Continental 737 Off Runway at DEN
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Good post but I need to correct you on one thing, you attitude indicator in flight will NOT be at near zero in level cruise. Depending on weight, I look at 2.5 to 5 degrees pitch up in level flight at M.86.
Also, even on jets dont forget about Angle Of Incidence. Just about all civilian flying machines have it.
Question??? On the 737, when do you guys get spoiler when deflecting ailerons? We cant use really very much aileron even on a max crosswind takeoff due to the spoiler computer and the large amount of spoilers deflected up on the upwind side. Also, what angle of bank with the 737 catch a pod?
Also, even on jets dont forget about Angle Of Incidence. Just about all civilian flying machines have it.
Question??? On the 737, when do you guys get spoiler when deflecting ailerons? We cant use really very much aileron even on a max crosswind takeoff due to the spoiler computer and the large amount of spoilers deflected up on the upwind side. Also, what angle of bank with the 737 catch a pod?
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FPP
I agree with you. However, misd-agin has appointed himself the speculation (hangar flying) police.
Be careful. The thought police are on the rise. Excessive public hangar flying might get us both expelled.
I agree with you. However, misd-agin has appointed himself the speculation (hangar flying) police.
Be careful. The thought police are on the rise. Excessive public hangar flying might get us both expelled.
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FPP and Cessna120,
I don't think either of you is making that mistaek, but it's remarkable how often people confuse AoA and pitch attitude.
They're most of the time within a few degrees of each other, but there is no one-to-one relation between the two.
CJ
I don't think either of you is making that mistaek, but it's remarkable how often people confuse AoA and pitch attitude.
They're most of the time within a few degrees of each other, but there is no one-to-one relation between the two.
CJ
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Crosswind controls
I do believe that if I am right, that the focus should shift away from the crew and more toward training. The first time that a pilot encounters near crosswind limits on a takeoff shouldn't be with a cabin full of passengers.
If somebody does have the Boeing language, please post it.
Was the 737 problem with uncommanded rudder hardovers ever completely resolved?
If somebody does have the Boeing language, please post it.
Was the 737 problem with uncommanded rudder hardovers ever completely resolved?
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If you do not use enough crosswind controls in high crosswind the plane goes straight until rotation starts. No upwind gear unloading to the point that the airplane weathervanes into the wind. It's ugly, but it shouldn't lead to runway excursions.
There has been no comment by the NTSB that rotation was attempted.
You state if they had continued the takeoff it probably would have been a non-event. In general that's true, but without knowing what occurred in this incident it's way to premature to state that this flight probably would have been a non-event if it had gotten airborne.
Coworker talked about having the rudder jam on him in a 737 doing the flight control check. That would not have been a non-event if they had gotten airborne.
There has been no comment by the NTSB that rotation was attempted.
You state if they had continued the takeoff it probably would have been a non-event. In general that's true, but without knowing what occurred in this incident it's way to premature to state that this flight probably would have been a non-event if it had gotten airborne.
Coworker talked about having the rudder jam on him in a 737 doing the flight control check. That would not have been a non-event if they had gotten airborne.
Last edited by misd-agin; 30th Dec 2008 at 16:15. Reason: rephrasing, grammar
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I'd be very surprised if an experienced crew like this were found to have made such a hash of a simple x/wind T/O . . . . . . . . UNLESS the R/W friction characteristics were way slippier than reported/ expected ,and therefore way out of limits. 
Apart from some mechanical failure of nose gear, brakes or a flight control, I think that is the most plausible reason for departing the paved surface for a bit of rallying for any reasonably experienced crew.
I suppose to that list you could add an uncommanded reverser leaving them with full reverse on the left side and normal take-off thrust on the right, that would make for a fairly rapid departure stage left when combined with a crosswind.
The crux of the matter , which we don't know yet, is whether the T/O was abandoned because of a problem, and control "subsequently" lost because of this problem directly, or a degrading of control because of assymetric braking/reverse thrust. . . . . or whether it was abandoned because of loss of directional control exclusively or as a result of a problem.
Before I tie myself in knots. . . . . did they abandon because they lost control, OR did they lose control because of whatever made them abandon or the effect of this on the stopping phase, or indeed their own inputs.
Duh. . that is clear. . . well maybe?
Apart from some mechanical failure of nose gear, brakes or a flight control, I think that is the most plausible reason for departing the paved surface for a bit of rallying for any reasonably experienced crew.
I suppose to that list you could add an uncommanded reverser leaving them with full reverse on the left side and normal take-off thrust on the right, that would make for a fairly rapid departure stage left when combined with a crosswind.
The crux of the matter , which we don't know yet, is whether the T/O was abandoned because of a problem, and control "subsequently" lost because of this problem directly, or a degrading of control because of assymetric braking/reverse thrust. . . . . or whether it was abandoned because of loss of directional control exclusively or as a result of a problem.
Before I tie myself in knots. . . . . did they abandon because they lost control, OR did they lose control because of whatever made them abandon or the effect of this on the stopping phase, or indeed their own inputs.
Duh. . that is clear. . . well maybe?
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PJ2 and Murexway
According to the limitations section for the 737-500 the max demonstrated cross wind is 35 kts reduced 3 kts with winglets. You may not need this kind of data because your skills may exceed that which was demonstrated by test pilots.
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FPP, apologies for questioning your qualifications.
Still I doubt poor crosswind technique to be the answer (and don't doubt major carrier pilot's skills for that matter).
And for those that believe the nosewheel mechanism is fail-safe read this one:
KLM off the runway at BCN
Turned out to be a birdstrike (falcon?) just after take-off sheering the steering cables and causing an offset nosewheel after landing.
Check out this photo (KLM, not CAL!) of the nosewheel at page 3, feathers still visible.
On page 3 of the BCN thread there is the Boeing point of view. Part of it is relevant for the Denver incident:
Still I doubt poor crosswind technique to be the answer (and don't doubt major carrier pilot's skills for that matter).
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.
KLM off the runway at BCN
Turned out to be a birdstrike (falcon?) just after take-off sheering the steering cables and causing an offset nosewheel after landing.
Check out this photo (KLM, not CAL!) of the nosewheel at page 3, feathers still visible.
On page 3 of the BCN thread there is the Boeing point of view. Part of it is relevant for the Denver incident:
Situations Beyond the Scope of Non-Normal Checklists
"Aggressive differential braking and/or use of asymmetrical reverse thrust, in addition to other control inputs, may be required to maintain directional control."
Boeing believes this general guidance is the only sound instruction and training advice that can be provided to crews to accommodate demanding situations that require the use of various controls to prevent drift and possible runway excursion. These situations include but are not limited to blown tires, collapsed main landing gear, strong crosswinds on dry runways, thrust reverser anomalies, icy patches on runways, seized brakes and nose wheel steering anomalies including jammed steering metering valves and the kind associated with the subject accident.
R. S. Breuhaus, Chief Engineer, Air Safety Investigation BOEING
"Aggressive differential braking and/or use of asymmetrical reverse thrust, in addition to other control inputs, may be required to maintain directional control."
Boeing believes this general guidance is the only sound instruction and training advice that can be provided to crews to accommodate demanding situations that require the use of various controls to prevent drift and possible runway excursion. These situations include but are not limited to blown tires, collapsed main landing gear, strong crosswinds on dry runways, thrust reverser anomalies, icy patches on runways, seized brakes and nose wheel steering anomalies including jammed steering metering valves and the kind associated with the subject accident.
R. S. Breuhaus, Chief Engineer, Air Safety Investigation BOEING
Last edited by golfyankeesierra; 30th Dec 2008 at 21:09.
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beechf33a:
Well from what I gather about your airline experience, I simply can't imagine your presumptuousness in questioning the comments or experience of the "real" airline pilots who post in this forum.
Unlike you evidently, I have flown for 15 years as Captain for a major air carrier - without ever putting so much as a scratch on a passenger or an airplane. This is winter and summer, day and night, in all kinds of weather. I've never exceeded any limitations in the flight manual (which for my aircraft is a 30kt crosswind component (50kts total wind) on a dry runway with good visibility and all aircraft systems operational - ie. no placards on relevant equipment. I have made hundreds and hundreds of takeoffs and landings in weather that you probably wouldn't even be driving your car in - and that includes both takeoffs and landings at the max crosswind limit for the weather.
But none of this is exceptional or out of the ordinary. Every airline pilot (Captain and F/O alike) who posts on this forum has done, and is doing, the same things every day of the week - which is exactly what you're paid, and expected, to do when you're a real airline pilot.
PJ2 and Murexway.....
"According to the limitations section for the 737-500 the max demonstrated cross wind is 35 kts reduced 3 kts with winglets. You may not need this kind of data because your skills may exceed that which was demonstrated by test pilots."
"According to the limitations section for the 737-500 the max demonstrated cross wind is 35 kts reduced 3 kts with winglets. You may not need this kind of data because your skills may exceed that which was demonstrated by test pilots."
Unlike you evidently, I have flown for 15 years as Captain for a major air carrier - without ever putting so much as a scratch on a passenger or an airplane. This is winter and summer, day and night, in all kinds of weather. I've never exceeded any limitations in the flight manual (which for my aircraft is a 30kt crosswind component (50kts total wind) on a dry runway with good visibility and all aircraft systems operational - ie. no placards on relevant equipment. I have made hundreds and hundreds of takeoffs and landings in weather that you probably wouldn't even be driving your car in - and that includes both takeoffs and landings at the max crosswind limit for the weather.
But none of this is exceptional or out of the ordinary. Every airline pilot (Captain and F/O alike) who posts on this forum has done, and is doing, the same things every day of the week - which is exactly what you're paid, and expected, to do when you're a real airline pilot.
Last edited by Murexway; 31st Dec 2008 at 00:00.
beechf33a;
You said,
Sarcasm is a form of personal disrespect which is inappropriate in a professional discussion. When you are able to engage the dialogue on a civil level, we can continue. Did you really think I was bragging?...
You said,
You may not need this kind of data because your skills may exceed that which was demonstrated by test pilots.
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737 NG crosswind numbers
"Crosswind Takeoff
There is good crosswind control capability during takeoff. Initial rwy alignment and smooth symmetrical thrust application are important. Directional deviations should be corrected immediately with smooth and positive control inputs.
Note: Engine surge can occur with a strong crosswind compontent if t/o thrust is set prior to brake release. Therefore, the rolling t/o procedure is strongly advised when crosswind exceeds 20 knots.
Takeoff Crosswind Guidelines
Crosswind guidelines are not considered limitations. Crosswind guidelines are provided to assist operators in establishing theri own crosswind policies.
T/O crosswind guidelines are based upon the most adverse airplane loading (lightweight and aft center of gravity) and assume an engine out RTO. On slippery runways, crosswind guidelines are a function of rwy surface condition, and assume proper pilot technique.
RWY Condition Crosswind-knots*
-600 -700 w/o winglets -800/900 w/o winglets
DRY 36kts 36/34 36/34
WET 20 23/21 27/25
Standing Water/Slu 14 16 19
Snow-not melting** 18 21/19 26/24
ICE-not melting** 7 7 8
* Winds measured at 33 ft (10m) tower height and apply for rwy 148 ft (45m) or greater in width.
**T/O on untreated ice or snow should only be attempted when no melting is present.
Any tendencey to deviate from the centerline during thrust application should be counted with immediate and smooth and positive rudder input. During wet and slippery rwy conditions, the PNF should give special attention to assuring the engines have symmetrically balanced thrust indications.
Light forward pressure on the control column during the initial phase of t/o roll (below 80 kts) increases nose wheel steering effectiveness. Above 80 kts, relax the forward control ccolumn pressure to the neutral position."
Regards,
jack
There is good crosswind control capability during takeoff. Initial rwy alignment and smooth symmetrical thrust application are important. Directional deviations should be corrected immediately with smooth and positive control inputs.
Note: Engine surge can occur with a strong crosswind compontent if t/o thrust is set prior to brake release. Therefore, the rolling t/o procedure is strongly advised when crosswind exceeds 20 knots.
Takeoff Crosswind Guidelines
Crosswind guidelines are not considered limitations. Crosswind guidelines are provided to assist operators in establishing theri own crosswind policies.
T/O crosswind guidelines are based upon the most adverse airplane loading (lightweight and aft center of gravity) and assume an engine out RTO. On slippery runways, crosswind guidelines are a function of rwy surface condition, and assume proper pilot technique.
RWY Condition Crosswind-knots*
-600 -700 w/o winglets -800/900 w/o winglets
DRY 36kts 36/34 36/34
WET 20 23/21 27/25
Standing Water/Slu 14 16 19
Snow-not melting** 18 21/19 26/24
ICE-not melting** 7 7 8
* Winds measured at 33 ft (10m) tower height and apply for rwy 148 ft (45m) or greater in width.
**T/O on untreated ice or snow should only be attempted when no melting is present.
Any tendencey to deviate from the centerline during thrust application should be counted with immediate and smooth and positive rudder input. During wet and slippery rwy conditions, the PNF should give special attention to assuring the engines have symmetrically balanced thrust indications.
Light forward pressure on the control column during the initial phase of t/o roll (below 80 kts) increases nose wheel steering effectiveness. Above 80 kts, relax the forward control ccolumn pressure to the neutral position."
Regards,
jack
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PJ2:
Murexway:
I apologize if I have offended you or any others on this forum. This discussion was initiated when I ask a simple question. What did the Boeing Manual say about a cross wind take off? With my regards and respect.
Murexway:
I apologize if I have offended you or any others on this forum. This discussion was initiated when I ask a simple question. What did the Boeing Manual say about a cross wind take off? With my regards and respect.
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That hardover problem
Just so I can clarify, as a humble SLF - that 737 uncommanded hardover issue was never properly solved, was it? My understanding is that there are just a bunch of workarounds? Or are newer models fitted with extra bits to stop the problem happening?
beechf33a;
No offence! I can assure you that all that time in all those airplanes did not guarantee "no surprises" and "no days without a lesson"...I never came home without something in my back pocket...so to speak.
It is of great (and increasing) interest to see how this unfolds. I think the crosswind notion has been beaten up pretty good so we'll see how it all washes.
No offence! I can assure you that all that time in all those airplanes did not guarantee "no surprises" and "no days without a lesson"...I never came home without something in my back pocket...so to speak.
It is of great (and increasing) interest to see how this unfolds. I think the crosswind notion has been beaten up pretty good so we'll see how it all washes.
Last edited by PJ2; 31st Dec 2008 at 00:20.
overthewing;
I googled "737 rudder solution" and the website to which the link below is provided came up among many and is I think, one you'll find really helpful. I will leave it to the 73' drivers to respond to your question on whether the problem is "fixed" or "worked around" - I suspect a little of the latter and a lot of the former, but I haven't trained on/flown the airplane. Here's the link.
I googled "737 rudder solution" and the website to which the link below is provided came up among many and is I think, one you'll find really helpful. I will leave it to the 73' drivers to respond to your question on whether the problem is "fixed" or "worked around" - I suspect a little of the latter and a lot of the former, but I haven't trained on/flown the airplane. Here's the link.
Last edited by PJ2; 31st Dec 2008 at 00:19.
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.. united 585 USair 427 crashes..
Both the United 585 and USair 427 rudder hard over 737 crashes were attributed eventually to a fault in the 737's rudder dual servo valve. In that it could not only jam without warning in flight causing huge yaw and so roll in the direction of the jam, but also that the valve cold actually reverse. So that when applying a right rudder input to try correct the problem, your would actually be applying left rudder and so without knowing stearing the plane further into trouble. I know now that go arounds for rudder hard over/ reversals are now trained for in simulator training. Boeing had said that by November this year I think they would have replaced all the boeing 737's in service rudder control unit, to eliminate the potential for this happening. I hope that is of some help.
Chris.
Chris.
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beechf33a:
PJ2:
Murexway:
I apologize if I have offended you or any others on this forum. This discussion was initiated when I ask a simple question. What did the Boeing Manual say about a cross wind take off? With my regards and respect.
PJ2:
Murexway:
I apologize if I have offended you or any others on this forum. This discussion was initiated when I ask a simple question. What did the Boeing Manual say about a cross wind take off? With my regards and respect.
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Many thanks, PJ2 and X13CDX. Does this suggest that it's unlikely that the CAL excursion might be down to rudder malfunction? I'm only familiar with hardover incidents that happened in flight, but is there any technical reason why they wouldn't happen during takeoff (assuming no fix has been applied to the a/c)?
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.. after reading the initial news reports, especially the quotes taken from the first officer.. I had thought about whether the sudden veering of the jet off to the left could have been from a rudder incident such as this.. as obviously direction of movement down the center of the runway is depicted by the use of the rudder.. although i am not sure about how likely this could be the cause, for all of two reasons.. one being that all rudder components with the potential for this to happen should have now been retro fitted.. and two, the problems with the 2 fatal rudder hard over incidents and the one that managed to recover and land, happened in flight on approach into their destination airport.. after lots of testing of the dual servo valve it was found that when exposed to the extreme cold temperatures in flight.. an imput of hot hydraulic fluid that would operate the valve when commanded, could cause the components to rapidly expand and so jam.. im not sure if there are many other situations in where the rudder can jam uncommanded in this same way but with this aircraft at ground level, even with the extremes of winter temperatures, it wouldnt be cold enough to simulate temperatures experienced when at high altitudes.. and so i would have thought unlikely..
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It was reported in AvWeek, in June of '91 or '92 (before US 427,) that a UAL 737-300 had rudder control reversal on taxi out at KSFO. They returned to gate.
There was also "The Mysterious Crash of Flight 201" a Public Broadcasting System (US) documentary, about a COPA 737-200 that went out of control at night over Panama jungle in about 1991. The blame was largely given to the vertical gyro, but it appeared to me the rudder was just as likely.
The final fix for new planes in the 737 series was CAT IIIb autoland system, which, oh by the way, requires a Fail Active rudder. In other words, a full redesign to reduce the probability of a hardover to maybe 10 to -7.
Please ignore this that I wrote originally: (Intermittent rudder hardover in this case would likely have shown up more as sideways shaking than the noises they heard.)
I have no knowledge of how a wayward rudder would sound on the CVR, and I would be surprised if it turned out to be a rudder malfunction in this case.
GB
There was also "The Mysterious Crash of Flight 201" a Public Broadcasting System (US) documentary, about a COPA 737-200 that went out of control at night over Panama jungle in about 1991. The blame was largely given to the vertical gyro, but it appeared to me the rudder was just as likely.
The final fix for new planes in the 737 series was CAT IIIb autoland system, which, oh by the way, requires a Fail Active rudder. In other words, a full redesign to reduce the probability of a hardover to maybe 10 to -7.
Please ignore this that I wrote originally: (Intermittent rudder hardover in this case would likely have shown up more as sideways shaking than the noises they heard.)
I have no knowledge of how a wayward rudder would sound on the CVR, and I would be surprised if it turned out to be a rudder malfunction in this case.
GB
Last edited by Graybeard; 31st Dec 2008 at 04:38. Reason: Clarification