The SECRET to a perfect descent
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- Опубликовано: 21 ноя 2024
- This is one of those skills I only learnt after getting my private pilots licence. How to descend from altitude and reach my chosen altitude at an exact point, for example, an airfield circuit. I share the magic formula I use to perfect my descents and approaches.
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To avoid any wind and distance in the equation, I use height and ETA. If I need to shed 10,000 feet, I can start 20 minutes out at 500 fpm. If the plane is turbocharged, I may use 250 fpm and 40 minutes based on my base formula just mentioned. That allows me to keep the temp up, and the airspeed just below red line in a calm air descent.
Good basic stuff, the kind you should learn whilst training for the PPL. But like the circular E6B I used to carry, I no longer do all this in my head (unless proving I can for a flight review) as the Garmin 430 we both have in our panels can show vertical speed required to arrive at destination. It updates continuously and lets you know if you’re ahead or behind on your rate of descent. Perfect descent profiles each time with ease.
Thanks for the instructional video! Clear, simple
And objective easily to understand! 100 score for you! Blessings and be safe!
I've always used 500fpm to be easy on the ears. When preflight planning, the winds aloft and ground speed are known (should be anyway), so top of descent can be calculated before the flight, significantly reducing workload. If arriving on the downwind side, I plan to be close to pattern altitude about 3 miles prior to the airport. That allows time to reduce speed and start pattern entry procedures - i.e. my route end is about 3 miles before the 45 degree entry leg.
"Overhead join"... haven't heard that term since my training days in New Zealand. In 3000+ hours over here in the States, where I now live and fly, I've NEVER heard that term. Brings back warm memories!
This is the one thing I'll never get used to in the UK, the dreaded and dangerous "overhead join"
Thank you for the great video !!! I personally use the formula all of the time. but the descent rate I use gs x 5 and adjust accordingly and have fun. Keep those videos coming !!!!
TOD in NM is altitude difference times 3 divided by 1000.
Calculating your VS to hold a 3° descent glide path is done by multiplying GS times 5. Very easy!
that’s exactly how it’s done and otherwise just use the Vnav function wich is available from handheld GPS to Boeing 787 navigation system.
During my training I often went to idle during descent and then cycled the power by increasing occasionally to warm up the engine. This was mostly in Cessna aircraft. I now have a Piper Archer and descent always with power set to about 2000.
Keep it simple, use time. Time is everything.
Need to lose 5000 at 500’/min, just double the ‘5’ = 10 minutes. Simples. Personally, I usually descend a minute or two earlier to make sure I’m level for TPA or the like.
- Won’t cool your engine too quickly
- minimal issue with winds
- and your pax ears will thank you too.
Absolutely this^^
If you know you need to descend for 10 mins for example, Just set power, even pulling the prop to a lower RPM to avoid ring flutter (a risk with very low MP and high RPM) that will give you 500'/min descent rate and the required GS which you can determine from your GPS GS that you had in the cruise when you commenced descent and you should then always be descending with power to avoid cooling issues or rapid uncomfortable descent rates (even a min or so earlier so as to arrive at the over fly height just prior to the circuit)
Achieving two different results I guess. He's achieving a 3 degree glide slope throughout the entire descent. His technique is great for those doing a straight in approach for example into a runway, not necessarily just joining the TPA/Circuit height. Worth noting UK don't use the terminology TPA that's a US only thing.
Came here to say exactly this. I also cheat and use Foreflight to quickly gauge the TOD point given the needed time. The ruler tool shows distance and time between 2 points.
@@jimjernigan3670that’s not cheating 😂 it’s just using your brain and tools 👍🏼
@@glennwatson P
TPA. I’m from the UK, Tomato ‘tomata,’ same same. Just whether you use height or Altitude. Altitude would save far more folk from straying in airspace, particularly places such as Blackbushe and White Waltham…
Great video. I'm just a flight simmer but I am glad to say that I do everything correctly besides the power to set which I will pay attention to. Thank you
Great presentation. Thanks
This is great! We've been using this formula in the airlines for decades. I didn't know anyone in GA who ever used it; most of those guys seemed to prefer a more complicated method for descent calculations which my mind quickly loses interest in... I used this method one late, late night after being given an unrestricted 'P.D.' descent into KIAH from FL380 in an Airbus 321. I manually pulled the thrust levers to idle at around 117 NM from the airport and left them there until we reached 500' AGL. It worked like a charm; and it was super quiet for the passengers until we had to spool up again for the last 500'.
Bingo. Newer airplanes with VNAV essentially remove the need to know. But they also lead to complacent and lazy pilots who won't recognize when the VNAV is improperly programmed, or has a bad waypoint, or, or, or. I've seen VNAV screw up more times than I can count. 3:1 will never fail, unless you have an outrageous tailwind. I am grateful that I learned this technique when flying a Mooney 231 way back in the 80s, turboprops in the 90's and then jets. My first was the B727. Two HSI's were all the Gee-Whiz you got. Two VORs and only one with DME HOLD. 6-pack steam gauges. You did your 3:1, then had to figure out your groundspeed (because there was no GS readout) and then make the wind adjustment to plan your descent. East bound in the wintertime you better darn well have your descent profile figured out way before the TOD. The beauty of 3:1 is that you just recalculate it every 1000 feet on the way down to determine if your coming down too steeply, not steep enough, or just right. The sooner you find out that you're too high the more time you have to fix it. Retired now and flying BizJets. I find that a LOT of the FNGs have no idea how to "properly" descend from cruise for landing when they're not being led by the hand by ATC, the VNAV or the other pilot.
Wow, So You Glided For 117 NM? I Wonder What The Record Is For An Airbus A321? Thank You. (Like #14)
@@megadavis5377 At a constant Mach no / IAS ?
@@thewatcher5271 , I can’t accurately say “we glided” for 117NM, but I can say we were at idle thrust for about 114 NM. We used a descent Mach number of .78 until the transition point then maintained approximately 300kts IAS until 10,000’. At ten we slowed to 250 kts before continuing the descent. Then we gradually slowed so we could begin to “dirty the airplane” for landing. Right at about 1000’ AGL we deployed the final “flaps 3” setting and reset the thrust levers to ‘Climb.’ It all worked out beautifully. I had practiced the maneuver on my home computer several times prior to actually stumbling upon the opportunity to do it for real.
@@lbowsk The airlines never taught descent management. It was always Dive and Drive. TWA 514 on Dec. 1, 1974 is a good example of how it kills not to know. They descended to 1800’ and were still 25 NM from IAD. If they had just been taught to use simple math and used it the would have been around 7500’ and above their impact point at 1680’. I flew the newer airplanes for my last 20 years and still used the simple math to confirm the FMS. I have seen the automation display major errors sometimes explained by an incorrect entry, but sometime unexplained.
I recommend selecting your desired descent rate in fpm and your descent ground speed first and then calculating the TOD accordingly. A comfortable rate of descent is 500 fpm and if your groundspeed is 120 kts, then you need 4nm per 1000 ft of descent. Assuming you always prefer a descent rate of 500 fpm, then the distance in nm needed per 1000 ft of descent is simply groundspeed divided by 30. Your formula is just the result for a descent rate of 500 fpm and a ground speed of 90 kts.
Nice way to shorten it up, divide gs by 30. Thanks
less math a person does in flight, the better.
A fixed descent rate of 500 fpm works great for VFR, however for IFR you are expected to fly the same flight path irrespective of your ground speed. Hence the formula he is using is an approximation of a constant 3° descent. (Note that the factor 3 working for a 3° descent is just a coincidence on the definition of NM and feet)
I do love this channel!
Next time you're in Earls Colne, Jon, take a walk down to Markshall estate, where there's a decent coffee shop. The walk will take you through woodland on a paved track around the outside of the Markshall arboretum deer fence.
If you're planning on visiting at a weekend and want to meet one of your fans, let me know and I'll come over! 😀
Thanks for another interesting vid and it’s always interesting to see the comments. Keeping the engine temperature up in the descent is only going to delay the shock cooling until later as arriving in the overhead at 2000 ft means all the cooling is going to take place in the next two minutes or so, whereas small step decreases in rpm from say, 10 miles out would make the cooling more gradual. Cheers
ForeFlight has a great tool called Descent to Destination. At all times throughout the flight it tells you how many feet per minute you would need to descent at if you started the descent right now. So what I do is I just wait until the number reaches 500 and then I initiate a 500fpm descent. Good to hear the math behind it though. Thank You!
Wait, what ?! How ?! I have never seen this in FF !
It’s in the gadgets at the bottom, go to settings and select descent to destination as one of your gadgets. It’s the most useful one of all.
@@OMA254 ah ! Found it ! I will try that out next time (but will need to replace an element I like to use...)
I use this all the time. and on final I periodically hold up my first three fingers held sideways. That's 3 degrees for me. If I'm on the glideslope they will just cover from the horizon to the touchdown aim point. It will make it very obvious if you are high or low. And remember 3.0 degrees is 90kts GS at 500 fpm. Ratio as appropriate for your GS
Pilot License (Licence) in the UK, Pilot Certificate in the U.S.
License: permission to do something. Certificate: a document confirming that someone has reached a certain level of achievement or competence.
Anyway, good video and thanks for the information.
This was figured out 50+ years ago by your countryman D.P. Davies the Chief Test Pilot for the ARB in his three editions of HANDLING THE BIG JETS 3xDistance NM is the altitude your looking, for one mile or 100 miles, 300 feet for each mile. Vertical Speed required is 5 x Ground Speed which results in the same answer as your formula with the additional step. The 3x Altitude is close but Davies 3 x Distance is closer to the desired 3 degree profile which is the target for a stable approach in transport category aircraft. A worthwhile discussion.
that’s exactly how it’s done and otherwise just use the Vnav function wich is available from every handheld GPS to 787 navigation system.
@@xyzaero Yep, that is exactly how TWA514 did it on December 1, 1974. Had they been taught simple math like much of the aviation world rather than hitting a small mountain and killing everyone they would have been at around 7,500’ passing their impact point. I had to take a job in Africa to be taught something that was never mentioned at any FAA regulated airline.
@@georgeconway4360 Yea I also did some 1500 hours of bush flying, skydive and aerial mapping as well as CFI operations before stepping up to jets. It’s great to have solid basics.
I use the following 'Rule of Thumb'...((Current altitude - Target altitude)/Rate of Descent) x Ground Speed in miles per minute and it works fine for me
thats a really complicated way of working it out! I use altitude to lose = 5000ft. if Im by myself, i descend at 500ft / min = 10 min. 10 mins at my GS 150 knots = 2.5miles / min = 25 miles. if i want to descend slower (if I'm flying with family), i may descend at 300ft / min = 16ish mins @ 2.5miles / min = 41 miles out. check descent and recalculate on the way down every 10 miles
Altitude to lose divided by rate of decent gives you time. Then just start decent when the ETA on the GPS is getting close to that time. Even easier is monitoring the decent rate required that is provided by the GPS. Then descend when the rate matches the rate you want. You will actually need to stop the decent before or descend slower since the GPS rate is to be at field elevation when you reach the airport. For a PA28 this is plenty of planning, probably not for a 747 though. GPS’s like the G3X let you tone in decent and show you on the map where you will reach your desired alt.
Besides sparing the engine, it's also more satisfying to do a high ground-speed cruise descent.
4:32 Much easier to divide ground speed by 2 then add a 0.
Eg
120kts ÷2 = 60
Add 0
= 600 fpm
Yep, that’s how I do it…..seems easier 🤷🏼♂️
Multiply by 5 is better. No adding, nothing else just that and done.
Why would you vary your descent rate? Stabilized descents, comfort, IFR procedures all focus on consistency and stability. Make 500 or so feet the norm, and find out how much *time* you need. 5,000’ to lose / 500fpm is ten minutes. Done,
@@tangocharlie9291 your descent rate is based on GS. If you do 500 feet descend rate and your GS is 70 then you would be below your glideslope. If your GS 60 and your descend rate is 500 fpm then you would als be below your glideslope. So GS times 5 gives your your approximate descend rate. Then of course adjust.
@@piloto2412 You are right, but only in this example where the glideslope is fixed. The TOD always will be 15nm if you need to lose 5000ft, therefore the glideslope is always the same. In order to comply with that glideslope you'll have to adjust the rate of descent based on GS, like you said. But you can do it the other way around, with a fixed rate of descent you'll have to change the TOD and with that, glideslope changes. This is important because sometimes you could have a mountain in the path!
DUDE YES…oddly, I actually picked this up from my flight simulator days. I noticed that at 6nm out, I’d be at 2000’ AGL, 3nm at 1000’ AGL, etc. when flying an ILS. This translates beautifully into VFR flying. The only caveat is that you have to plan for where you’re descending to because it’s usually not the runway itself. Is this pattern altitude? Are you overflying the field 500 above pattern altitude? Are you coming in on a big, wide base that’s gonna add some track mileage? Pattern altitude is definitely a good start in most cases…
I was taught:
Altitude to lose x 3 equals miles out to start down which ya showed.
Descent rate is ground speed / 2 and add a zero (GS 150 / 2 = 75, add a 0 and VSI is 750)
Same results just a different method obtaining.
So many old tricks and tips that new pilots don’t learn due to iPads, in-dash computers and magenta
This series is going to be immense! Great content, as always my friend!
You legend mate. ❤
Thanks Lew. I'd better come up with my next one then!!
@@TheFlyingReporter Please, please, please could you go through every stage of a perfect encadrement (PTU): the bits where you get the perfect alignment with the runway and wing (you could even explain how you can calibrate that with any aeroplane), and then those angles to land perfectly on the numbers.
This seems to be something that I only ever get to do on my check flights, as my aeroclub doesn't allow us to practice without an instructor.
Thanks for a great video! I will have to try this.
This is a great video John, after doing Atpls I've only just come to lean about TOD/TOC shocked it's not taught in ppl flying but then maybe it doesn't matter as ppl holders happy to tootle around 3k ft and below.
Yes you absolutely right. PPL allows you to learn flying.
I like the VNAV feature of GNS430/530 and G1000, as well as Bendix/King KLN74.
The real problem lies elsewhere, though - flying VFR on top, the destination weather changes from SCT to BKN, you just lost your option for continous descent approach. Yes, even a VFR pilot prefers to maintain max speed until short final, traffic permitting, of course.
Shock cooling is also a myth in Canada
If you’re getting radar vectored in controlled airspace, ask the controller how many track miles to run. Then apply the formula given to know if you’re on profile or too high or too low and adjust your rate of descent accordingly.
As a few others have said I plan for 500ft/min VFR descents. My ears are slow to equalize and it's more comfortable for any passengers too. I know that my plane's 500ft/min descent airspeed is about 120kts. So I take the altitude (in 1000s) I need to lose x 2 to give me descent time. Then double that to get distance from field to start the descent (2nm per minute traveled at 120kts).
Now this wont give the standard 3degree descent angle but If I'll have fewer ear/sinus issues after that flight.
I started learning in the ATC at age 16 in a Slingslby T21B glider. Start on gliders and you perfect landing, a go-round is not an option. Later if the engine goes on strike you can cope.
Great idea for a series and I did laugh at the early on-screen inclusion of your formula, you’ve been YouTubing long enough to have the measure of many of the commenters :)
As a fresh PPL and soon to be IRR student I would love to see some “secrets” about weather planning longer trips.
3xNM per 1000 works on most piston singles. Add or subtract a few miles depending on winds. In slick airplanes like the Comanche that have low flap and gear speeds I sometimes use 4 or 5x NM per thousand especially if I want to carry extra power on descent to reduce the chance of carb ice
this seems more qulity thn usual keep it up sir
On another topic: Have you tried holding the yoke between thumb and forefinger instead of tightly in your fist? You’ll get a better feel for whether the elevator is in trim. ;-)
I just target 500fpm and therefore the thousands of feet to lose × 2 gives me the minutes i'll spend descending. That again ×2 (ground speed estimate is usually around 120kts for me which is 2 miles a minute) = distance at TOD.
ground speed variations are then just added or sunstracted as percentages (e.g. 5kts faster = approx 5% more distance (rounded)).
works pretty fine
Shock cooling is not really a thing unless you are carrying parachute jumpers or towing gliders. Getting the engine too cold is however a concern because the clearances between piston and cylinder can get a little tight, and the oil can get too cold. If you are able to keep 20" of MP in the descent, you will be OK. Your cylinder temperatures will remain above 260°F and your oil temperatures will remain above 100°F (the minimum for take-off).
its not a thing until you need to pay for new cylinders 😅
@@jasonzhang8577 Do you own, or have you owned an airplane? Have you watched detailed engine data in flight, or have you had the opportunity to analyse such data after a flight? If you have, you know shock cooling is not a thing.
I have owned and flown a turbocharged 310 HP engine for 700 hours on which I went from 30" cruise MAP to 20" and have never observed shock cooling. Mike Busch has documented that shutting off (inadvertently due to an empty tank) an engine at cruise does not "shock cool" it.
Unfortunately some myths are hard to get rid of...
@@axel-stephanesmrgrav7036 yes I own a PA28 out right and I had a cracked cylinder after doing idle descent🙃 stranded in Leeds East for new kit that costed me a lot. Never ever done descent lower than 1800rmp since.
@@jasonzhang8577 That's however not shock cooling unless you went from a full power climb at VX or VY to an idle descent at -1000 fpm. A loose definition of shock cooling is when the CHT decreases by 50°F per minute or more. On top of that you would need to have some very hot cylinders to begin with.
Whatever your mechanic said the cause was, I cannot see how a cylinder would crack due to an idle descent. Problems with segmentation and scored cylinders would be a more likely outcome, not to talk about problems with the oil galeries if you advance the throttle too quickly after such a descent, since a low oil temperature would make the oil very viscous and could result in excessive oil pressure.
Those cracks often appear around the spark plug hole, or injector, and are more likely due to excessive application of tightening by some mechanic. You would be surprised how many of them are not bothered with whipping out a torque wrench to perform such mundane tasks.
It is also a lot more likely that crack are due to excessive internal cylinder pressures in combination with excessive cylinder temperatures. But you would not know unless you have a CHT probe on all cylinders, and an engine monitor.
Altitude to lose divided by desired rate equal distance. Example: To lose 4000 ft at 500 ft/min would be 8 minutes. Ground speed varies due to to winds never being accurate. If you have a GPS, it will show found speed. So let’s say 100 kts ground speed, you are traveling 1.6 miles per minute, (100/60). 8 mins time 1.6 equals 12.8, start a decent profile around 13 miles out.
God job
If you descent at 500 fpm you can use ETA instead of distance to easily make the required mental calculations. Take delta altitude (in 1000 ft increments) and multiply by two to get the number of minutes you'll need for the descent.
I hope u didnt forget to deicing before going throught that cloud !
I usually use sine rule when descending down straight to the runway in a sim. I haven't had it applied irl though
A 3 times profile can be too steep if your groundspeed is high... ie in a twin doing 180kts, your rate of descent would be 1000fpm. Or if you have a strong tailwind. I like to vary it, but I find starting with a 5-6 times profile achieves roughly 500fpm when doing 180kts. Profile descents are the way to go, especially if you plan to move into IFR flying. You always know where you are vertically. Easier on your and your passengers ears too.
Excellent, merci !
The myth of shock cooling continues....
is it a myth?
@@agauerm one of those things carried over from the old old days. I've read more modern engine focused articles talking about how it's all BS
Altitude divided by 500ft/m gives you time to ETA. You can do it by any descent rate you like (altitude divided by 700ft/m for example). If you don't have a GPS, then your watch (time to destination) is the most accurate guide.
If I'm flying a Baron at 180kt and I use the video formula, I get a descent rate of 1000ft/m. I would never use that as a standard rate of descent - passengers don't want their ears popping at 1000ft/m!
Use time, not distance. They are the same thing if you know your ground speed - which you should.
Depending on what “final” altitude you want to arrive at, a basic rule is your altitude times 5. Ex: Your altitude- 7000ft, 7 x 5=35. Start descending 35 miles back at 500ft/minute. This is a general rule which works fairly well, adjustments can be made based upon upper winds.
Another great reason to get an instrument rating.
I plan to descend at 500ft per minute as others have said to be easy on the ears. If the plane is doing 120kts that equals 2nm per minute. To descend 5000ft at 500ft per minute takes 10 minutes or 20nm from destination.
I’m a “time” kind of guy and I like to descend at 500 fpm.
Thousands of feet in descent x 2 two + one.
E.g. 7500 cruise altitude minus 1,500 pattern altitude = 6 (thousand) x 2 is 12 minutes.
Add a minute for safety. Start descending at 13 minutes out.
I asked continental ‘s engineers. They said shock cooling is not going to happen. The rate of cooling for that to happen is much quicker than when even doing a steep spiral at idle.
Under what circumstances? Cylinder cool shock cracking happens when shock cooling the engine descending at a high rate or high airspeed at idle power and then abruptly adding full power such as you would during a go around for example. I've seen the engines of a Baron that did just that and he cracked 5 cylinders. It's not a wives tale, it is a real thing that happens.
@@ShadowCompanyPMC Shock cooling is a myth.
"I've seen the engines of a Baron that did just that and he cracked 5 cylinders."
Anecdotal nonsense.
@@smark1180 you’re an idiot lol
@@smark1180Wrong. Try flying Agricultural ops for a while and you’ll find out all about cylinder cracking due to rapid changes in cylinder temperature changes.
@@shanelodge391 Don't tell me what to try, reply with evidence. Regardless, even if your claim is true, it's a false equivalency. Shock cooling as used here is in the context of normal GA operations, not crop dusting.
extremely lazy but the vnav calc function in the garmin GTN series is excellent for this... any plans for a panel overhaul Jon?
Calculating in your head is not lazy, it keeps your brain fresh. VNAV is great, but what do you do if it fails?
@@Darkoryou you misinterpreted my post - Jon's calcs are great and should indeed be fundamentally understood and practiced by all GA pilots. I meant that using the vnav calc on a navigator is lazy (but an excellent way of managing a descent)
Yes, I love the magenta curve on the G3X / GTN650 with altitude select.
I descend at cruise power, periodically pulling the throttle back and pushing the mixture forward to maintain my cruise settings. When to start is easy--500 feet per minute is 2 minutes per thousand feet, so I just count thousands of feet to lose, double that number and add one or two, start down that many minutes away. Simple, we can all count with our fingers and hopefully every pilot can multiply by two . . . . Higher speed I descent makes up for that slow climb to altitude.
The simple 500 fpm descent never changes, and rarely causes problems for any passengers who don't have head colds or sinus issues. Two minutes per thousand feet, plus a minute or two to level off and slow down. What could be easier?
And shock cooling has been disproven so many times by so many people, including the major engine manufacturers. It's disappointing to hear how many people keep reciting it like a mantra, but if shock cooling was a problem, why do jump planes not have engine problems, and why does flying in rain not cause shock cooling?
3 is only used with slower aircraft. The number varies with speed.
Like it!
Interesting, i use this formula. Sometimes i'm even lazier. With a EFB, I enable Track Vector in Minutes. I know the aircraft comfortable descent rate is between 500-800 ft per minute. therefore if I need to descend by 5000ft, i know i need to descend 10 minutes out at 500ft per minute. Again Adjust accordingly. No calculations needed
I usually take my foreflight and see how many minutes out I am. I usually do 250-500fpm. Every 2-3 min is a 1,000 basically. So if pattern is 1500 and I’m at 10500 is 9000 ft. So 18-27 min out.
After 30 years of flying I no longer give up any altitude before I have to. I am not an airliner and don't need to plan descents many mile from the airport. Unlike and airliner, I only have one engine. I only begin descents when I have the altitude or airspeed to reach the field should my engine fail. I understand certain aircraft are very slippery and long descents may be mandatory, however, many of these also have speed brakes to help in this scenario. I just don't agree with these airliner descents for general aviation aircraft. Of course to each his own, however.
sometimes you ight not be able to do that since you ar being cleared in for an airfield which might be located near a major airport. In this case they might send you down pretty early.
I always ensure I am at least high enough to make a suitable landing spot. I did have a Seattle center controller ask why I wanted 10,500 to fly from Bellingham to Olympia. I said that it not only puts me above the TCA, (I'm that old) but have you seen what's down there? 🙏🤣
I never pull the power to descend to the field .low power and put the nose down,. Seems to work for most pilots
How about: required decent in feet/(60/groundspeed x miles from waypoint)…
What does the POH recommend ,did'nt hear any mention of refereing to.
What kind of plane are you flying?
A PA28R-201T - Piper Turbo Arrow 3
Thanks for a good informational video. I am just angry at your school. All this should have been taught before your first cross-country flight. I certainly was before my flight
Where I live you can get your PPL without completing any cross country flights. It just means you are restricted to within 25nm of the airport until you complete the requirements.
Due to airspace around London, we never climbed above 3500ft, so planning descents was never an issue.
Sometimes, if I'm too high, I side slip the aircraft with no flaps. This is good fun so long you tell your passengers
I never understood these rules based on distances and ground speed. If I know my ground speed, it means I have some kind of electronic navigator, like Skydemon, an EFIS, or a GPS. All those devices give me my distance in minutes from my target. If I know my distance in minutes, then it's pretty obvious to know WHEN, rather than WHERE, I want to start descending, based on my desired rate of descent. No need to go back to distances if I have times. Or at least this is what I see...
Yes, I think that I am with you and there may be too much over thinking here: I always use ETE, I am usually down to within 3000 feet of where I want to be ten minutes before vertical of aerodrome: 3000/10=300ft/min 🤷♂
Easier formula is plan 500 Fpm and then figure number of minutes you will need to get from cruise to pattern altitude.
I must have not posted my original comment, But I use a shallower decent profile of 300-400 fpm. I fly a V35B usually at 11,500' out west at 60% power 20X2400, 12.5 gph that gets me an IAS of 148 kts or about 176 kts tas. To make pattern altitude I need to be at 4500 at the 45 for downwind. So 7000' at 333 fpm 21 min or so or about 65 miles. I initially accelerate to ttop of the green an IAS of 167 kts maybe to 180 kts if smooth air and trim slightly nose down to hold 333 fpn and at MP comes up I retard the throttle every 2 minutes or so an inch or so. Engine temps might go down by 20-30f total over the 21 minute descent but that's perfect, but I arrive at the 45 degree at 4500 feet at about an IAS of 125, perfect for half flaps and gear. In my former B58TC when I'm cruising at 15.500, I may start my descent 30 minutes out same procedure. Now I made up of lot of my climb time at IAS 120 kts (140kts in the 58TC). One in my T210 I made a 250 mile, 60 min descent from FL 280. Temps stayed almost constant. I like to see 300-400 fpm with power on, with IAS top of the green or if good air maybe 10-15 kt into the yellow. My engines go to TBO or longer with no cylinders inbetween. If in the flight levels I always ask for a discretionary descent. But I fly mostlly west coast, rarely in the eastern corridor where traffic gets real dense. I was taught to fly that way by some good instructors who flew commercially who had a motto that was "Never let your passengers know they ever left the ground."
The flying Reporter ideas have real merit, but I am even a bit less extreme.
0:41
Isnt shock cooling like a myth?
Va is safe manoeuvring airspeed? So surely a tailwind isn’t going to make a difference? The aircraft doesn’t know it has a tailwind…
The descent technique you've discussed is great for straight in approaches since it keeps you on a constant 3 degree glide slope.
Another technique for calculating the descent rate, GS / 2 (add a 0 to the end of the result). You don't need the * 10 step. Eg ground speed of 100 knots, 100 / 2 = 50, add a 0 to the end 500fpm. 80 / 2 = 40, add a 0 to the end 400 fpm
For joining circuit height a simpler technique (others have mentioned) you want to go from 7200 to 2200, 500fpm descent rate, that's 5000 / 500, so that's 10 minutes out, add a minute as a buffer. You should be keeping track of your ground speed using your navigation log anyway or also modern aircraft have it on the GPS.
Or you could just multiply by 5.
@@dangeorge809 Harder maths in the air. Lot less mental arthimetic doing it / 2
eg you're doing 140 knots * 5, err how many 5's is that, err
140 / 2 = 70, add a 0, 700
@@glennwatson what about speed of 135 or 145 kts? I find it more quicker multiplying by 5 rather than dividing by 2 and adding zero here. The best method for any speed is multiply by 10 then divide by 2. Thats what i do.
@@robinchhetri7266 I like that way too
....meaning, start decscent at 15 miles out...how to gauge that 15 miles?
Your navigation tool can help you
Easier take , first 2 numerals of GS . Halve it . 180 kts , 18 /2 = 9 . 900 fpm on a 3 degree . Or 5 x gS
Ok, so I know you said multiply by 10 and then half but that makes my brain freeze. Anyway halving first then times by 10 is easier and gets the same answer. Just in case anyone else's brain works like mine.
Whatever works for you - you can also multiply by five - but I find 130 x 5 a difficult one personally for example!
Multiply by ten is easy. Just add a zero to your number - any number!
never been shown this. More for airline planning
Maybe do your passengers a favour and not descend faster thstn 500 fpm. It’s the most comfortable rate to adjust to.
Then 500 fpm=2 min per 1000 then time to destination tells you when to descend. ie 5000 feet to descend start at 10 min out. Much easier
Take altitude and multiply by 3. That’s how many miles out to start your decent.
I would never put the gear or flaps down to make a descent. That’s poor planning on the pilots part.
I LIKE SO MUCH BRAZIL PILOT
Unfortunately, I was expected to know & experience dang near everything there is to know about aviation prior to earning my PPL (💀💀💀), and they still didn't really want to give it to me 143 hours later lol I WISH I couldve learned as I went through the rest of training.
How do u know your groundspeed
Why use distance? If you know time to station just start descent, so 7k to 2k is 5k. So 5000 divided 500fpm is 10 minutes before airfield.
Start at 12 minutes if you want to be level before reaching to slow down high speed aircraft.
Didn’t you pull the throttle back an inch or two and drop the nose? Wasn’t that the thing you were trying to avoid doing?
No. Dropping an inch or two is not the problem - Dropping 15 inches or worse, power to idle would be very bad. Essentially, descend on cruise power with this engine.
geez..by the time I do all the math I would have overshot the field...possibly needed for instrument rated pilots.
Take desired feet/500= descent in time at 500fpm😊
Why multiply by 10 and divide by 2? Just multiply by 5.
I'm bad at maths - divisible by 10 and half it is easier for me.
@@TheFlyingReporter I was going to make that point, it's easier to work out quickly
Because it’s much easier to do simplified maths while you’re flying and are busy with 100 other things.
@@flyingconsultant It's not an airliner. There's plenty of time to use a calculator, don't you think?
@@purrple.shadows not sure if you fly, but if the weather is not ideal, it can get quite busy in a small plane especially if you don’t have autopilot. I actually get my TOD from ozrunways and don’t calculate in my head. Additionally I don’t ever need to arrive at exact altitude anyway. I usually fly level for a couple of miles before landing. It gives me better view of local traffic.
Oil congealing? No way. The engine that supposedly shock cools is still hot. I agree with the shock cooling worry is a myth and an old GA Aviation wives tale like 23 squared and not leaving the throttle wide open because some kind of way starving it of more air than God is doing at a higher altitude is a good thing.
You may not worry about teaching descent but you are certainly practicing condescend 😝
Novice to you: how do you know how far away from the runway you are?
It's either done using aircraft instruments, eg DME (distance measuring equipment), GNSS (GPS), or visually using dead reckoning (plotting ones position on a chart, cross referencing with ground features if there are any, or by using compass and a stopwatch).
0:44 Formula
1:58 Shock cooling is a myth
Shock cooling is a myth for non-turbo engines. I think with Turbo engines, you need to cool them down.
Cost per rule, between filming, editing, flying, 1000€. Total cost of PPL theory: 100.000€ 😂😂😂
Get a water-cooled engine. Then when the glider releases just close the throttle and point the nose at the runway 😆
The people who taught me to fly taught power off descents, 100 knots at 500 fpm, about right in a PA28. They never discussed where the numbers came from. My Musketeer has an engine monitor and I can see what this does to the CHTs (ouch!) so I do power-on descents. Typically 110 knots, 550 to 600 fpm.
Too much talk prior to the tip.
I literally put the formula/tip within the first 46 seconds. Is your attention span really that short?!
Shock cooling is an old wives tail. Ask Mike Busch.
4:49 you could not just multiply by GS x 5 instead of 10 and then dividing by 2?
5 x 120 = 600