Mach To Knots: Why Do We Fly Mach Number At High Altitudes?
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- Опубликовано: 29 сен 2024
- Mach to Knots: What is the difference between the Mach Number and the Airspeed.
By the end of this video, you will know what mach number (MN) is, what's the difference between MN and Airspeed and why we fly mach number and not Airspeed at high altitudes.
The mach number is a true airspeed indication given as a percentage of the local speed of sound.
According to the standard atmosphere at the mean sea level, the speed of sound is 661kt.
If you are flying with a True Airspeed of 661kt you will be flying at Mach 1.0 and, if you fly at 330kt your mach number will be 0.5.
In order to calculate the MN you have to divide the True Airspeed by the Local Speed of Sound (LSS).
The LSS is not constant and varies with the temperature, the lower the temperature the lower the Local Speed of Sound.
So, at the mean sea level, the LSS will be higher than the Speed of Sound at high altitudes since the temperature is lower.
During the initial part of the climb, the Jet Airliners fly airspeeds and than when reaching high altitudes they change and fly Mach number.
This is so because if you fly at constant Airspeed you will overshoot Mach 1 at high altitude thus going into supersonic speeds range creating the shock wave and all the problems associated with that.
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Disclaimer:
THIS VIDEO IS FOR ENTERTAINMENT PURPOSES ONLY.
NOT FOR REAL-LIFE OPERATIONS.
PLEASE REFER TO THE OFFICIAL MANUAL AND DOCUMENTATION.
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![Critical Mach Number Explained - [Do You Know What Is The Overspeed Clacker?]](http://i.ytimg.com/vi/JeIo_gxo49Y/mqdefault.jpg)
![Critical Mach Number Explained - [Do You Know What Is The Overspeed Clacker?]](/img/tr.png)
Don't forget to comment the video with your questions and thoughts! Have a great day!
Here is a question: as a pilot how do you fly the airplane during rough air above the crossover altitude? How do slow the plane, to mach, to IAS, or to some average imaginary speed or to the middle of the higher and lower bands?
Thanks
you have a special talent to explain hard concepts and make it simple to understand, greetings from chile 🇨🇱
Hey, many thanks for your support!! I'm glad to see you like the videos..don't hesitate to ask me any questions when watching the videos of the channel👍 I wish you a great day!
Hey man, thanks for the vids and explanations, really nice job!👍🏼⭐
But please don't say "ok?" that much.. it's irritating and takes away the good effect of your input!!
Thanks for your feedback
Salute
Greatly appreciate your effort captain. One of the best aviation channels I've come across so far!
Hey, I hope you are doing great!! Many thanks for watching and the great comment!
Don't hesitate to ask me any question you may have when watching the rest of the videos
Have a great day
Gabriele
Pilotclimb
My brain hurts but thank you! I finally understand the purpose of switching to Mach numbers vs IAS.
You are very welcome!
3:00 to link the Local Speed to Sound to temperature, isn't entirely correct. It has to do with Air Density and therefore Altitude. Take MSL at Antarctica; where the Local Speed of Sound is quite high.
I think your hand movements broke Mach 1 on several occasions :) Thanks for the explanation, I appreciate the time you took to explain this.
Thanks for the video and the awesome explanation. Helped me a lot.🇩🇴
Now one last question. ¿At what level normally do the pilot switch from knots (indicated speed) to mach number in order to regulate the speed during the climb? Is it FL250, FL290 or you have any other thing to take into consideration ? Thank you in advance.
Captain. Congrats for your help in share technical knowledge.
I have a doubt. Why is it important to know the minimum level of tropopause ?
Many thanks, it is related to temperature above the troposphere the ELR stops.
@@PILOTCLIMB thanks captain a lot. But in relation with aircraft performance, Is there any influence?
Thank you Captain. Helped a lot!
You are very welcome!
captain why not only use Knot speed
Hey many thanks for watching!! If you climb at contant knots speed during climb you will end up having problem with your critical Mach number. Search on my channel the videos where I explain how does this work and then let me know if you still have any questions👍
Just as a casual sim pilot on descent I tend to switch back to knots IAS usually even well before reaching FL180. With a turboprop that only goes to FL250-300, I usually keep it on knots even if it can switch to mach. Is that considered an acceptable option, or are they fairly adamant about using mach above FL180?
Thank you for information
You are very welcome!
Your practical examples make it very useful to get the concept clear. Thanks
Hey, I'm very happy you understood the topic of the video!!
Many thanks for watching!!
I wish you a great day
Gabriele
Pilotclimb
This is absolutely the best piloting channel on RUclips! Thank you!
I'm glad you are finding my channel interesting!! Many thanks for your great support
If I have to fly with a good rate of climb while in Mach number and ATC says to meet a constraint FL by this waypoint, should I switch to IAS because my IAS will keep decreasing and may go below the green dot speed in A320?
Hey, great question, I would stay on Mach Number at high altitudes, so you are protected.
In terms of supersonic jets, they usually quote the max speed in terms of Mach. Is that constant at all altitudes, or only at a specific altitude (which would be a lot less impressive if it was something like 60000ft)?
You have 2 max speeds, one expressed in knots and one in mach number. The MMO ( Max mach number) is a constant value.
Nice video, it would be better to make a graph of the two instances of aircraft, climbing at a constant mach number and constant indicated airspeed
Thanks for watching and the feedback
This is great! Such a great help. I’m currently going from piston to jets and I’ve never considered any of this before.
Glad to read that
Really a great video....understood each and everything...by now about mach number....thank you captain alot....greetings from india❤️✌️
Nice to see you are watching from India!!! Many thanks for your support
Wow, It is a great explanation. It helped me a lot to understand. Thank you.!!!
You are very welcome!!
This is really useful and you've made it really easy to understand! Thank you!
Glad to read that! You are very welcome!
I never knew it was the temperature and NOT the air pressure that controls the mach number, and I majored in physics.
Thanks for watching!
How come I'm subscribed to you and i never never see your videos on my feed. They are so good.
My pleasure to see you like my videos! The more you watch them the more they will pop up on your feed, that's how RUclips works. I wish you a great day!
Very interesting. Thx. Never found a tutorial explaining that. 👍
You are very welcome!! I'm glad you liked it
Dear Caption
Thanks for sharing your knowledge and experience.well done.is there a way to contact you.email/phone please
Regards from UK
Hey, you are more than welcome..I'm glad you find the videos useful..you can send me an email to info@pilotclimb.com 👍
@@PILOTCLIMB
Thank you very much
We talk via email
Great explanation Captain ! On reaching T/D , do we put the thrust lever idle until touch down ?
I'm glad you liked it!! From the TOD you try to keep the thrust idle for as long as you can, however, even if your descending is perfect you still need to add thrust on the short final in order to fly with landing flaps.
Explained in a very simplified way,thanks,mach meter used not so much a speed indicator but a warning device to indicate an imminent problem due to shockwave,so it’s an indicator of current airflow condition
Many thanks for watching and the comment!! I'm glad you liked the video
Another excellent video, well explained as always. I knew that the change over button (C/O) would switch from IAS to MACH but I couldn't think of any reasons behind that. This video really makes it clear now, it does make sense to switch from one to the other during climb and descent procedures. The question here is : At which altitude does the C/O happen automatically in the B738? I think I read somewhere in the technical site of the 737-800 that it should happen automatically when you reach FL260, am I correct? Thanks again captain, I was very lucky when I discovered your channel, you definitely deserve TONS more likes and TONS more views ans subscribers.
Many thanks for your great support!! The change occurs approximately at FL260 as you mentioned!! 👌
@@PILOTCLIMB
But why at FL260?
Is there an exact altitude number where the change happens?
Great video, I subscribed. I wonder if you would be interested if we ask certain ATPL exam questions and perhaps you may be interested in providing an explanatory video. It would be great thanks.
Hey, welcome on-board! I'm glad you liked the video! What questions do you have?
@@PILOTCLIMB mostly related to fuel calculations in flight planning how to perform them accurately and efficiently as we don’t have enough time to take it easy In our official exams to go through every question. Perhaps even mass and balance as they are somewhat interconnected. Thank you!
Good Day Capt Gabriele,
I saw 2 pitot tubes on left and right on near tail(vertical stabilizer area) on B737.,what is the purpose/function of this 2 pitot tube? Normally to measure speed B737 have 3 pcs on the nose (2 on left and 1 on right)
Hey, grerat questions, those two pitot tube are for the elevator feel and centering unit, basically they take the airspeed infos and send them to the elevator feel and centering unit that simulates an artificial load on the Yoke of the pilots. The faster you fly the higher will be the force required to move the Yoke and viceversa.
@@PILOTCLIMB Thanks for explanation Capt Gabriele, i understand they are 2 pcs, 1 in operation and 1 in standby as back up/redundancy if other failed. Is it right?
Wish you a great day ahead.. 👍👍
Good Day Capt Gabriele, is there a similiar system( like elevator feel and centering unit) for the rudder in B737? I mean here for high speed a rudder pedal is more heavier to move/less deflection and in low speed lighter to move/more deflection?
great explanation,so informative!
Thank u captain!
You are welcome! Glad the video helped you!
Thanks for the great explanation 🇿🇦
You are very welcome!
And your are italian..... :)
🇮🇹
Thank so very much Captain !!
You are very welcome! Thanks for watching
Absolutely fantastic explanation 🤛🏼
Many thanks for your great comment! Don't hesitate to ask me any questions when watching the rest of the channel videos. Have a great day!
Hey, nice example with the PFD visualisation! But is it that fast of a decrease of the IAS? Because the aircraft was only climbing at a rate of 1400 FPM?
Hey, I hope you are doing great!! I'm glad you liked the video!!
The part of the video about the Simulator example is accelerated, otherwise it would have taken long time before reaching the cruise level.
I think I point this out during the video..
Let me know if I answered your question..
Have a great day
Gabriele
Pilotclimb
@@PILOTCLIMB Thank you, it makes sense. I didn't "notice" the altitude going up that fast, only the airspeed going down fast
@@gigibostan Cool!!! Don't hesitate to ask me any question you may have when watching the rest of the videos!!
Have a great day!!
Im so glad to have your videos captain.. it refreshes all my learnings in flying. Im an airbus a320 rated pilot. Completed my training a year ago but unfortunately this pandemic did not give me the opportunity to apply in the airlines. Thanks to your videos im learning so much more and for sure it will be of big use once aviation is back on track and i’ll do my recurrency.. Hope this channel will earn millions of subscribers coz it helps a lot of pilots out there.
Thanks for watching and the kind comment! I'm glad to see the videos are helping you! I wish you a great day!
Interested to know, did you manage to get a job in the end?
Great explanation Captain👍
Thanks for watching!
Great explanation, thanks captain!
Good Day Capt,which button on MCP we push to switch from IAS to Mach Number ?...I have a question could we just push speed button on MCP and set a limit for airspeed for example at FL 400 we calculated speed of sound 400 Knot(just example) then we input 280 Knot in speed window on MCP as our limit ?
Hey, I hope you are doing great!!
You can Push the C/O button that is just above the speed button. You could use the speed as limit, however is not recommended, because the local speed of sound can vary depending on the temperature and the temperature at various level varies day by day. So the safiest and easiest way is just to fly Mach Number at high altitudes. Let me know if I answered your question..
Excellent explanation Captain! Do you use mach numbers for GA aircraft or is this something that is only referred to for very high speed aircraft? Just that I haven't ever heard GA pilots or CFIs mention this.
Hey, many thanks for watching and the comment!! Mach number is for high altitude and fast planes. Private jets also use Mach number at high altitudes and Small GA planes (like the cessna 172) fly using knots..
Actually our passenger jets were designed to travel 1,140 miles per hour and also designed to be modified quickly to carry bombs.
A little secret that many many many people don’t know.
Thank you
Thanks for this interesting info!!