save them at that low of an airspeed that close to the ground. The point that is being made is that early rotation was the culprit in that accident.
Thanks for the response! First off, I want to thank you for this insightful video. I think from some of the other comments here, that some pilots may not grasp the importance of the zero sideslip low drag configuration. Or, those commentors are not pilots and just repeat things they have heard. I believe it is equally safe to turn in either direction with OEI, as long as you maintain a zero sideslip condition. Let's say we fly at Vyse with the left engine shut down in minimum drag configuration. For the sake of discussion let's consider 5 degree bank and 1/2 ball to good engine minimum drag. Let us also assume that the speed we are flying requires a 17 degrees bank for a standard rate turn. So a right standard rate turn would need a bank angle of 17+5 or 22 degrees with 1/2 ball to right. A left turn with the same parameters would be just as safe and yield the same turn performance, if flown at 17 minus 5 degrees, or 12 degrees left bank, ball still 1/2 deflection to good engine. Of course this assumes that stall speed increase for bank angle is considered. At what speed would turning flight be safe and how does that speed relate to Vmca or Vyse? Please let me know if my understanding of the situation is correct. Thanking you in advance for your answer!
@@timsaxer6442 When OEI, a sideforce generated by either the rudder, a sideslip or both is needed to counteract the asymmetrical thrust in order to prevent uncontrolled yawing and high sideslip/ drag. At Vmca, the rudder is usually max. and the sideslip is reduced to zero by a small bank angle (5°). At a higher speed, like Vyse, the rudder required is less than max. For minimum drag at Vyse though, you would still need a small 2° - 3° bank angle. If you increase the bank angle into the good engine for a turn, the sideslip to that side increases. The resulting side force due to this sideslip enhances the side force due to rudder causing a yaw into the good engine. If you don't decrease the rudder, the fin might also stall if the airspeed is not high enough. Banking into the inop. engine will cause the airplane to slide off to that side increasing the sideslip and drag. The resulting side force due to this sideslip decreases the rudder generated sideforce that was required to counteract the asymmetrical thrust. The airplane will yaw into the inop. engine. You'll need more rudder, but if the rudder is already max. at the given airspeed, the rudder cannot counteract the asymmetrical thrust anymore. You either need to accelerate, or decrease the asymetrical thrust (temporarily a bit) to regain directional (heading) control. If you don't, you'll lose control and collide with the terrain (laws of physics). During turns at asymmetrical thrust, you cannot maintain a zero sideslip condition. The ball does not show sideslip while the thrust is asymmetrical. Lockheed recommends to avoid turns into the inop. engine because of the increase of Vmca above the flight speed and the resulting loss of control. Only a few manufacturers publish safe speeds for turning with OEI. I've seen a Twin Otter Manual in which it is recommended to increase the speed to 30 kt above Vmca for safe turns with flaps 10 (which is also higher than Vyse). Don't believe what most people write on the subject; separate chaff from wheat. Ask the manufacturer of your airplane, make him aware of your concerns. A manufacturer is responsible for publishing the limitations for the safe operation of his airplane, including during engine-out operations, in the Flight Manual. Please also refer to the papers on my website. I realize this is not the quick answer that you were looking for, but I don't have the required data of most airplanes to recommend safe turns while OEI.
Excellent video. I noticed that the two accident case studies you included involve a part 23 and a part 25 airplane. I often find that pilots will apply part 25 jet procedures to part 23 piston aircraft. From a performance standpoint could you discuss how a takeoff planning in a part 23 aircraft schould differ from a part 25 jet since there is no V1 or V2 in these aircraft. I believe that an incorrect understand of single engine performance in part 23 aircraft leads to loss of control accidents as pilots attempt performance from an aircraft that isn't available. The hesitate to reduce AOA and in many cases increase it. This results is reduced rudder effectiveness. I believe that current training leads pilots to believe that if they immediately retract the gear and do everything right that their will climb. For a part 23 aircraft this is not true. Pre takeoff planning need to reflect this truth.
Thanks Omar. Although I wrote about performance deterioration in my papers (downloads page of www.avioconsult.com), I will review these papers shortly and see what can be improved. For now, the takeoff speed of part 23 should protect for the loss of control, but only if straight flight is being maintained while maintaining a small bank angle of 5 degrees to the same side as foot pressure, which will not only keep Vmca low, but also reduce the drag, and result in max. remaining climb performance. Indeed, this should be reviewed during pre takeoff planning (and might lead to a lower takeoff weight).
You wrote: "This video is not at odds with what multi engine pilots are taught". I agree but would change the subject: What multi-engine pilots are taught is no longer at odds with Airplane Design as taught by Dr. Jan Roskam (KU), with the FAA Flight Test Guides in Advisory Circulars and with the papers by a flight test expert on the downloads page of website www.avioconsult.com. The real problem, and the cause of many accidents, is what pilots do not learn anymore about Vmc(a), like the conditions under which Vmca is safe to fly. When the small bank angle is not being maintained, not only the drag increases (sideslip) but also Vmc (Dr. Jan Roskam, KU: "Vmca and Performance are tied together by the bank angle"). Therefore the technique to be used by pilots after engine failure is to maintain straight flight while banking 5 degrees away from the failed engine (The exact bank angle should be provided by the manufacturer with Vmc(a) data). The vertical tail of a multi-engine airplane is not designed, is not large enough, to be able to maintain control (and performance) for any other bank angle when the airspeed is close to or equal to Vmc(a) after failure of any engine, critical or non, while the opposite engine is set to provide max. thrust. During experimental flight testing to determine Vmca and evaluate the controllability during flight and during go-around, we apply this technique and we don't crash. Lack of adequate rudder increases the actual Vmca, i.e. the Vmca that the pilot experiences in-flight. The E120 pilot allowed the heading to walk away from the initial heading while he had ample rudder available, hence did not maintain both heading (straight flight) and a small bank angle. Vmc is a safe airspeed provided a pilot understands and applies the conditions that come with it. The Vmc published in flight manuals is the worst case Vmc that a pilot will ever experience in-flight. It is safe, but only if he or she maintains the heading and the small favorable bank angle. Otherwise Vmc will increase above the IAS and the dead engine will turn into a killing engine. These important conditions were and are regrettably not published in pilot manuals and course books anymore during the past 50 years. Exceptions: Lockheed C-130 manuals and old DC-8-63 manuals. Five degrees of bank would have saved the E120 flight for sure; it's undisputable physics: the balance of forces and moments. Neither the flight instructor, nor the pilot was obviously aware of the real value of Vmca, because there are probably no course books anymore that are right on this subject. Most, if not all pilot course books are not in agreement with Roskam and the Flight Test Guides issued by (an other department of) the FAA, that are also used at Test Pilot Schools. Even FAA-H-8083-3a/b Chapter 12, Transition to Multi-engine Airplanes, is definitely not right. Please refer to the downloads page of the mentoned website, download #8. I really wish you could show me a ME rating course book in which Vmc is correctly explained. By the way, Vyse is not safe either to turn either when one engine is inoperative and the other is at max. thrust.
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This video is the most important information I’ve ever seen for flying twins. As a multi-engine flight instructor and survey pilot, I think this video should be a must watch for every pilot of a twin.
RTC uses AvioConsult in their training curriculum for the Twin Engine recurrent training.
I appreciate your response Ibrahim, it means that the subject keeps you busy and you obviously want to prevent accidents.
Turning to either side, while an engine is inoperative, increases the sideslip angle and hence, the drag. The single engine climb performance at low speed is only maximal during straight flight and while also a small bank angle into the good engine of 5° is being maintained at Vmc (Vmca), or 3° at Vyse, or smaller when the airspeed is higher. This is a consequence, for pilots an operational maneuver limitation, of the FAA and EASA approved airplane tail design criteria (in FAR/CS 23.149 and 25.149). On most small twins you will not have a positive Rate of Climb at all when banking away from the favorable small bank angle.
Don't forget that the asymmetrical thrust does not decrease during a turn and needs to be counteracted whatever the turn direction and airspeed. Lots of variables here!
Please refer to a paper I wrote on these subjects, in which turns are also discussed and graphs are presented showing sideslip during banking, and where you also can find answers: www.avioconsult.com/downloads.htm#Investigators.
This will be a must watch video for my students. Brilliant stuff. A real service to the aviation industry. Thank you.
Thanks for your comment. It supports the conclusion that control after engine failure, and therewith the appreciation of the real value of Vmca, got less and less attention during the past 40 - 50 years. I've old DC-8-63 and current C-130 manuals, besides Test Pilot School manuals, that present the right stuff on the subject. Most FI's and authorities who I talked to, told me "never heard of it, cannot be right what you're saying" (they are younger than you and I). How do we get to teach all multi-engine pilots the real value of Vmca again, and the do's and don'ts that come with it? Pilots (and their pax) don't want to get killed, do they?
I am in the process of obtaining my MEI and appreciate the thorough explanation. I want to be safe and teach safety with understanding. My take away is 1) speed, 2) 3-5 degrees aileron, rudder ( for straight flight, then cage the engine. Thank you so much. I too will share this with my ME students.
Would you please upload some more content.
New into multis went through a lot of muli engine textbooks this was far the most insightful, brute and important information ive come across
Thanks for your reply, is well appreciated.
Spot-on Harry! I'm currently flying large, transport category jets, but am about to get back into light twin flying and instruction. I happened upon you outstanding video while studying. Very good food for thought and thank you so much for taking the time to make this presentation. Dank je.
Valuable source of knowledge on a critical topic when flying multiengine. Thanks for sharing Harry!
I regret very much that this accident happened; my sincere condolences to the families who lost loved ones.
The accident is very similar to the EMB-120 accident in the video. Loss of control, even when the airspeed was V2. This proves that V2 is not a safe takeoff safety speed.
This ATR72 accident should not have happened; proper limitations are in place (in flight and ops manuals) but are regrettably not understood anymore by airline pilots. I do not blame the pilots, but do blame the authorities in the USA (FAA and NTSB), in Australia (ATSB and CASA) and in the Netherlands to whom I wrote letters and e-mails many years ago telling that airline pilots operate their airplanes after engine failure in a way that is definitely neither in agreement with the limitations that are the consequence of the design/ sizing process of the vertical tail of multi-engine airplanes, nor with the way that the minimum control speeds are determined by experimental test pilots and flight test engineers, who are graduate of one of the few test pilot schools. These authorities do not understand this either. The oldest Flight Manual that was right on this subject I've seen is a DC-8-63 manual, 50 years ago. Thereafter the proper knowledge faded away (except at Test Pilot Schools).
All engine-out airspeed limitations (Vmca, V2min) are valid only while maintaining straight flight, that is while banking a few, up to 5 degrees, away from the inoperative engine. The manufacturer should specify the exact number of degrees, but the FAA and EASA do not require this.
I wish somebody could send me a pdf copy of a few pages out of the ATR72 AFM with Vmca and V2 definitions, engine emergency procedures and one engine inoperative performance data tables/graphs, to analyze and review and let the world know whether these are right for this airplane. No pilot wants to get killed due to inappropriate manuals, I'm sure. I can help and will publish the result on my website avioconsult.com. On the downloads and accident pages are many papers available.
Fly safely.
In-depth information. Thanks very much for this video
When banking into the good engine, the sideforce due to weight, that acts in the cg, increases to the good engine side. It is easier to see this while working in the body-axes system, the lateral axis of which runs from wing tip to wingtip throught the cg. Because of this increasing sideforce, the airplane starts sideslipping into the good engine until the opposite side force due to the sideslip is increased large enough to counteract the sideforce due to banking in the cg. A rudder sideforce to the dead engine side remains required to counteract the thrust yawing moment which adds to the banking sideforce. The fin and rudder can only generate this higher required opposite side force if the airspeed is higher (the force is proportional to V squared). The minimum speed for maintaining equilibrium of forces and moments when banking into the good engine is higher or, in other words, the actual Vmc is higher. If the airspeed is, or decreases below this higher required airspeed, the equilibrium of side forces and yawing moments cannot be maintained and the airplane continues to sideslip and, if the altitude is low, flies into terrain. If you need to learn more, please review thisTest Pilot School course: www.dtic.mil/dtic/tr/fulltext/u2/a319982.pdf.
Thank you Harry Horlings! Awesome analysis and discussions!
Excellent presentation. I will be passing this to all the pilots I know.
+W. Hawaii, thank you very much. Together we can make aviation safer, in 2016 and beyond.
Excellent video. Some new information for me. Thank you so much for posting this.
As a pilot and aeronautical engineer myself, I found this video very interesting. I have dealt with both the CS 25 and airplane flight manuals, these documents are essentially very different and it shouldn´t be the pilots job to interpret or understand the certification specifications. One note however on slide 34 (39:00), with Vto I assume you mean rotation speed Vr? My understanding of Vto is this is the lift-off speed, the speed at which the entire aircraft just lifts off the ground and it is of no operational significance.
Thank you. This is very helpful.
This is an eye opening presentation. I'm sure there was probably discussion about Vmca changing under different conditions when I started flying twins and bought my Baron 20 years ago but there were no charts quantifying it and the conditions that change it the way you have done here. I think the normal curriculum has been over simplified (dumbed down) to give new pilots easy to remember simple rules that marketing folks need to make the aircraft seem more versatile. This presentation has given me pretty specific things to think about in my SOP.
What are your thoughts on VG's lowering the Vmca? Would the improvement be proportional through the different scenarios that you describe? Thanks.
Thanks, great content!
Yes, now its evident: on takeoff with the usual required high AOA, if the nose starts an un commanded/ unexpected yaw say to left, the automatic reaction might be compensate with yoke/aeleron to the right with the wrong assumption that the plane is turning rather than yawing. But if left engine is failing that could be fatal as the lowered left aileron flap now increases the AOA on tht side aggravating the situation. The answer is immediately lower the nose to increase speed and reduce AOA and right rudder and select safe heading to track to prevent the uncommanded turn thats a actually due to yawing from reduced thrust on that side. When in doubt use rudder and reduce AOA until can clarify why the yaw/turn was occuring. Aileron needs to be used secondarily not primary. Also must demand traffic pattern with gentle turns to the good engine, his lecture makes it clear that even normal bank angles on the bad side can cause sudden loss of control as VMC can drastically increase with bank angle and the bad part is there would be no real-time warning by the systems as to the impending fatally reduced margin of error wrt speed management.
Saving for my MEI/Comm Multi in a few weeks. Love it
A great analysis and very thought provoking. Thanks for your time and efforts.
This video should be required viewing for pilots (up there with the American Airlines Advanced Aircraft Maneuvering Program series).
+Ben Kolbeck
Thanks Ben, please help by forwarding the link of this video to other pilots and instructors.
+AvioConsult I assign this video for all of my ME candidates thanks for the great video!
Tommy Sikes
Thanks, Tommy for the feedback. I really appreciate that. Together we can make aviation safer.
Thanks for posting this video. Very good presentation.
Terrific and scholarly presentation of a subject that should be much more widely taught and understood. Thank you.Jonathan Friedman ATP, CFI, MEI
Airplane Accidents after Engine Failure - Real Value of Vmc very important
Thank you very much for this. Brilliant, concise, and thoroughly helpful.
When I was getting my multi engine rating 37 years ago my instructor made me experience this loss of control at 5000 feet above ground and allowed the plane the completely roll over and note the speed when it began Beech Baron e55. In that experience I never forgot how useless the controls were. and I always took it upon myself to practice whenever got the chance.
That was just plain stupid and reckless by your instructor. A high asymmetrical Vmca roll in any twin that is allowed to fully develop into loss of control is about as dumb an intentional maneuver you can do. You are lucky you are not dead. Do a google search on that, especially in Barons, which have a propensity to flat spin in that configuration. Better yet, go get an ABS BPPP instructor and ask him or her to do one of those with you and see what their response is. Here is the link: www.bonanza.org/training/pilot-training/
Don't Barons have the tendency to get into unrecoverable flat spins if you stall with asymmetric power? I think Barons have a minimum intentional engine inoperative speed for this reason.
Nicely presented with calm attitude
Thanks a lot
You can always close the throttles and land straight ahead!
Wow! Great video! Thanks so much for the generous sharing of your knowledge!
In the Embraer simulation, were the control movements duplicated from the flight data recorder? The reason I ask is: you state that the aircraft yawed excessively because "the pilot is not trying to achieve a 5 degree bank into the operating engine", yet, the controls show that the PIC WAS putting right aileron input into the yoke, apparently to no effect. So my question is, were the ailerons simply ineffective at that speed? Or should the PIC have given it MORE right aileron? The PIC was obviously moving the yoke/ailerons to the right in some sort of attempt to bank toward the operative engine. We all know that the more control surface deflection you make, the more drag you create. How does that factor into the equation of how much you should try to deflect the ailerons, and at what point are you just chasing the drag curve with no hope of achieving an equilibrium that allows continued flight?
I do appreciate your feedback and questions.
The Australian TSB had the animation made for which they must have used FDR data.
The pilot indeed used rudder and aileron, but not agressively and adequately enough. The aircraft continued to yaw and roll at the current airspeed, which are signs of the loss of control with the current, not large enough, control deflections.
A pilot, after engine failure, should use rudder and aileron to maintain straight flight and bank 5° into the good engine for maintaining control and for minimum drag (smallest sideslip angle, lowest drag). When the airspeed is VMC(A), the rudder and/or aileron need to be maximum deflected; this is the definition of VMC(A). At VYSE or takeoff safety speed, still 3° of bank is required for minimum drag, for max. ROC.
The drag of (individual) control surfaces is the least of the concern; the safe continuation of the flight requires maintaining control, for which maximum rudder and/or maximum aileron might be required.
If the pilot of this aircraft would have used up to full rudder and max. aileron for attaining, and thereafter adequate deflections to maintain straight flight with 5° of bank towards the good engine, the aircraft would not have crashed, ME aircraft are designed and flight-tested to do so.
Please refer to the VMCA page of my website www/avioconsult.com/Vmca.htm, and to papers #3 and #6 on the Downloads page for more on this subject.
Have you seen my comments to the Australian Safety Report of this accident? Download this here: www.avioconsult.com/downloads/Review%20report%20accident%20EMB-120ER%202010-03-22%20AO2010019.pdf.
Fly safely.
Harry Horlings.
Wow. This was a great video and you made some really important points esp wrt Vmc vs Vmca... and why the copy and pasted version is crap (for tail design use only). Makes a lot of sense... Great job. I am not a twin pilot, but incorporating the logic of your argument makes sense to apply the 1.05+10knots with ANY plane. The immediate 5 deg bank INTO the good engine on failure, should be taught and practiced. Imo this is game changing for the safety of AV community. First Look Group below posted the Wichita crash link. Left rudder? Why would any sane pilot do that?
First of all thank you for your contribution to aviation safety with this excellent and well done educational video on VMC. I have a question. You showed a graph for the C130 (I believe) that compared VMC speeds in different bank angles and bank direction. I was shocked by the large percentage speed increase in VMC at the greatest bank angle when the airplane is banked INTO the dead engine. It’s perfectly clear to me that given an engine failure in twin the bank angel must be into the operating engine; raise the wing of the inoperative engine. This is my question; why does VMC increase (not stall speed, but VMC) when the airplane is banked into the failed engine?
In order to understand the answer to this question you have to understand the single engine aerodynamics behind what affects Vmc. Simply put when an engine fails, two things happen. A yaw and a roll into the dead engine. If you turn into the dead engine you’re allowing that airplane to turn you more into that dead engine. In most instances people try to maintain a specific speed when they simply do not have the performance. Raising the dead helps decrease Vmc speed because a portion of your Horizontal component of lift is actually aiding you in the rudder force necessary to maintain directional control. If you bank into the dead engine same principle applies except now instead of the HCL helping you maintain directional control. Now you need that much more rudder force to counteract that yaw. At some point when rudder reaches full travel you no longer have the rudder authority to maintain directional control hence why you lose directional control. The rudder effectiveness is determined by speed and the vertical stabilizer is an airfoil, the same way the wings can stall so can the vertical stabilizer.
How did you get Sean Connery to narrate your video?
Excellent presentation
Thank you
Excellent! Thank you. Everything you said is correct. Some questions from me: In the first crash example, would it not have been very difficult for a pilot to recognize the sudden failure of the right engine unless the pilot was staring at the engine gauges? Certainly the pilot would have felt or observed the yaw to the right *after it began to occur* but in this example, wasn't that too late? However, if the pilot had rotated at 1.05 Vmca +10 knots as you say, he would have had more airspeed, and perhaps an extra two seconds to figure this out and attempt to stop the yaw. However on that aircraft, and in your example the pilot did not appear to have had sufficient time to process thought to *reduce* maximum thrust on the operative engine to prevent the roll, while at the same time mentally processing the other multi-engine emergency procedures - banking into the operative engine not more than 5 degrees, controlling the yaw, gear up, flaps up. Do you agree or am I incorrect? I fly a Seneca II and am applying your lesson IMMEDIATELY to my flying. Thank you for sharing your important analysis.
happysawfish, I fully agree to your excellent analysis. Indeed, recognition, processing and appropriate actions at too low a speed are nearly impossible; loss of control cannot be avoided. The safety margin is still very small when rotated with wings level at Vmca+10, but the airplane motions are not that vigorous, as the second accident shows. Pilots will have time to analyse why their rudder is not effective enough to counteract the yaw (provided they viewed this video). The Seneca Flight Manual I have requires closing both throttles if the airspeed is < 85 kIAS when an engine fails during takeoff - a pretty good safety margin.
Thanks very much for your feedback, I really appreciate that. Please tell other pilots, and post this on pilot fora, because I can't anymore; I was kicked out because my work was regrettably seen by moderators as commercial, not preventive.
+AvioConsult I still say the co-pilot should have noticed it and aborted take off. At minimum shut both engines down and take your lumps! As the minimum airspeed before rotation is right on the gauges. As it's the co-pilots job to confirm minimum rotation speed has been achieved. If he says no, you either abort or wait till you do.
But I'm smarter because of what you taught me...
Great presentation, certainly a keeper for future reference. Just a SEL PP pursuing the Instrument rating.
Wow. I would never have guessed bank angle is so significant in loss of an engine. You can see pilots chasing the stalling wing in accident footage which increases Vmca.
Can you discuss the effects on flight control if little or no rudder input is provided after an engine failure? Is the drag reduction favorable?
i was in Darwin Australia when that Embrear crashed
Hi, turning into the dead engine has negative consequences like increasing Vmca, but assuming you can maintain safe airspeed, can a better single engine climb rate be achieved by turning into the dead engine compared to turning into the operating engine due to less rudder deflection and therefore less drag from the rudder? Thank you.
Sorry for a late answer. Banking to either side results in a sideslip which increases the drag. Please refer to papers 3 and 6 on the Downloads page of my website avioconsult.com in which I explain and calculate the effects of bank angle and weight. Best practice is to climb straight ahead (5° bank into good) to a safe altitude, then reduce asymmetrcal thrust a bit, temporarily, which reduces both Vmca and rudder/drag, sacrifying some altitude. The higher the speed, the less rudder is required to counteract the asymmetrical thrust, the less drag and loss of performance remains.
Thanks a lot ! Love you
Excellent presentation.
Thanks Art, appreciate your compliment.
Excellent.
Having designed examination papers for many years, I'm well aware of the importance of unambiguous wording, which should be appropriate for the reader it is aimed at and avoid complication: e.g. 'critical engine' is superfluous in a flight manual - and adds complication. In an emergency, we do not want pilots wasting precious moments over irrelevancies.
The wording of manuals is absolutely critical, yet all too often standardised phraseology is regurgitated over and over, such that it takes hold upon reader AND WRITER; student AND INSTRUCTOR; industry AND AUTHORITY - as if sacrosanct, with no further thought given!
Thanks Cosi. I am also very disappointed about the wording and phraseology that manual writers use in Flight Manuals. I recently was asked by a few ATR-72 pilots to review their manuals. These are even worse than I ever imagined. In about a week, I'll be finished with the limited review and post it on the downloads page of my website. You might be interested.
Absolutely perfect explanations and demonstraions!!! This information should be like a "bible" for twin engine pilots...I'm an electric/electronic engineer(doing my final practices to get the degree) but aviation is my passion. This is one of the best videos I ever watched. Engineers calculate EVERYTHING with high enough safe margins, but I certainly think that the TO speed is very near the Vmca, I believe 5% is a very low margin given the fact that when an engine fails so close to the ground and with a high AOA the speed will drop immediately, and probably for some airplanes this TO speed is almost the "wings leveled" Vmca. Why don't the flight manuals publish a higher TO speed, "just in case"? Why most of the pilots have to investigate on their own to get te safest speeds?? Shouldn't the wings leveled Vmca be published to have a better safety margin?
I'm sure some instructors will add this 10kt safe margin but I believe in general there is also an excess of comfidence on the engines' performance and piloting skills that certainly leds to catastrophic accidents.
I agree with you, Diego.
With such low safety tolerances, one begins to wonder whether flight manuals are designed to impress potential buyers (useful figures to bolster the sales person!), due to the psychological impression of 'better' performance!
The content is very good and accurate but this is a bit too drawn out to get to the point for me
Your thoughts on TransAsia Airways Flight GE235 crash
Oh thanks god I was not piloting this plane otherwise I would had made a right turn (into dead engine) smother turning, but it would had been a mistake. Thanks for the explanation
Dank je wel!
vmc does not get it what the hell happened to v1 and v2. I have personely had engine failure and one happened right after take off in a Lockheed 12 v2 was 98 m.p.h and the arcraft had no problem and slowly gained speed through the return for a smooth landing at the airport I had just departed. another one happened in a B25 and v2 came at 145 m.p.h. same result no big deal. in those days we used m.p.h. later it all changed to knots.
While the analysis is interesting and on point, using the second example to illustrate the point is off. If the aircraft is certified with an auto feather and it was not put in simulated flight to represent these conditions, then likely no technique would allow it to maintain required speed on the V1 cut. The E120 pilot did infact attempt to raise the left wing a couple of times, but his lack of full rudder thwarted his efforts.
Also the VMC definition is used because there is a need for pilots to understand the factors used to determine VMC. I know of no multi pilot that assume Vmc is a "safe" airspeed to use. It is drummed into every student that Vmc is that, the minimum speed, lower and you will lose control. Vyse is the airspeed target.
So no 5 degrees of bank would have saved either of these flights. There is a risk involved with flight below Vmc as in the first example, and there is risk involved with improper configuration for V1 cuts and simulated single engine flight.
The video is informative, but unlike the assertions, it is not at odds with what multi engine pilots are taught. Airspeed =Control=Life.
I am type rated in the EMB-120 and flew it as a FO and Captain for over 900 hours for a 121 carrier in the US. We had to do an engine failure, at V1, AND have auto feather failure as part of our training. We would have to feather the prop manually. If V2 is maintained along with correct rudder and bank inputs, the Brasilia will not VMC roll. The reason this plane did is a combination of what the video spoke of- Not maintaining V2, (the airspeed degraded down to as low as 103 knots very quickly after take off), not putting in and maintaining the correct bank into the operative engine along with correct rudder inputs, and the pilot flying increased the Torque from 94% to 108%, which increased VMCA as well. If you read the report by the ATSB, they conclude that factors in this accident were the pilot flying increasing torque, incorrect rudder and bank, engaging the yaw damper, and operating at an incorrect airspeed. Also, in this accident, there is a disclaimer from the ATSB in the full video which states :The yoke and rudder pedal movements could not be used directly because of a sensor problem, an analysis was done and the inputs in the animation are estimates only. The EMB-120 can and will maintain heading with an engine failure and auto feather failure if flown correctly, I had to do it for my type ride and at least once a year for my PIC check. As for the other accident, they rotated way to early, and you are correct in that 5 degrees of bank was not going to save them at that low of an airspeed that close to the ground. The point that is being made is that early rotation was the culprit in that accident.
@AvioConsult. Are you still responding to questions/comments regarding this video?
Sure, but may be not the same day.
Thanks for the response!
First off, I want to thank you for this insightful video.
I think from some of the other comments here, that some pilots may not grasp the importance of the zero sideslip low drag configuration. Or, those commentors are not pilots and just repeat things they have heard.
I believe it is equally safe to turn in either direction with OEI, as long as you maintain a zero sideslip condition.
Let's say we fly at Vyse with the left engine shut down in minimum drag configuration. For the sake of discussion let's consider 5 degree bank and 1/2 ball to good engine minimum drag. Let us also assume that the speed we are flying requires a 17 degrees bank for a standard rate turn.
So a right standard rate turn would need a bank angle of 17+5 or 22 degrees with 1/2 ball to right. A left turn with the same parameters would be just as safe and yield the same turn performance, if flown at 17 minus 5 degrees, or 12 degrees left bank, ball still 1/2 deflection to good engine. Of course this assumes that stall speed increase for bank angle is considered. At what speed would turning flight be safe and how does that speed relate to Vmca or Vyse?
Please let me know if my understanding of the situation is correct. Thanking you in advance for your answer!
@@timsaxer6442 When OEI, a sideforce generated by either the rudder, a sideslip or both is needed to counteract the asymmetrical thrust in order to prevent uncontrolled yawing and high sideslip/ drag. At Vmca, the rudder is usually max. and the sideslip is reduced to zero by a small bank angle (5°). At a higher speed, like Vyse, the rudder required is less than max. For minimum drag at Vyse though, you would still need a small 2° - 3° bank angle.
If you increase the bank angle into the good engine for a turn, the sideslip to that side increases. The resulting side force due to this sideslip enhances the side force due to rudder causing a yaw into the good engine. If you don't decrease the rudder, the fin might also stall if the airspeed is not high enough.
Banking into the inop. engine will cause the airplane to slide off to that side increasing the sideslip and drag. The resulting side force due to this sideslip decreases the rudder generated sideforce that was required to counteract the asymmetrical thrust. The airplane will yaw into the inop. engine. You'll need more rudder, but if the rudder is already max. at the given airspeed, the rudder cannot counteract the asymmetrical thrust anymore. You either need to accelerate, or decrease the asymetrical thrust (temporarily a bit) to regain directional (heading) control. If you don't, you'll lose control and collide with the terrain (laws of physics).
During turns at asymmetrical thrust, you cannot maintain a zero sideslip condition. The ball does not show sideslip while the thrust is asymmetrical. Lockheed recommends to avoid turns into the inop. engine because of the increase of Vmca above the flight speed and the resulting loss of control.
Only a few manufacturers publish safe speeds for turning with OEI. I've seen a Twin Otter Manual in which it is recommended to increase the speed to 30 kt above Vmca for safe turns with flaps 10 (which is also higher than Vyse).
Don't believe what most people write on the subject; separate chaff from wheat. Ask the manufacturer of your airplane, make him aware of your concerns. A manufacturer is responsible for publishing the limitations for the safe operation of his airplane, including during engine-out operations, in the Flight Manual. Please also refer to the papers on my website.
I realize this is not the quick answer that you were looking for, but I don't have the required data of most airplanes to recommend safe turns while OEI.
Excellent video. I noticed that the two accident case studies you included involve a part 23 and a part 25 airplane. I often find that pilots will apply part 25 jet procedures to part 23 piston aircraft. From a performance standpoint could you discuss how a takeoff planning in a part 23 aircraft schould differ from a part 25 jet since there is no V1 or V2 in these aircraft.
I believe that an incorrect understand of single engine performance in part 23 aircraft leads to loss of control accidents as pilots attempt performance from an aircraft that isn't available. The hesitate to reduce AOA and in many cases increase it. This results is reduced rudder effectiveness. I believe that current training leads pilots to believe that if they immediately retract the gear and do everything right that their will climb. For a part 23 aircraft this is not true. Pre takeoff planning need to reflect this truth.
Thanks Omar. Although I wrote about performance deterioration in my papers (downloads page of www.avioconsult.com), I will review these papers shortly and see what can be improved. For now, the takeoff speed of part 23 should protect for the loss of control, but only if straight flight is being maintained while maintaining a small bank angle of 5 degrees to the same side as foot pressure, which will not only keep Vmca low, but also reduce the drag, and result in max. remaining climb performance. Indeed, this should be reviewed during pre takeoff planning (and might lead to a lower takeoff weight).
You wrote: "This video is not at odds with what multi engine pilots are taught". I agree but would change the subject: What multi-engine pilots are taught is no longer at odds with Airplane Design as taught by Dr. Jan Roskam (KU), with the FAA Flight Test Guides in Advisory Circulars and with the papers by a flight test expert on the downloads page of website www.avioconsult.com. The real problem, and the cause of many accidents, is what pilots do not learn anymore about Vmc(a), like the conditions under which Vmca is safe to fly.
When the small bank angle is not being maintained, not only the drag increases (sideslip) but also Vmc (Dr. Jan Roskam, KU: "Vmca and Performance are tied together by the bank angle"). Therefore the technique to be used by pilots after engine failure is to maintain straight flight while banking 5 degrees away from the failed engine (The exact bank angle should be provided by the manufacturer with Vmc(a) data). The vertical tail of a multi-engine airplane is not designed, is not large enough, to be able to maintain control (and performance) for any other bank angle when the airspeed is close to or equal to Vmc(a) after failure of any engine, critical or non, while the opposite engine is set to provide max. thrust. During experimental flight testing to determine Vmca and evaluate the controllability during flight and during go-around, we apply this technique and we don't crash.
Lack of adequate rudder increases the actual Vmca, i.e. the Vmca that the pilot experiences in-flight. The E120 pilot allowed the heading to walk away from the initial heading while he had ample rudder available, hence did not maintain both heading (straight flight) and a small bank angle.
Vmc is a safe airspeed provided a pilot understands and applies the conditions that come with it. The Vmc published in flight manuals is the worst case Vmc that a pilot will ever experience in-flight. It is safe, but only if he or she maintains the heading and the small favorable bank angle. Otherwise Vmc will increase above the IAS and the dead engine will turn into a killing engine. These important conditions were and are regrettably not published in pilot manuals and course books anymore during the past 50 years. Exceptions: Lockheed C-130 manuals and old DC-8-63 manuals.
Five degrees of bank would have saved the E120 flight for sure; it's undisputable physics: the balance of forces and moments. Neither the flight instructor, nor the pilot was obviously aware of the real value of Vmca, because there are probably no course books anymore that are right on this subject. Most, if not all pilot course books are not in agreement with Roskam and the Flight Test Guides issued by (an other department of) the FAA, that are also used at Test Pilot Schools. Even FAA-H-8083-3a/b Chapter 12, Transition to Multi-engine Airplanes, is definitely not right. Please refer to the downloads page of the mentoned website, download #8.
I really wish you could show me a ME rating course book in which Vmc is correctly explained.
By the way, Vyse is not safe either to turn either when one engine is inoperative and the other is at max. thrust.
So the good engine won’t take you to the scene of the crime?
VMC 眼