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What Happens If An Aircraft Over Flies 40,000?  
User currently offlineAirmale From Botswana, joined Sep 2004, 376 posts, RR: 1
Posted (11 years 1 month 1 week 6 days 4 hours ago) and read 32388 times:

I think thats the ceiling, so what could happen if they exceed that height?


.....up there with the best!
42 replies: All unread, showing first 25:
 
User currently offlineDonder10 From Canada, joined Oct 2001, 6659 posts, RR: 22
Reply 1, posted (11 years 1 month 1 week 6 days 4 hours ago) and read 32408 times:

A lot of the modern ones have ceilings of around 42,000ft.I have Ryanair flights at 40,000feet before!Some 747SPs have been upto 45,000ft!

User currently offlineGroobster From United Kingdom, joined May 2001, 310 posts, RR: 0
Reply 2, posted (11 years 1 month 1 week 6 days 4 hours ago) and read 32398 times:

Whilst on a flight on New Years Eve from MEL to SYD on an A332 we had to rise to 41000ft to avoid heavy turbulence.

Can't say anything stranged happen to us!



Next flights: MAN-IST-AUH-MAN
User currently offlineAirmale From Botswana, joined Sep 2004, 376 posts, RR: 1
Reply 3, posted (11 years 1 month 1 week 6 days 3 hours ago) and read 32431 times:

And if they exceed 45,000 or more?


.....up there with the best!
User currently offlineZrs70 From United States of America, joined Dec 2000, 3099 posts, RR: 9
Reply 4, posted (11 years 1 month 1 week 6 days 3 hours ago) and read 32487 times:

The air is too thin to support most aircraft at high altitudes. The plane would need increased speed. Fly too high, and the craft would most likely stall.


14 year airliners.net vet! 2000-2013
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 5, posted (11 years 1 month 1 week 6 days 3 hours ago) and read 32407 times:

Cabin pressure is often the altitude-limiter, not airplane performance.

User currently offlineTjwgrr From United States of America, joined Mar 2000, 2415 posts, RR: 3
Reply 6, posted (11 years 1 month 1 week 6 days 2 hours ago) and read 32233 times:

737NG's and 757's routinely cruise up to FL 410, 767's up to FL 430.


Direct KNOBS, maintain 2700' until established on the localizer, cleared ILS runway 26 left approach.
User currently offlineMark_D. From Canada, joined Aug 2001, 1447 posts, RR: 5
Reply 7, posted (11 years 1 month 1 week 6 days 2 hours ago) and read 32214 times:

Note that --depending upon whom you ask and what variant it is and payload it's carrying-- the fairly-standard-subsonic-wing-design B-52 bombers have advertised service ceilings of as much as 56 000 ft.


I think this is an interesting article, about airliners' environmental control systems:

http://www.boeing.com/commercial/cabinair/ecs.pdf


Figure 10 near the end shows "cabin altitude" getting rather rarified, when aircraft altitude gets above 40 000ft.

[Edited 2003-06-03 23:08:42]

User currently offlineBellerophon From United Kingdom, joined May 2002, 583 posts, RR: 59
Reply 8, posted (11 years 1 month 1 week 6 days 2 hours ago) and read 32131 times:

Airmale

The maximum altitude a civil airliner is certificated to fly at is determined during flight testing, and is imposed because the aircraft has come up against any one of a number of different limitations, depending on the design of the aircraft, its wing, its engines or its cabin environmental systems.

Just to give a few examples:

  • The aircraft engines may not be producing sufficient thrust to enable it to climb any higher.


  • The aircraft wings may not be capable of providing adequate lift at a higher altitude.


  • The Mach Number might become too high, causing undesirable aerodynamic effects.


  • The maximum and minimum speeds may be too close together at a higher altitude


  • If the Cabin pressure were to fail at high altitude, there may not be adequate Oxygen pressure available in the emergency drop down masks.


  • B777236ER raised an important and increasingly common limit, that of cabin air pressure. The air pressure in the passenger cabin must not be allowed to fall below a minimum value, equivalent to a maximum Cabin altitude of 8,000 ft (I think), under both JAA & FAA regulations

    If the cabin altitude is already at the maximum permitted, and the aircraft then climbs, the differential pressure (the difference between the pressure inside the cabin and the air outside the aircraft) will rise as the outside air pressure decreases.

    When you reach the maximum differential pressure, typically around 8 to 9 psi, you cannot climb any higher without breaking one of those two limits.

    I hope these give you some idea of the varied reasons that can determine how high an airliner is allowed to fly, and why it is not a good idea to exceed the limit. There is even one airliner where the maximum altitude can be limited by the temperature of the nose!

    Provided that the aircraft is certificated to fly above 40,000 ft - and many now are, with one being cleared to fly at 60,000 ft - it will be perfectly safe up there, and nothing untoward will happen.

    However, deliberately flying any aircraft above its maximum certificated altitude, unless you are a qualified test pilot on a well planned test flight, is one of the dumbest things you can do whilst airborne.

    Regards

    Bellerophon


    User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
    Reply 9, posted (11 years 1 month 1 week 6 days ago) and read 32048 times:

    A B52 is not going to fly at 56,000'.

    It's not possible.

    As altitude increases, indicated airspeed decreases.

    As altitude increases, temperature decreases to a standard -56 degrees C.

    It is not uncommon to see -65 degrees C or colder in a non-standard atmosphere.

    Consequently, to maintain an indicated airpspeed at higher altitudes, true airspeed (or equivalent Mach number) must increase. If it doesn't, the IAS decreases to the point the aircraft stalls. The B52 is a 1950's technology airframe. It is not capable of high Mach capability. Even with ISA -20, the Mach number required to maintain an IAS > Vs will exceed the B52's Mcrit.

    Especially given the ancient technology of their 8 pure turbojets. The engines might be willing (flat out) but the airframe is wanting...

    Original Question: The B767 is certified to fly at FL420. Concorde is certified to (I think) FL 650. Rembember though that Concorde cruise climbs at M2.0



    User currently offlineRedngold From United States of America, joined Mar 2000, 6907 posts, RR: 45
    Reply 10, posted (11 years 1 month 1 week 6 days ago) and read 32048 times:

    But... 45,000 ft. is approaching that coffin corner for a lot of aircraft. They MUST slow down or change AOA to remain stable in flight. Otherwise you get an incident like that Northwest Airlines 727 that took a dive out of the sky over Michigan.

    redngold



    Up, up and away!
    User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
    Reply 11, posted (11 years 1 month 1 week 6 days ago) and read 31968 times:

    It's because the higher you go, the speed margin is minimal. You must be very careful to ensure airspeed does not drop too much or you might not have enough thrust to increase the speed back cruising speed for example. And the higher one goes, the KIAS drops, so it's closer to stalling.


    Boeing747 万岁!
    User currently offlineMark_D. From Canada, joined Aug 2001, 1447 posts, RR: 5
    Reply 12, posted (11 years 1 month 1 week 5 days 23 hours ago) and read 31907 times:

    Well sites like this claim 55 000 ft (sorry, I guess I had remembered incorrectly with the 56 000 number)

    http://www.aerospaceweb.org/aircraft/bomber/b52/index.shtml

    But then writers like this guy mention 50 000 (and says they never went that high anyway)

    http://www.jimclonts.com/bio.htm


    Airframe supposedly able to handle Mach .91



    User currently offlineHmmmm... From Canada, joined May 1999, 2104 posts, RR: 5
    Reply 13, posted (11 years 1 month 1 week 5 days 23 hours ago) and read 31902 times:

    At more rarefied altitudes, an airliner is in an environment that is very unforgiving of a sudden change in AOA. The aircraft could lose stability and control very easily and go into a nose dive. It's happened. The higher you go the less air to ride on, the easier it is to lose control and the harder it is to recover immediately.

    If you have MS Flight simulator, program your aircraft for a very rarefied altitude and watch what happens when it loads. The plane will tumble and drop like a rock and you will not be able to recover until you get down to lower altitudes. I once did this with the soar plane, I loaded it in at 80,000 ft, and the bloodly thing tumbled wildly until I got down to 45,000 ft. simply because there was not enough air to ride on. If you were to magically insert an airliner at, say, 80,000 ft, it would plummet like a rock. The dynamic forces would probably destroy it before it could recover at a lower altitude.



    An optimist robs himself of the joy of being pleasantly surprised
    User currently offlineBrons2 From United States of America, joined Sep 2001, 3007 posts, RR: 4
    Reply 14, posted (11 years 1 month 1 week 5 days 23 hours ago) and read 31925 times:

    Coffin corner is the reason, you get to a point at higher altitudes that the margin between a stall (as IAS decreases) and overspeed (mach too high) becomes very, very small.


    Firings, if well done, are good for employee morale.
    User currently offlineYikes! From Canada, joined Oct 2001, 284 posts, RR: 1
    Reply 15, posted (11 years 1 month 1 week 5 days 23 hours ago) and read 31874 times:

    AIRLINERS CAN'T EXCEED MACH 1.0

    (Except for Concorde)

    Mach 1.0 is a Brick Wall. In fact, it is less than 1.0, usually in the range of .90

    Given that fact; given that the B52 airframe is a < M1.0 airframe ; given the old generation engines (engine inlet ducting needs to be specialized to exceed M1.0 too), yadda yadda...

    You might want to take this over to the Tech forum...


    User currently offlineAA717driver From United States of America, joined Feb 2002, 1566 posts, RR: 13
    Reply 16, posted (11 years 1 month 1 week 5 days 20 hours ago) and read 31751 times:

    I've seen aircraft at 450. I've been to 410 a few times in the 757. The 767 will do 430 but it has to be really light. I think the GIV's and GV's can do 510.

    It's not like Icarus, you know... Big grin TC



    FL450, M.85
    User currently offlineIMissPiedmont From United States of America, joined May 2001, 6277 posts, RR: 34
    Reply 17, posted (11 years 1 month 1 week 5 days 19 hours ago) and read 31667 times:

    But Yikes!, Mach is mach period, never 0.90 mach or 1.07 mach.

    And there are indeed several biz jets certified to fly in the low 50s.



    Quit calling an airport ramp "Tarmac" and a taxiway "runway".
    User currently offlineDerekf From United Kingdom, joined Feb 2001, 890 posts, RR: 0
    Reply 18, posted (11 years 1 month 1 week 5 days 12 hours ago) and read 31477 times:

    Yikes!
    You are wrong. A DC-8 exceeded Mach 1 in a dive during a test flight. There are also rumours about the VC-10.
    Mach 1 is not a barrier - thats what everyone thought in the 1940s. BTW I've been to 45000ft in a 125 where we had only 210kts and 0.8M.

    D



    Whatever.......
    User currently offlineMr.BA From Singapore, joined Sep 2000, 3423 posts, RR: 22
    Reply 19, posted (11 years 1 month 1 week 5 days 11 hours ago) and read 31459 times:

    And does anyone recall the China Airlines B747SP which survived the dived through Mach1.0?


    Boeing747 万岁!
    User currently offlineB747skipper From , joined Dec 1969, posts, RR:
    Reply 20, posted (11 years 1 month 1 week 5 days 11 hours ago) and read 31450 times:

    Surprised to see this question here - why not Tech-Ops...?
    xxx
    The "ceiling" (maximum operating altitude-level) is a certification number...
    For transport airplanes (airlines) it is generally an altitude limit for pressurization, that is, maintaining at least 8,000 feet (2,500 meters) equivalent pressure in the cabin...
    xxx
    Many transport airplanes are certificated to 35,000 feet (old 737s)
    Other older airplanes (707, 727, DC8) are certificated to 42,000 feet...
    The 747 is certificated to 45,100 feet...
    Some Learjet types are certificated to 51,000 feet...
    The Concorde is certificated to 60,000 feet...
    xxx
    For all above airplanes, this is the level at which their cabin will reach 8,000 feet OR limited by the time it would take them to reach 14,000 feet in case of an emergency descent for failure of the pressurization system...
    xxx
    The 747 I fly is legally limited to 45,100 feet, yet, when I was in the Air Force, the E-4 (747 Command Post) was able, in emergency (and when very light in weight) to reach nearly 48,000 to 52,000 feet... at the verge of a stall...
    xxx
    When airplanes are heavy (fuel for very long trip) they are far from able to reach high levels... With my 747, we can barely reach 29,000 feet when we are fully loaded for a trip from Argentina to Europe, yet, at the end of the cruise flights, we occasionally are at 39,000 feet... I hardly ever fly at the maximum certificated of 45,000 feet...
    xxx
    Such a question really belongs to Tech.Ops -  Big grin
    Happy contrails...
    (s) Skipper


    User currently offline727LOVER From United States of America, joined Oct 2001, 6322 posts, RR: 17
    Reply 21, posted (11 years 1 month 1 week 5 days 11 hours ago) and read 31432 times:

    Red N' Gold,

    I believe it was TWA.....N840TW to be exact.



    Listen Betty, don't start up with your 'White Zone' s*** again.
    User currently offlineFutureFO From Ireland, joined Oct 2001, 3132 posts, RR: 21
    Reply 22, posted (11 years 1 month 1 week 5 days 10 hours ago) and read 31357 times:

    I had been on a CO flite to EWR from LAX and we were at FL415 on a 757-200.


    I Don't know where I am anymore
    User currently offlineJmhLUV2fly From United States of America, joined Dec 1999, 559 posts, RR: 0
    Reply 23, posted (11 years 1 month 1 week 5 days 10 hours ago) and read 31336 times:

    From what a AirTran 717 first officer said to me once, my understanding is that for the 717 at least the max altitude that airplane can really go is 35.0 any higher then that and from what he said the wings really are not designed to support the aircraft much above that altitude...
    now most definitly for your 747's and 777's , A340s etc
    they are designed to fly really high 40.0 or so altitude if need be... for max fuel burn etc, I mean keck the trips they commonly serve are 12+ hour flights so it would make sence for them....but not all airplanes can fly that high.
    JMH


    User currently offlineDeltAirlines From United States of America, joined May 1999, 8892 posts, RR: 12
    Reply 24, posted (11 years 1 month 1 week 5 days 10 hours ago) and read 31341 times:

    I've climbed regularly to FL410 on 747, 757, 767, and 777 before.

    I don't think I've gone higher than that on a conventional airliner (read: not Concorde)

    Jeff


    25 ZSSNC : Yikes!, above 36000 feet temperature actually increases up to about 150000 feet where it starts to decrease again. ZSSNC
    26 Yikes! : No, above the tropopause, in a standard atmosphere, temperature remains constant with increase in altitude. When reaching the stratopause, you are the
    27 Yikes! : "Yikes! You are wrong. A DC-8 exceeded Mach 1 in a dive during a test flight. There are also rumours about the VC-10. Mach 1 is not a barrier - thats
    28 Kevi747 : I believe I've been to 45,000 ft in a 767. Is that possible? One time I was hanging out in the cockpit flying from JFK-LAX. I noticed that we had reci
    29 Yikes! : "But Yikes!, Mach is mach period, never 0.90 mach or 1.07 mach. And there are indeed several biz jets certified to fly in the low 50s." Don't understa
    30 FDXmech : >>>Mach 1.0 is a Brick Wall. In fact, it is less than 1.0, usually in the range of .90
    31 FutureFO : The 727 has demonstrated cruise speeds of .91-.95M but be it as a short burst of speed and at a higher altitude to get the performance.
    32 Post contains links Rick767 : Kevi747 "I believe I've been to 45,000 ft in a 767. Is that possible?" Not legally / safely. See below for the max alts. "When airplanes are heavy (fu
    33 IMissPiedmont : Mach 1.0 is a Brick Wall. In fact, it is less than 1.0, usually in the range of .90. I guess I misread what you meant by this Yikes!. I must learn to
    34 Post contains images LSTC : What happens when an airplane goes above 40,000 feet? Everyone gets real high! The 42,000+ foot service ceiling you often see has much to do with cert
    35 FlightSimFreak : I have been to FL 390 in a NW 757 from MSP to PDX... I have proof too.
    36 L-188 : Yeah Mr.Ba I do remember that aircraft, Can't recall if it was a China Air plane or not but it seems right. I belive that it was only shown mathmatica
    37 Post contains images Bellerophon : LSTC Good post, but just one tiny quibble: ...commercial airline cockpits have "demand" type masks... Most do, certainly, but not quite all! Flight cr
    38 LSTC : Bellerophon, That's interesting. Was it a regional requirement to have pressure masks? Could you tell me what kind of things they look for on your anu
    39 777kicksass : Bare in mind that Concorde operated safely at altitudes at up to 64,000feet (i think- correct me if i'm wrong)!! The only health risk is that if you w
    40 Ben : UV rays I doubt UV is much of a problem... dont you mean cosmic radiation?
    41 CitationJet : The Citation X (Model 750) has a maximum operating altitude of 51,000 ft. Also in flight flutter testing to Md of Mach 0.99, they exceeded Mach 1.0 sl
    42 Bellerophon : LSTC It is a UK/French airworthiness certification requirement for the aircraft that pressure breathing apparatus be available for the flight crew. Th
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