ATPL POF Theory: Coffin Corner ✈ Please like, share and subscribe if you found this video useful and would like to see more :) Comment with future video suggestions bellow!
When I saw "low spd (stall limit)" and "high spd (mach limit)" I was enlightened. That was the only missing information that I needed to fully understand this. Kept seeing "buffet free range" and stuff like that in the tests and never could´ve figured out what it has to do with coffin corner (even though I knew it did).
Just found your channel and mate you are a legend, you're truly helping me a lot with my ATPL studyings. I hope your channel gets to 1 mil subs soon, you deserve it.
According to a a former RAF navigator I knew, this was a major problem with the Vulcan bomber which could not recover from Mach tuck. The aircraft had to stay way below Mach 0.9.
As usual, thank you SO much for this clear, concise, and useful information Ed! It helps me a lot while preparing myself for sitting my ATPL exams in some weeks ahead now... Thanks a million
Your videos are super helpful, mate! I'm studying Aviation engineering currently at university and hope to become an airliner pilot in the next few years after I graduate. Keep it up!
I need clarification. We know that L=Q*CL*S , IAS = How much dynamic pressure is exerted on the airframe, TAS= Free stream velocity and Q=1/2*rho*TAS^2 Let's say 1g stall speed in clean config = 200 knots, if i climb higher and higher and then maintain steady level flight, i'll still be pulling 1g, so why does this stall speed increase with increasing TAS ? Even though i didnt change config, gross weight and load factor !?
There was a video of a captain of a business jet at flight level 510 who was saying there was just 40 knots IAS between stall speed and overspeed, so yeah, pretty close to it.
There is a case in Mexico, not so long ago. I think that happened plus bad weather plus 13 on board; it was a Bombardier Challenger 600 returning from Las Vegas. N601VH
Excellent explanation, as usual. -On the PFD the coffin corner is at 243kts. Isn’t it too slow for the a Boeing 737 at FL380 ? -And also, why is there .78 in violet in the upper part on the speed and .770 in white on the down part? Thank you so much !
The 243 is indicated airspeed or KIAS, true airspeed (not shown) would be somewhere around 450K. This is not the coffin corner. On the speed tape you can see a max KIAS of 259 and a min of 229 or a 30 knot maneuvering range which is actually a lot. If altitude was increased this range would decrease...at some point you would reach the "point" of the chart, that's the corner. Realistically you want to operate will below the point, remember when you bank the aircraft the maneuvering window decreases. The magenta .78 is selected mach number, the white .770 is actual mach number.
Big thank you captain Please why not take the same path of captain Joe and Mentour pilot and teach us enough topics related to aviation because I believe that you will make it sounds easy .
Does that mean that - at such a high altitude - you would only risk stalling the aircraft but not surpassing the VNE risking structural damage as you would "only" stall the aircraft both at a too low and too high speed (given the Mach shock wave increasing drag)?
sorry for making it so complicated, the question was that - at such high altitudes - you could "only" stall the aircraft if gowing faster but not risk structural damage you would risk by overspeeding at say sea level?
@@djordjeandrijasevic6650 overspeed is a structural limitation, so you could damage the aircraft yes. Don't over think it, just know you have to come down from there haha
Hello Captain, is there a way to come out of coffin corner? Will it be a good idea to pitch down idling the power and then recovering like we do in a normal stall?
Sir My dream Is To become A Pilot . I will complete with my 10 class it is base .12 class is need for it. Really Sir You are telling very Important Topics And AlsoYou Are Giving Very Much Motivation Thank you Sir
Hello Ed and audience :) I would need some help please to understand something that still remain unclear to me. Commercial flights fly at a certain altitude for economic reason. Anybody would be able to explain why? As we go higher, air is less dense, meaning less air flowing over the wings, so we need to add thrust to maintain our lift. More thrust doesn't mean more fuel? 🤔
Oh so this is what determines the service cig of an aircraft? I didnt know that! What about a piston plane tho, like a 182, is there also such a thing as coffin corner for them?
Neil GuitarPlayz_YT: It’s called trading altitude for airspeed. Q-Factor only applies where pressure altitude enables its existence. This is not the same thing as moving thrust levers to idle during a power-on stall after take-off (as just one example). In this scenario altitude *is airspeed* and *pitch* is used to control that fair exchange airspeed. Said another way, altitude is Potential Energy which gets converted to airspeed through changes in Pitch Attitude. As long as Gravity remains constant at altitude (and we have reason to believe it wont), for all practical purposes, altitude is airspeed ‘potential’ controlled with pitch attitude. So, yes. Cut the throttles and pitch for airspeed as delta between stall limit and mach limit increases. The stable way to fly out of high Q. Bottom line - stay away from high Q in general.
It is generally recoverable. One good thing about coffin corner is that it only exists a very high altitude and obviously altitude is your friend. You have time to regain control. As with any situation there could be other factors involved that might make it unrecoverable but in general a loss of control at high altitude shouldn't be a big problem if handled properly
To put it simply, as you go higher, the air is less dense so your IAS will read lower and lower. That's why jet planes don't fly according to IAS anymore above FL290 (generally). They use Mach speed instead. Speed of sound is directly affected by temperature. As the temperature decrease with altitude, so will the speed of sound. Example: at sea level ISA, speed of sound is around 661 kts.. as you climb, speed of sound is decreases with decrease of temperature, let's just say 550kts at 35,000ft while indicating M 0.78 and IAS of 240kts etc.. this isn't accurate numbers they're just for the sake of simplicity.
PilotEd Wow, that’s cutting it close. What is the procedure to recover from that situation? Very slowly reduce your altitude? Your videos are very clear, thanks for passing on your knowledge.
PilotEd Your welcome. If your still taking suggestions for future videos, I recently saw the rerun of “Flight”, and wondered if that could be discussed i.e. inverted flight in a airliner?
MMO as displayed on the PFD, is not high speed buffet speed and has no relationship with this phenomenon. MMO/VMO are regulatory speed. You can fly beyond MMO or what is called the extended envelope, without any buffet and you can also experience high speed buffet below MMO, if the wing loading is high enough. To understand MMO/VMO study part 25.161, 25.173, 25.175, 25.177, 25.251, 25.253, 25.255, 25.305, 25.333, 25.335, 25.337, 25.341, 25.349, 25.351 and understand VD/MD speeds as the upper boundary of the extended envelope, and then read Supersonic DC8 to understand the experience beyond the extended envelope and redo the video, so that you don’t miss lead.
Simply put, the higher you climb, the faster you reach the speed of sound. Air traveling at speed of sound causes shockwaves to form causing massive drag that leads to a high-speed stall.
if you reach coffin corner you cannot speed up or slow down, the ONLY WAY IS DOWN, once you start to descend you have a greater margin of speed both ends :) thanks for watching
![Coffin Corner Explained - [How YOU can spot the coffin corner by looking at the Airspeed Indicator]](http://i.ytimg.com/vi/KPJxz39Ieao/mqdefault.jpg)
![Coffin Corner Explained - [How YOU can spot the coffin corner by looking at the Airspeed Indicator]](/img/tr.png)
![ไปอยู่ไสมา - ช๊อปเปอร์ โตเกียวมิวสิค [ OFFICIAL MUSIC VIDEO ]](http://i.ytimg.com/vi/sWuVNbRTJbc/mqdefault.jpg)
This channel is still underrated. Deserves way more views ! He explains so well complex concepts. Great job, hoping to see many more.
I bet if my wife did the videos id get more views! prob if I could be bothered to edit them fancy to haha short sharp and to the point! :)
Share his video as much possible
When I saw "low spd (stall limit)" and "high spd (mach limit)" I was enlightened. That was the only missing information that I needed to fully understand this. Kept seeing "buffet free range" and stuff like that in the tests and never could´ve figured out what it has to do with coffin corner (even though I knew it did).
Just found your channel and mate you are a legend, you're truly helping me a lot with my ATPL studyings. I hope your channel gets to 1 mil subs soon, you deserve it.
According to a a former RAF navigator I knew, this was a major problem with the Vulcan bomber which could not recover from Mach tuck. The aircraft had to stay way below Mach 0.9.
Awesome explanations. Regards
Thanks man
As usual, thank you SO much for this clear, concise, and useful information Ed!
It helps me a lot while preparing myself for sitting my ATPL exams in some weeks ahead now...
Thanks a million
You just got a new subscriber. Have been sitting with the ATPL book now for a while but this video was so much better!
thanks for that, a perfect explanation of the coffin corner to respond PERFORMANCE ATPL questions.
Finally got a simple brief explanation about a well spoken phenomena. Now I'm able to understand that part of High Speed Flight, thanks!
glad to help :)
This video worth more than 100 pages of ATPL books. Keep going! Great video! Hope to see many more
Your videos are super helpful, mate! I'm studying Aviation engineering currently at university and hope to become an airliner pilot in the next few years after I graduate. Keep it up!
cheers and see you soon in the skies :)
A complex topic explained concise and engaging. Good one :)
thank you :)
Subbed because of that drawing. And the great explanation too
thanks man :)
Just studied now on POF on my ATPL studies, very nice explenation thanks!
thanks mate! very good explanation,keep it up with those videos ;)
Very clear. Love it. 👍
Amazing video, thanks for sharing and spreading knowledge!
Learning this for Flight Sim 2020. Thanks for the information o7
Can't thank you enough ! .. Keep these ATPL vids coming !
thanks so much, more on the way :)
Hi PilotEd, this explenation of Coffin Corner is very interesting! Now I'm following you and your work! Have a good day
cheers for watching :)
I need clarification. We know that L=Q*CL*S , IAS = How much dynamic pressure is exerted on the airframe, TAS= Free stream velocity and Q=1/2*rho*TAS^2
Let's say 1g stall speed in clean config = 200 knots, if i climb higher and higher and then maintain steady level flight, i'll still be pulling 1g, so why does this stall speed increase with increasing TAS ? Even though i didnt change config, gross weight and load factor !?
Your videos are absolutely fantastic. Thank you so much for making them. Keep them coming!
cheers :) slowly more will be on their way :)
Tks man! What a nice explanation!
Hi, how come you never mentioned the 1.3g manoeuvre ceiling as this is always below the aerodynamic ceiling (coffin corner)
Keep it up! Nice work!
thanks for watching
There was a video of a captain of a business jet at flight level 510 who was saying there was just 40 knots IAS between stall speed and overspeed, so yeah, pretty close to it.
There is a case in Mexico, not so long ago. I think that happened plus bad weather plus 13 on board; it was a Bombardier Challenger 600 returning from Las Vegas. N601VH
This was very helpful, thank you!
The upper boundary is MMo but not high speed buffet,which occurs quite a bit higher.
Simple, easy to understand. Thank you
Excellent explanation, as usual.
-On the PFD the coffin corner is at 243kts. Isn’t it too slow for the a Boeing 737 at FL380 ?
-And also, why is there .78 in violet in the upper part on the speed and .770 in white on the down part?
Thank you so much !
The 243 is indicated airspeed or KIAS, true airspeed (not shown) would be somewhere around 450K. This is not the coffin corner. On the speed tape you can see a max KIAS of 259 and a min of 229 or a 30 knot maneuvering range which is actually a lot. If altitude was increased this range would decrease...at some point you would reach the "point" of the chart, that's the corner. Realistically you want to operate will below the point, remember when you bank the aircraft the maneuvering window decreases. The magenta .78 is selected mach number, the white .770 is actual mach number.
Big thank you captain
Please why not take the same path of captain Joe and Mentour pilot and teach us enough topics related to aviation because I believe that you will make it sounds easy .
Piloted got a really complex message across in four minutes! A great lesson in presentation even if you don't pilot.
very helpful thanks for your sahre .
Really good video! Such a clear explanation, thanks
thank you cap! helped me a lot.
Another very good video well explained thank you
your welcome thanks for watching
I could follow that as a non-pilot. Brill.
Smooth!!
What about If you have a TCAS RA at the absolute ceiling!?
I always thought the speed of sound varied with density as well. I.e, sound is faster in water than air because air is less dense than water.
it does, but doesnt affect it as much as temp, they are all related really, colder air is denser :)
Thank you.
top marks
c'est magnifique
perfect explanation. thanks a lot !
perfect xp, bst regards!
the best explanation, thank you
The number of times I've flown on passenger jets without knowing this. Next time I'll get a 172. Or a bus.
@3:27 perfect succinct explanation!
THanks mate ;)
PilotEd You're welcome!
Thank you Capt. A new concept learned to day.
glad to help :)
complex subject explained simply. thank you
thanks more on the way soon
You state that an aircraft will stall at a constant IAS. An aircraft can stall at ANY IAS and is related to AoA (and G loading).
Thank you very much for such a useful explanation.
your very welcome thanks for watching
Great video. I like your description.
thanks for watching !
Does that mean that - at such a high altitude - you would only risk stalling the aircraft but not surpassing the VNE risking structural damage as you would "only" stall the aircraft both at a too low and too high speed (given the Mach shock wave increasing drag)?
sorry mate don't understand the question? at coffin corner we can easily stall the aircraft (high or low speed stall)
sorry for making it so complicated, the question was that - at such high altitudes - you could "only" stall the aircraft if gowing faster but not risk structural damage you would risk by overspeeding at say sea level?
@@djordjeandrijasevic6650 overspeed is a structural limitation, so you could damage the aircraft yes. Don't over think it, just know you have to come down from there haha
Thanks you Sir
U2 flies around such region
so, at which altitude coffin corner its normally reached?
Thanks , i wasn't know about that ❤
Sir can u make a video abt , buffet and it's relationship with the air and wing
Thank you; well formulated.
cheers:)
@Piloted why are we not considering EAS here? The pilot gets an indication of EAS on his instrument... Not all are have PFD like TAS display
Because EAS is considered by aircraft's computers in order to find TAS and Mach number which are the speeds as pilots we care about.
once i saw the pic i was like OOOOH makes sense
Hello Captain, is there a way to come out of coffin corner? Will it be a good idea to pitch down idling the power and then recovering like we do in a normal stall?
you have to loose altitude, then the margins become greater :)
Thanks you I was confuse a little bit but now it’s really clear
glad to help
So, how to actually get out of this corner?
Amazing channel bro.. I'll pass my exams b coz of you... Please do make more videos
more on the way mate, stay tuned, Just a hobby for me :)
Sir My dream Is To become A Pilot . I will complete with my 10 class it is base .12 class is need for it. Really Sir You are telling very Important Topics And AlsoYou Are Giving Very Much Motivation Thank you Sir
Very much impossible to 'need for it' in your 12 class. Good video indeed but you just talk too much.
Really helpful for one more time !! Thank you!!
very welcome
PilotEd could you also make a video regarding fuel policy concerning the ATPL exams ??
@@evantsiskakis3358 I have already check my video on fuel definitions
the "wuu" tho .
Hello Ed and audience :)
I would need some help please to understand something that still remain unclear to me.
Commercial flights fly at a certain altitude for economic reason. Anybody would be able to explain why?
As we go higher, air is less dense, meaning less air flowing over the wings, so we need to add thrust to maintain our lift. More thrust doesn't mean more fuel? 🤔
less dense air equals less resistance/higher TAS/ and less fuel needed as less air to maintain correct ration 15:1 aprox :)
@@PilotEd thanks a lot for your answer. Greatly appreciated :)
Sorry again, but I thought more altitude meant more parasite drag. Not enough shall I suppose..
Awesome explanation.
thanks man
Oh so this is what determines the service cig of an aircraft? I didnt know that! What about a piston plane tho, like a 182, is there also such a thing as coffin corner for them?
yes and no, service ceiling is also related to engine power. :) a 182 cant really get into trouble that high lol
Call 911 For Cookies I
Interesting. I take it coffin corner is not a concern for supersonic aircraft?
of course it is! any aircraft. just supersonic ones will have different wing designs :)
Why do you fly at 243kts at 38000ft ?
Airliners cruise at around +/- 500kts, how can they stall at this speed ?
Thank you very much, cool video!!
have a look at the mach number my friend :) to understand the why speeds change with altitude have a look at my speed vs altitude video :)
Ok thanks, so 243 is your IAS not your TAS ?
at :)
OMG you seriously? why bother to ask if you can't even read a PFD.
Nicely explained, thanks.
You look a lot like clark kent 🫡🫡🫡
Does coffin corner effect small general aviation planes that flies nowhere near the speed of sound?
No
top of the pyramid
Question when operating at this close +/- 20 or so kts. How do you decend without picking up speed or stalling when powering down for decent ?
close the thust levers, and control your speed with the pitch ;)
*CLOSE*?????? SO YOU IDLE THE THRUSTS WHEN DESCENDING???
Neil GuitarPlayz_YT:
It’s called trading altitude for airspeed. Q-Factor only applies where pressure altitude enables its existence. This is not the same thing as moving thrust levers to idle during a power-on stall after take-off (as just one example).
In this scenario altitude *is airspeed* and *pitch* is used to control that fair exchange airspeed. Said another way, altitude is Potential Energy which gets converted to airspeed through changes in Pitch Attitude.
As long as Gravity remains constant at altitude (and we have reason to believe it wont), for all practical purposes, altitude is airspeed ‘potential’ controlled with pitch attitude.
So, yes. Cut the throttles and pitch for airspeed as delta between stall limit and mach limit increases. The stable way to fly out of high Q.
Bottom line - stay away from high Q in general.
Beautiful explanation 👌🏻
thank you :)
sir make a video of Dutch roll and by the way how to survive from coffin corner ?
dutch roll, thats a good one thanks, escape from coffin corner is easy mate, go down! :)
I imagine you just descend until you out out of coffin corber
Very useful!!!
thanks :)
Cough in corner.
is Coffin corner referring to a point/angle on the surface of the wing ?
don't really understand the question sorry
@@PilotEd umm , does it mean it's a certain area in each wing ?😀
Catch 22 corner
Thanks!
your very welcome
Will the resulting stall always result in a high altitude spin and is it recoverable in a large commercial airliner?
ive never tried it so not sure lol
It is generally recoverable. One good thing about coffin corner is that it only exists a very high altitude and obviously altitude is your friend. You have time to regain control. As with any situation there could be other factors involved that might make it unrecoverable but in general a loss of control at high altitude shouldn't be a big problem if handled properly
well said :) thanks
great chanel bro
thanks man, XD
So, how can a acft fly faster than the sound without the shock wave appears?
pls help me, i had a very bad flight theory teacher
Different wing design to minimise drag, and ALLOT of power to overcome the drag :) its not impossible its just not efficient
@@PilotEd Got it, tks! greetings from Brazil!
I can't get it. When you are high you should speed up bcs air is less condensed, so why the shockwave speed is lower?
Shadow_of_STLKR because air is less dense? And wings... kinda need that airflow to produce lift
To put it simply, as you go higher, the air is less dense so your IAS will read lower and lower. That's why jet planes don't fly according to IAS anymore above FL290 (generally). They use Mach speed instead.
Speed of sound is directly affected by temperature. As the temperature decrease with altitude, so will the speed of sound.
Example: at sea level ISA, speed of sound is around 661 kts.. as you climb, speed of sound is decreases with decrease of temperature, let's just say 550kts at 35,000ft while indicating M 0.78 and IAS of 240kts etc.. this isn't accurate numbers they're just for the sake of simplicity.
I know that this is an old video, but I’m curious how close commercial aircraft get to the coffin corner at cruising altitude
well ive been up so close that I have maybe a 5knot margin
PilotEd Wow, that’s cutting it close. What is the procedure to recover from that situation? Very slowly reduce your altitude? Your videos are very clear, thanks for passing on your knowledge.
@@curvebal you can only come down from that yes, have to keep your eye on the speed. and thanks for watching
PilotEd Your welcome. If your still taking suggestions for future videos, I recently saw the rerun of “Flight”, and wondered if that could be discussed i.e. inverted flight in a airliner?
@@curvebal lol yeah thats not reality im afraid
So why not just fly lower then
MMO as displayed on the PFD, is not high speed buffet speed and has no relationship with this phenomenon. MMO/VMO are regulatory speed. You can fly beyond MMO or what is called the extended envelope, without any buffet and you can also experience high speed buffet below MMO, if the wing loading is high enough. To understand MMO/VMO study part 25.161, 25.173, 25.175, 25.177, 25.251, 25.253, 25.255, 25.305, 25.333, 25.335, 25.337, 25.341, 25.349, 25.351 and understand VD/MD speeds as the upper boundary of the extended envelope, and then read Supersonic DC8 to understand the experience beyond the extended envelope and redo the video, so that you don’t miss lead.
Why does the high speed stall decrease with increasing altitude
true airspeed for a given Mach number generally decreases with altitude. :)
Simply put, the higher you climb, the faster you reach the speed of sound. Air traveling at speed of sound causes shockwaves to form causing massive drag that leads to a high-speed stall.
Hello captain! The last video doesn’t work I think there is an issue with upload check it please !
re-uploading now sorry give it 10 mins :) thanks for watching
PilotEd thanks and it is pleasure!
If I reached coffin corner I have to lose altitude at constant ias to leave this state ?
Or I will stall any way if I allowed aircraft to achieve this altitude ?
if you reach coffin corner you cannot speed up or slow down, the ONLY WAY IS DOWN, once you start to descend you have a greater margin of speed both ends :) thanks for watching
at 2:30 you mentioned a red line on the PFD. don't see a red line on the PFD.
It's the dashed red line on the airspeed tape. (left side of the PFD)
They're the black and red bars above the magenta speed bug
I dont understand english , I understand portuguese only!
press 'c' and try to use legends. Helps a lot.
Explanation too complicated