Continental 737 Off Runway at DEN
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Bizjets like the Global Express, and regional airliners have 28 VDC generators on the engines and APU, and use inverters for AC requirements. You then see why the recorders are on the DC bus in those planes.
It was conjectured that the rudder trim may have been displaced by the jumpseat rider's foot or perhaps a meal tray set on the pedestal to serve coffee
Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.
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Tires
The NTSB briefing in my opinion all but ruled out tires as a root cause. Only one main wheel tire was blown (right side inner wheel) and Mr Sumwalt explained that the track marks indicated it was OK until late in the event when the plane got its other damage. No mention of treads ripping off either; NTSB said there was no debris on the runway and the damage to the wheel was described more like "a gash".
Nosewheel is under the fuselage so not examined yet. But I'd think that if it had been wobbling due to shimmy, it would have left oscillating marks on the runway. No mention about that either; Mr Sumwalt said NTSB has found nosewheel track marks on the runway but that was somewhat beyond the point where main wheels started to "leave rubber on the runway".
The FDR information together with detailed wind data becomes more and more interesting.
Nosewheel is under the fuselage so not examined yet. But I'd think that if it had been wobbling due to shimmy, it would have left oscillating marks on the runway. No mention about that either; Mr Sumwalt said NTSB has found nosewheel track marks on the runway but that was somewhat beyond the point where main wheels started to "leave rubber on the runway".
The FDR information together with detailed wind data becomes more and more interesting.
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Runaway rudder trim
Don't think rudder trim has anything to do with this incident, but they do happen!
Collegue of mine had it during flight. Since the 73's are all bent and it's common to use the rudder trim with A/P on to center the controlwheel (to avoid spoilerdeflection), he was using the trim a little bit. Before he knew he was flying crosscontrolled with a fully deflected trim. Turned out to be a sticky residue of coffee or something in the switches.
Maybe so but I experienced a rudder trim runaway in the B737-300 simulator. If you tweaked the knob and let it go (as you would), the damned trim slowly ran to full deflection. During that session the instructor was constantly criticising my handling of engine failure after take off as I was having considerable difficulty in keeping wheel central and applying correct amount of rudder. Later we discovered that each time I touched the rudder trim after it had been centralised at my request by the PNF the aircraft started to rock and roll. This was due to the rudder trim going uncommanded full scale.
Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.
Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.
Trash du Blanc
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ALPA hid the crew in a local hotel for two days before they would allow the feds to interview and do drug tests.
It was also surrounded by the city's SWAT team at one point. The district attorney was up for election I believe....
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Belgique, please watch the videos, you are speculating about things that have already been ruled out in public by the NTSB during their news conference on monday i.e. two failed tires on one side.
The NTSB also said that the tire marks left on the runway indicate that all the tires were fully inflated until after the initial event, although one tire has a gash in it, this is thought to have happened during the distance travelled off the runway. However, they still didnt rule it out 100% as a cause.
Snowfalcon2, i would be more concerned if the nose gear rubber marks on the runway started in the same place as the main gear, to me (not an expert) a 100 feet gap between nose and main gear marks seems about right on an aircraft of this length.
another quote from the video:
"One of the things we would typically look for was how was the airplane configured for take off, and we were able to determine that the flaps, the slats, the speed brake and the trim were all in a position consistent with a normal takeoff. The flaps were set at 5 degrees, the slats were set at normal take off associated with 5 degrees of flaps, the speed brake was down and the trim (the stabaliser trim) was set at a takeoff that we would normally expect to see for takeoff.
The tires, certainly there is a lot of questions out there about the tires and brakes, and we found absolutely no flat spots on any of the four main landing gear. Bear in mind we still dont have access to the nose gear because its tucked under the fuselage right now. No flat spots on the main landing gear tires and with the exception of one of the tires (which I'll talk about in just a moment) all of the 3 main landing gear tires were inflated to the normal inflation pressure. The one that was an exception to that was what I'll call the number 3 tire, thats on the right hand landing gear, the inboard tire. That tire did have a slash in it, but i want to point out the physical evidence of the tire marks that we've seen indicate that at the time that the air plane departed the runway and as it started through the (I'm calling it grass, its really ice i guess these days) but as the air plane was going through this grassy area and going over taxiway whisky charlie the physical evidence form the tire marks indicates that all 4 main landing gear were inflated at the time that the airplane was going off the runway and going through this grassy area. Our prelimiinary thoughts would be that this deflation occured during the impact sequence. We will do further study of that.
Now the brakes, the brake manifolds showed no leaks, they showed no locked brakes (no evidence of locked brakes). The brake stack (which would be the brake pads) the brake stacks looked good and the brake wear pins (which would give you an indicaton of how much the brakes have worn) the brake wear pins looked good and in the eyes of the NTSBs systems groups chairman he said there appears to be alot of life left in these brakes. so there is no indications from the physical examinations on scene of any brake problems, at this time.
the power plants (the engines) the on scene examination of the engines and the information of the flight data recorder contains no information, no evidence, to leads us to believe that there was any pre-impact problems associated with either of the two engines."
videos again:
part1: 9NEWS.com | Colorado's Online News Leader | Video
part2: 9NEWS.com | Colorado's Online News Leader | Video
part3: 9NEWS.com | Colorado's Online News Leader | Video
The NTSB also said that the tire marks left on the runway indicate that all the tires were fully inflated until after the initial event, although one tire has a gash in it, this is thought to have happened during the distance travelled off the runway. However, they still didnt rule it out 100% as a cause.
Snowfalcon2, i would be more concerned if the nose gear rubber marks on the runway started in the same place as the main gear, to me (not an expert) a 100 feet gap between nose and main gear marks seems about right on an aircraft of this length.
another quote from the video:
"One of the things we would typically look for was how was the airplane configured for take off, and we were able to determine that the flaps, the slats, the speed brake and the trim were all in a position consistent with a normal takeoff. The flaps were set at 5 degrees, the slats were set at normal take off associated with 5 degrees of flaps, the speed brake was down and the trim (the stabaliser trim) was set at a takeoff that we would normally expect to see for takeoff.
The tires, certainly there is a lot of questions out there about the tires and brakes, and we found absolutely no flat spots on any of the four main landing gear. Bear in mind we still dont have access to the nose gear because its tucked under the fuselage right now. No flat spots on the main landing gear tires and with the exception of one of the tires (which I'll talk about in just a moment) all of the 3 main landing gear tires were inflated to the normal inflation pressure. The one that was an exception to that was what I'll call the number 3 tire, thats on the right hand landing gear, the inboard tire. That tire did have a slash in it, but i want to point out the physical evidence of the tire marks that we've seen indicate that at the time that the air plane departed the runway and as it started through the (I'm calling it grass, its really ice i guess these days) but as the air plane was going through this grassy area and going over taxiway whisky charlie the physical evidence form the tire marks indicates that all 4 main landing gear were inflated at the time that the airplane was going off the runway and going through this grassy area. Our prelimiinary thoughts would be that this deflation occured during the impact sequence. We will do further study of that.
Now the brakes, the brake manifolds showed no leaks, they showed no locked brakes (no evidence of locked brakes). The brake stack (which would be the brake pads) the brake stacks looked good and the brake wear pins (which would give you an indicaton of how much the brakes have worn) the brake wear pins looked good and in the eyes of the NTSBs systems groups chairman he said there appears to be alot of life left in these brakes. so there is no indications from the physical examinations on scene of any brake problems, at this time.
the power plants (the engines) the on scene examination of the engines and the information of the flight data recorder contains no information, no evidence, to leads us to believe that there was any pre-impact problems associated with either of the two engines."
videos again:
part1: 9NEWS.com | Colorado's Online News Leader | Video
part2: 9NEWS.com | Colorado's Online News Leader | Video
part3: 9NEWS.com | Colorado's Online News Leader | Video
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It was a hospital, as I recall.
From the NTSB report:
The Safety Board is extremely concerned that no federal investigators were allow to speak to the pilots of flight 5050 until almost 40 hours after the accident. Specific requests to USAir and ALPA to interview the pilots and to have them provide toxicological samples were made about ten hours and again about 20 hours after the accident. USAir representatives stated they did not know where the pilots were sequestered.
The Air Line Pilots Association representatives initially stated that they also did not know where the pilots were, then later stated that their location was being withheld so they could not be found by the media. This complicated the investigative process to a great degree. The sequestering of the pilots for such an extended period of time in many respects borders on interference with a federal investigation and is inexcusable.
The Air Line Pilots Association representatives initially stated that they also did not know where the pilots were, then later stated that their location was being withheld so they could not be found by the media. This complicated the investigative process to a great degree. The sequestering of the pilots for such an extended period of time in many respects borders on interference with a federal investigation and is inexcusable.
It was also surrounded by the city's SWAT team at one point. The district attorney was up for election I believe....
Had the same experience in a real 737-300 while doing trim checks prior to start.
Now, the preflights I do only check to see that the trim is set.
Last edited by Airbubba; 25th Dec 2008 at 13:57.
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ALPA hid the crew in a local hotel for two days before they would allow the feds to interview and do drug tests. I'm not sure they would get away with that these days.
And yes, I think you are correct about new rules for crew pairings coming out of this accident.
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Centarus
Checking after making changes or making an input is always a good idea and yes, for a while it seemed there were incidents of trim being used and going full deflection. Exciting...
The rudder on the 737 is a very powerful flight control and it was quite easy to demonstrate that with a 60deg bank turn, one could wait until 5deg of a desired heading and with quick rudder input, you could immediately roll out. My first introduction to very powerful rudders was on the KC-135 which said something like a rudder hard-over could exceed 90deg in less than 3-5 seconds.
This was due to the rudder trim going uncommanded full scale.
Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.
Had the same experience in a real 737-300 while doing trim checks prior to start. Never trusted it after that and always double checked setting after making rudder trim changes.
The rudder on the 737 is a very powerful flight control and it was quite easy to demonstrate that with a 60deg bank turn, one could wait until 5deg of a desired heading and with quick rudder input, you could immediately roll out. My first introduction to very powerful rudders was on the KC-135 which said something like a rudder hard-over could exceed 90deg in less than 3-5 seconds.
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Huck is correct. The New York DA was looking for headlines and there was a rush to judgment. ALPA did exactly what it was supposed to do and that was defend its members from zealous government nitwits.
Unfortunately, we only have to ponder Rep Oberstar to see that big league nitwits are still in demand in politics.
Unfortunately, we only have to ponder Rep Oberstar to see that big league nitwits are still in demand in politics.
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My Take
After listening to the detailed NTSB report given in Denver it seems to me (35 years in the USA airline business as a pilot and very intimate with Continental procedures)
Being that:
I do not believe the 737 has nose gear brakes therefore this would explain the NG markings 100 feet beyond the main gear markings.
AND:
The NTSB said that all systems including engines, flight controls (including rudder placement and trim) brakes and wheels were operating normally
AND:
The inbound flight crew (who was on board as a DH crew) said they had no problems or write ups on the AC
Therefore:
Then nose gear probably shimmied to a high degree ( a very common occurrence) just prior to V1 therefore braking a stabilizer or other NG steering part locking the NG 10-30 degrees to the left. If so the Aerodynamic rudder forces would not over come the nose gear forces forcing the AC off the runway.
But we will see!!!
Being that:
I do not believe the 737 has nose gear brakes therefore this would explain the NG markings 100 feet beyond the main gear markings.
AND:
The NTSB said that all systems including engines, flight controls (including rudder placement and trim) brakes and wheels were operating normally
AND:
The inbound flight crew (who was on board as a DH crew) said they had no problems or write ups on the AC
Therefore:
Then nose gear probably shimmied to a high degree ( a very common occurrence) just prior to V1 therefore braking a stabilizer or other NG steering part locking the NG 10-30 degrees to the left. If so the Aerodynamic rudder forces would not over come the nose gear forces forcing the AC off the runway.
But we will see!!!
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beechf33a
Why was runway 25 or 26 not used since the winds were more favorable from the west? Were these runways available at the time? Why wasn't ground clearancde to one of these runways since they are both were 12000 feet? This would have elilminated the cross wind problen at runway 34L.
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Greybeard
They achieved 119 knots in less than 1900 feet. Is that within normal bounds, even given the cold temperature effect on density altitude?
1) the first officer noticed drifting off track when passing 90...93 knots.
2) runway track marks indicate a skid began at 1900 feet from threshold.
So far there is no official data linking elapsed time, distance and airspeed together, as far as I've seen, but from the above one can deduce that at 1900 feet the speed was in the order of 90 knots. The maximum recorded speed was 119 kts and Mr Sumwalt from NTSB made it reasonably clear that this was further down the takeoff run, i.e. the airplane continued to accelerate after it departed the runway centerline track.
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"Why was runway 25 or 26 not used since the winds were more favorable from the west?"
Now when did ATC ever let you take off into the wind?!?! That's not really a dig at ATC, but it always seems like there's a "preferred" runway and it's never into the wind. And, unfortunately, most pilots will just "go along" with things rather than "disrupt" the flow. However, I might add, that I was one of those who always seemed to be a "trouble maker" and request the runway 'I' wanted rather than the one "normally" used. Even if it meant I delay, I was willing to wait. I only wish more pilots would do the same. Glad I'm retired!
Now when did ATC ever let you take off into the wind?!?! That's not really a dig at ATC, but it always seems like there's a "preferred" runway and it's never into the wind. And, unfortunately, most pilots will just "go along" with things rather than "disrupt" the flow. However, I might add, that I was one of those who always seemed to be a "trouble maker" and request the runway 'I' wanted rather than the one "normally" used. Even if it meant I delay, I was willing to wait. I only wish more pilots would do the same. Glad I'm retired!
I do not believe the 737 has nose gear brakes therefore this would explain the NG markings 100 feet beyond the main gear markings.
Then nose gear probably shimmied to a high degree (a very common occurrence) just prior to V1 therefore braking a stabilizer or other NG steering part locking the NG 10-30 degrees to the left. If so the Aerodynamic rudder forces would not over come the nose gear forces forcing the AC off the runway.
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Whatever happened might have had something to do with the fire which developed very fast (source of origin??), the loss of control with the sudden noises heard and the aircraft subsequently veering to the left. The whole right side, starting from somewhere around wheel well is completely burned, the left side intact. Just makes me wonder, what was going on. Since the jet "by coincidence" departed to the left....
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CaptDoug - unfortunately there's information that the issue started well prior to V1.
35 yrs as a pilot and you're posting your version of what happened this early in the game?
35 yrs as a pilot and you're posting your version of what happened this early in the game?