Continental 737 Off Runway at DEN
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Quote:
Originally Posted by golfyankeesierra"
FPP, are you a pilot?
Are you?
Judging by your remarks you're not....
Originally Posted by golfyankeesierra"
FPP, are you a pilot?
Are you?
Judging by your remarks you're not....
In their FCOM's both Boeing and Airbus stress the importance of correct rotation. If you rotate too early you get a tailstrike or it won't fly at all, if you rotate too late it flies to late.
It's all about AoA, airliners don't fly just by rolling down a runway.
The reason I react is that PFF connects this incident with poor crosswind technique:
this seems like a good opportunity to look at good crosswind technique, which I have found sorely lacking in many pilots that I've flown with.
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The Messenger -
Sorry about being slow to respond, I was actually flying planes for a living instead of speculating about issues that some folks seem to have limited understanding of. And, as you can see, others have already questioned FPP's excellent
speculations.
I'm glad you liked FPP's "assumptions, speculations, and theories". Using all the 'large' jet time you have could you tell me what effect you think too much, too little, or no crosswind controls, would have on your jet?
Hey, I agree with FPP that it's not surprising to see less than good or excellent crosswind techniques. But that even gets debated as to what's the correct technique.
But, using all you airliner type experience, what impact would that technique have on the a/c that would lead you to think it would cause the airplane to depart the runway like the CAL a/c did?
Sorry about being slow to respond, I was actually flying planes for a living instead of speculating about issues that some folks seem to have limited understanding of. And, as you can see, others have already questioned FPP's excellent
speculations.I'm glad you liked FPP's "assumptions, speculations, and theories". Using all the 'large' jet time you have could you tell me what effect you think too much, too little, or no crosswind controls, would have on your jet?
Hey, I agree with FPP that it's not surprising to see less than good or excellent crosswind techniques. But that even gets debated as to what's the correct technique.
But, using all you airliner type experience, what impact would that technique have on the a/c that would lead you to think it would cause the airplane to depart the runway like the CAL a/c did?
misd-agin;
I think it would take significant abuse of the flight controls and nosewheel steering to cause an airliner to depart the runway in a crosswind.
In other words, if the pilot flying is handling the controls appropriately with regard to a strong crosswind the aircraft would not "depart the runway on it's own" in a 25kt (or so) crosswind and if the pilot flying did nothing until the airplane itself signalled that it needed help in staying straight, recovery would not be an issue and would not, in and of itself, take the airplane off the runway. Neutral controls in a certified/demonstrated crosswind does not, I think, constitute "significant abuse" of the controls but rudder into wind might, as might full aileron into wind, depending upon runway friction index. Clearly, aileron turned towards the downwind side would be abuse.
The proof, for me, of this statement is not only in the data I examine every day and the previous 35 years flying the DC9, DC8, B727, B767, L1011, A319/320, A330/340 in RHS & LHS in Canadian winters including St. John's Nlfd
, but "out there", in the accident rate around the world in which crosswinds were a causal and not merely contributing factor - ie., there just aren't any such accidents even as there are some very spectacular landings and near-accidents in very high, (beyond "demonstrated", as at Hamburg). crosswinds. Keep in mind too, the many statements made here by other professional colleagues - that CAL crews are not low-time, start-up, inexperienced, (MPL'd!) airmen but are seasoned veterans who meet such operational challenges as a matter of course just like high-time, professional crews do all over the world. Like others who teach, in training/line indoc work I've seen some interesting approaches and very "interesting" touchdowns and takeoffs, none of which resulted in anything more than a seatcover-change and discussion.
Airplanes just don't depart runways in a 25kt crosswind without significantly altered circumstances or untoward mechanical failure.
All this said, on a slippery runway, (very low JBI or CRFI readings), crosswind limitations MUST be respected, not because the airplane will "automatically" be blown off the runway, for, unless the JBI/CRFI is near zero, certified crosswind limits and reductions of same using the CRFI charts are generally not a problem on sanded/urea-treated runways,... but because the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.
All of this is (or should be) standard knowledge in a professional airman's toolkit, especially those who fly transport category aircraft and at the very least should be part of any airline or corporate initial and recurrent training syllabus.
PJ2
But, using all you airliner type experience, what impact would that technique have on the a/c that would lead you to think it would cause the airplane to depart the runway like the CAL a/c did?
In other words, if the pilot flying is handling the controls appropriately with regard to a strong crosswind the aircraft would not "depart the runway on it's own" in a 25kt (or so) crosswind and if the pilot flying did nothing until the airplane itself signalled that it needed help in staying straight, recovery would not be an issue and would not, in and of itself, take the airplane off the runway. Neutral controls in a certified/demonstrated crosswind does not, I think, constitute "significant abuse" of the controls but rudder into wind might, as might full aileron into wind, depending upon runway friction index. Clearly, aileron turned towards the downwind side would be abuse.
The proof, for me, of this statement is not only in the data I examine every day and the previous 35 years flying the DC9, DC8, B727, B767, L1011, A319/320, A330/340 in RHS & LHS in Canadian winters including St. John's Nlfd
, but "out there", in the accident rate around the world in which crosswinds were a causal and not merely contributing factor - ie., there just aren't any such accidents even as there are some very spectacular landings and near-accidents in very high, (beyond "demonstrated", as at Hamburg). crosswinds. Keep in mind too, the many statements made here by other professional colleagues - that CAL crews are not low-time, start-up, inexperienced, (MPL'd!) airmen but are seasoned veterans who meet such operational challenges as a matter of course just like high-time, professional crews do all over the world. Like others who teach, in training/line indoc work I've seen some interesting approaches and very "interesting" touchdowns and takeoffs, none of which resulted in anything more than a seatcover-change and discussion. Airplanes just don't depart runways in a 25kt crosswind without significantly altered circumstances or untoward mechanical failure.
All this said, on a slippery runway, (very low JBI or CRFI readings), crosswind limitations MUST be respected, not because the airplane will "automatically" be blown off the runway, for, unless the JBI/CRFI is near zero, certified crosswind limits and reductions of same using the CRFI charts are generally not a problem on sanded/urea-treated runways,... but because the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.
All of this is (or should be) standard knowledge in a professional airman's toolkit, especially those who fly transport category aircraft and at the very least should be part of any airline or corporate initial and recurrent training syllabus.
PJ2
Last edited by PJ2; 29th Dec 2008 at 21:06.
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PJ2 -
I was trying to get The Messenger to reply. He's a fan of FPP's speculation and apparently an 'expert' of some type.
I'd almost completely agree with your post except that human error sometimes does creep into accidents in unexpected ways. Not saying that did happen, but until we understand what did occur I'd rather leave the speculationing to the 'experts'.
I was trying to get The Messenger to reply. He's a fan of FPP's speculation and apparently an 'expert' of some type.
I'd almost completely agree with your post except that human error sometimes does creep into accidents in unexpected ways. Not saying that did happen, but until we understand what did occur I'd rather leave the speculationing to the 'experts'.
beechf33a;
I think, first of all, the question is addressed in the thread.
That said, you must have in mind a "satisfactory" answer which would be compared to the actual weather conditions at the time. That has been done also.
Other than this, where would this line of enquiry take you such that new information is obtained? Is there something missing in the discussion point above that doesn't apply to the 737 or crosswind ops in general? I am certainly open to such points but don't see the point of this particular question.
With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off.
That said, you must have in mind a "satisfactory" answer which would be compared to the actual weather conditions at the time. That has been done also.
Other than this, where would this line of enquiry take you such that new information is obtained? Is there something missing in the discussion point above that doesn't apply to the 737 or crosswind ops in general? I am certainly open to such points but don't see the point of this particular question.
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beechf33a:
"With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off. Let us know 737 pilots."
--------------------------------------------------
This isn't a training forum.
If you're so curious about flying techniques and limitations in transport catagory aircraft, I have a suggestion for you:
There are ads at the top of the forum pages for training outfits offering 737 type-ratings. Why not sign up for a course and get qualified in the 737.............. then you'll know.
"With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off. Let us know 737 pilots."
--------------------------------------------------
This isn't a training forum.
If you're so curious about flying techniques and limitations in transport catagory aircraft, I have a suggestion for you:
There are ads at the top of the forum pages for training outfits offering 737 type-ratings. Why not sign up for a course and get qualified in the 737.............. then you'll know.
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I think it would take significant abuse of the flight controls and nosewheel steering to cause an airliner to depart the runway in a crosswind.
One for the TRIs and SFIs out there. If you are in a sim that has dual tillers (or are doing a command course for a first time captain), and can shoehorn a spare 5 mins out of the session, try this one:
Introduce a medium crosswind (e.g. 15-20kts or so) and a heavy configuration, then get them to take off with use of the nosewheel tiller only, feet flat on the floor. On my very first sim session ever, we lucky enough to get a few free minutes and the SFI got me to do this, he then sat back and enjoyed the PIO from his station. His point in the extercise had been to illustrate the risks of being over judicious with the tiller in the case of having directional control problems.
I personally do not think that PIO played a part in this in any way, however this is a good exercise to try never the less.
the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.
On the subject of roll spoiler, this is basic training stuff. I can't believe a Continental pilot would fall foul of being ignorant of this.
On reversers. It is possible for the reversers to contribute their element of the retarding force in such a manner as to be pro crosswind. Once you have then started pointing towards the upwind side of the runway, your only recourse is to dump the reversers. Again, one that is better to learn about in the sim.
With all the discussion about cross wind, I wonder what the Boeing 737-500 manual says about a cross wind take off. Let us know 737 pilots.
If you are just an interested observer go to b737.org.uk.
RIX
Last edited by Romeo India Xray; 30th Dec 2008 at 02:19. Reason: Too much vin rouge last night
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Quote:
the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.
Quite right.
On the subject of roll spoiler, this is basic training stuff. I can't believe a Continental pilot would fall foul of being ignorant of this.
On reversers. It is possible for the reversers to contribute their element of the retarding force in such a manner as to be pro crosswind. Once you have then started pointing towards the upwind side of the runway, your only recourse is to dump the reversers. Again, one that is better to learn about in the sim.
********************************************************
The statements about the plane weather vaning into the wind, eg. when using reverse thrust, are with reduced traction.
Crosswinds, full reverser, traction better than 'slick', and the plane tracks straight.
the moment significant roll-spoiler is introduced with big aileron displacements into wind, or, in a rejected takeoff, reverse is brought to high power settings, the airplane WILL be turned into wind or will otherwise drift downwind according to and as a result of the thrust, crosswind, drag and wheel-friction vectors.
Quite right.
On the subject of roll spoiler, this is basic training stuff. I can't believe a Continental pilot would fall foul of being ignorant of this.
On reversers. It is possible for the reversers to contribute their element of the retarding force in such a manner as to be pro crosswind. Once you have then started pointing towards the upwind side of the runway, your only recourse is to dump the reversers. Again, one that is better to learn about in the sim.
********************************************************
The statements about the plane weather vaning into the wind, eg. when using reverse thrust, are with reduced traction.
Crosswinds, full reverser, traction better than 'slick', and the plane tracks straight.
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The statements about the plane weather vaning into the wind, eg. when using reverse thrust, are with reduced traction.
I really did have too much of the red last night
RIX
misd-agin;
Yes, exactly - thank you for emphasizing this point. The airplane will indeed track straight quite nicely on a dry, uncontaminated runway in these circumstances, (high crosswind, rejected takeoff).
The "CRFI" is the "Canadian Runway Friction Index" and, as indicated in my post, are to be taken into account when dealing with contaminated runways and crosswinds. The CRFI may actually be making it's way to US operations as a result of the Southwest Midway accident. It is well worth examining just for the information it can provide. I'm sure it's familiar in one form or another to crews.
No, not at all, so fully agree with your comment - this is all basic stuff, well within both airplane and experienced crew's capabilities.
RIX;
Yes, but 'tis the Season! Happy New Year in Riga!
The statements about the plane weather vaning into the wind, eg. when using reverse thrust, are with reduced traction.
Crosswinds, full reverser, traction better than 'slick', and the plane tracks straight.
Crosswinds, full reverser, traction better than 'slick', and the plane tracks straight.
The "CRFI" is the "Canadian Runway Friction Index" and, as indicated in my post, are to be taken into account when dealing with contaminated runways and crosswinds. The CRFI may actually be making it's way to US operations as a result of the Southwest Midway accident. It is well worth examining just for the information it can provide. I'm sure it's familiar in one form or another to crews.
I can't believe a Continental pilot would fall foul of being ignorant of this.
RIX;
I really did have too much of the red last night
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Yes, but 'tis the Season! Happy New Year in Riga!
) Happy New Year in your neck of the woods too!
Yes, exactly - thank you for emphasizing this point. The airplane will indeed track straight quite nicely on a dry, uncontaminated runway in these circumstances, (high crosswind, rejected takeoff).
RIX
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Control Inputs Probably Inefective
This discussion needs an injection of new facts that will come from a look at the nose gear. Possibly a failure mode that would negate anything the crew could do with the controls to keep it on the runway.
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The above scenario seems unlikely as the 737, like most other mechanically controlled nosewheel aircraft, uses geometry that keeps the nosewheel pointing straight ahead whether linkage is connected or not.
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Crosswind controls
Sorry, I was away for a while. I'll paraphrase and answer some questions:
Yes, I am a pilot. 20 years with major airline, 2 of those sitting sideways, and 7 years military (including jet instructor pilot) before that. I have zero hours on the 737, but type ratings and many hours in 727, 757, 767, and MD80 (DC9 type).
Yes, a wing produces lift even with zero degrees pitch attitude. Just take a look at your attitude indicator during cruise flight, it will be close to zero by design. Add flaps, which increase the angle of chord, and slats, which decrease the angle of chord in the wing cross section, and you are still producing lift. Only a symmetrical cross section wing will produce no lift at zero angle of attack (angle between wing chord and relative wind). I know that this is not an educational forum, but since there are misconceptions among those giving opinions here, it seemed relevant.
Is there enough lift in a maximum crosswind situation close to Vr to raise the upwind wing with zero pitch and neutral aileron? Certainly if the rotation had started, but what if it hasn't? This is what I see as the crux of the debate here.
Is it relevant to the discussion to know what Boeing prints in its flight manuals about crosswind takeoffs and when to apply aileron? Of course it is.
Of all of the crosswind takeoffs on youtube, how many of them aborted at high speed? If Continental had continued its takeoff, this likely would have been a non-event.
How many takeoffs have you made at your crosswind limits? I can't imagine that it's very many. And how many of these have you aborted at high speed?
My speculation has no bearing on the the true cause. The flight data recorder has recorded all of the relevant parameters and information be released when the authorities have hashed it out between Boeing, the government, Continental and ALPA. Don't be surprised if you see your next recurrent sim profile include a max crosswind takeoff.
You have no idea how much I am hoping that I am wrong, and that equipment failure (nosewheel or something else) or inaccurate wind reporting is found to be the true cause. I, too, hate when the media automatically believe that pilots are at fault. But, you have to ask yourself, why do we even have these "hangar flying" discussions? Why investigate accidents? Hopefully, it is to improve the safety of flying for everybody.
Yes, I am a pilot. 20 years with major airline, 2 of those sitting sideways, and 7 years military (including jet instructor pilot) before that. I have zero hours on the 737, but type ratings and many hours in 727, 757, 767, and MD80 (DC9 type).
Yes, a wing produces lift even with zero degrees pitch attitude. Just take a look at your attitude indicator during cruise flight, it will be close to zero by design. Add flaps, which increase the angle of chord, and slats, which decrease the angle of chord in the wing cross section, and you are still producing lift. Only a symmetrical cross section wing will produce no lift at zero angle of attack (angle between wing chord and relative wind). I know that this is not an educational forum, but since there are misconceptions among those giving opinions here, it seemed relevant.
Is there enough lift in a maximum crosswind situation close to Vr to raise the upwind wing with zero pitch and neutral aileron? Certainly if the rotation had started, but what if it hasn't? This is what I see as the crux of the debate here.
Is it relevant to the discussion to know what Boeing prints in its flight manuals about crosswind takeoffs and when to apply aileron? Of course it is.
Of all of the crosswind takeoffs on youtube, how many of them aborted at high speed? If Continental had continued its takeoff, this likely would have been a non-event.
How many takeoffs have you made at your crosswind limits? I can't imagine that it's very many. And how many of these have you aborted at high speed?
My speculation has no bearing on the the true cause. The flight data recorder has recorded all of the relevant parameters and information be released when the authorities have hashed it out between Boeing, the government, Continental and ALPA. Don't be surprised if you see your next recurrent sim profile include a max crosswind takeoff.
You have no idea how much I am hoping that I am wrong, and that equipment failure (nosewheel or something else) or inaccurate wind reporting is found to be the true cause. I, too, hate when the media automatically believe that pilots are at fault. But, you have to ask yourself, why do we even have these "hangar flying" discussions? Why investigate accidents? Hopefully, it is to improve the safety of flying for everybody.