Continental 737 Off Runway at DEN
Sudden Left Turn at 103 kt
The first officer has also told investigators that the plane was pulling away from the center line as it reached about 103 mph before taking a sudden left turn off the runway.
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snowfalcon2
You don't need anecdotes for this. It's very common at stop signs and traffic lights, where automobile exhaust pipes melt snow and/or ice while waiting, it freezes and the next car slides right through and into cross traffic.
If this is what you mean, the pilots could well have hit black ice while something else was going wrong and it was just one more thing they didn't need to deal with. Obviously, not *the* cause, but part of the chain of events.
There are some anecdotes that hot jet exhausts could cause loose snow on the runway to melt and freeze to ice. Would affect the rotation zone where the exhausts are directed downwards. Don't know if it's pure BS or something which might only occur with afterburner heat.
If this is what you mean, the pilots could well have hit black ice while something else was going wrong and it was just one more thing they didn't need to deal with. Obviously, not *the* cause, but part of the chain of events.
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Fright Recorder Power
3G cutoff of recorder power does seem lower than needed. But this is FAA, where 50G SLF bodies are strapped in place with 9G belts and who knows what strength seat rails.
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PJ2: "Likely so in the scenario I image - the recording devices would simply keep falling back on the "next" source of power until the last source, likely battery-backup, was exhausted, say, after 10 or 15 minutes. Likely longer wouldn't be needed because an airplane at that stage of electrical capability isn't going to be in the air long. (That said, there have been some interesting A320 DC Essential Bus failures, (DFDR is powered by the AC1 bus), which have blacked-out all or partial instruments, as we know). I note for example, that the Bombardier Global Express accident report cited above, indicates that the DFDR is powered by the DC Essential Bus - that type of bus, as indicated by it's name, is "normally" a backup power source for the main DC busses for essential services only so it appears as though Bombardier has considered this scenario - I'm guessing here of course."
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Transport aircraft, as you know, have AC generators on the engines and APU, and use rectifiers to power the DC buses. Essential buses typically have multiple power sources, as does the Emergency DC or Battery Bus. Adding non-emergency items to the battery bus requires installing a larger capacity battery, to maintain the 30 minutes or so required operation after the generators quit. Rolling the dice, you can see the wisdom of not putting the DFDR and CVR on the battery bus, especially the older motorized recorders.
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.
GB
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PJ2: "Likely so in the scenario I image - the recording devices would simply keep falling back on the "next" source of power until the last source, likely battery-backup, was exhausted, say, after 10 or 15 minutes. Likely longer wouldn't be needed because an airplane at that stage of electrical capability isn't going to be in the air long. (That said, there have been some interesting A320 DC Essential Bus failures, (DFDR is powered by the AC1 bus), which have blacked-out all or partial instruments, as we know). I note for example, that the Bombardier Global Express accident report cited above, indicates that the DFDR is powered by the DC Essential Bus - that type of bus, as indicated by it's name, is "normally" a backup power source for the main DC busses for essential services only so it appears as though Bombardier has considered this scenario - I'm guessing here of course."
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Transport aircraft, as you know, have AC generators on the engines and APU, and use rectifiers to power the DC buses. Essential buses typically have multiple power sources, as does the Emergency DC or Battery Bus. Adding non-emergency items to the battery bus requires installing a larger capacity battery, to maintain the 30 minutes or so required operation after the generators quit. Rolling the dice, you can see the wisdom of not putting the DFDR and CVR on the battery bus, especially the older motorized recorders.
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.
GB
Have toolbox, will travel
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The question I have is this, do COA 737 pilots fly all types of 737 at that airline? Do the 737NG guys fly the 737 Classics too or are they a different bid location?
Just curious what kind of recent experience that crew had with the handling aspects of a Classic with winglets fitted... Seems COA just started adding them to the older 737 fleet.
Just curious what kind of recent experience that crew had with the handling aspects of a Classic with winglets fitted... Seems COA just started adding them to the older 737 fleet.
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Originally Posted by Belgique
The jet's tires began making marks indicating a possible skid after it had traveled 1,900 feet, Sumwalt said.
(part1; 00:55 - 01:22)
"The beginning of the tyre marks began ninteen hundred feet from the threshold (from the beginning) of runway three-four right. So the main landing gear started showing rubber on the runway nineteen hundred feet from the beginning of the runway. Now, 100 feet past that is when the nose gear started showing tyre marks on the runway."
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
they are each approximately 15 mins long.
Last edited by theron; 24th Dec 2008 at 17:54.
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The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.
The original 737 trim switch had a rectangle on top of it and it was near where the jumpseater would rest his/her feet. It was VERY easy to run the trim full deflection and the indicator was not the most easily visible indicator on the airplane.
Lots of problems including crew duty, rushing, inexperience, missed items on checklilst... not pretty.
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Not likely a crew would reject for a blown tyre. It must have been more significant? Certainly not at high speed.
Not an easy decision when near V1, the whole airplane is shaking and you are accelerating at 7-10kts/sec. Offers a very confusing picture to the pilot.
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Overhead photo doesn't show the shadows of the Spoilers that would have been required/deployed during an RTO (B737 AFM). If the right engine is still in reverse, wouldn't the flight spoilers still be up? (possibly retracted during Evac items)
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Sudden left turn
Just speculating, but maybe something hit the steering cables (again).
An offset nosewheel caused the 737 in this incident to depart the runway after landing. Was because of a birdstrike on the steering cable during take-off. Check out the photo's on page 3; feathers still visible.
An offset nosewheel caused the 737 in this incident to depart the runway after landing. Was because of a birdstrike on the steering cable during take-off. Check out the photo's on page 3; feathers still visible.
Buttonpusher
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The question I have is this, do COA 737 pilots fly all types of 737 at that airline? Do the 737NG guys fly the 737 Classics too or are they a different bid location?
The question I have is this, do COA 737 pilots fly all types of 737 at that airline? Do the 737NG guys fly the 737 Classics too or are they a different bid location?
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Nose Gear?
Well, if the nose gear (at last report) is still buried under the nose, perhaps examination of it will shed some light once they lift the fuselage.
I once wrote up a nose wheel shimmy on takeoff and the mechanic at the next station called me over once they got the nose jacked up. He said, "Watch this", and took one of the nose tires in both hands and shook it side to side. The scissor link had somewhere on the order of .25 - .50 inch of play, instead of the "normally" acceptable few thousandths of an inch. The mechanic said that that much play could have resulted in a failure on my next takeoff. As he put it, "You'd be in the grass so fast you wouldn't know what happened."
I once wrote up a nose wheel shimmy on takeoff and the mechanic at the next station called me over once they got the nose jacked up. He said, "Watch this", and took one of the nose tires in both hands and shook it side to side. The scissor link had somewhere on the order of .25 - .50 inch of play, instead of the "normally" acceptable few thousandths of an inch. The mechanic said that that much play could have resulted in a failure on my next takeoff. As he put it, "You'd be in the grass so fast you wouldn't know what happened."
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Swedish Steve
A 100,000+lb aircraft bouncing on a squirl? Perhaps.
I pushed back a B777 in the summer and we forgot to remove a rubber chock behind the mainwheel.
We didn't notice it until we passed it in the tug!
Friend had a thump on rotation in a 727. Banging noises aren't that uncommon(unloaded strut hitting bump, etc).
Doing next preflight F/E finds the remains of a deer in the nose gear.
A 100,000+lb aircraft bouncing on a squirl? Perhaps.
I pushed back a B777 in the summer and we forgot to remove a rubber chock behind the mainwheel.
We didn't notice it until we passed it in the tug!
Friend had a thump on rotation in a 727. Banging noises aren't that uncommon(unloaded strut hitting bump, etc).
Doing next preflight F/E finds the remains of a deer in the nose gear.
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tire-marks (significance thereof)
"The beginning of the tire marks began nineteen hundred feet from the threshold (from the beginning) of runway three-four right. So the main landing gear started showing rubber on the runway nineteen hundred feet from the beginning of the runway. Now, 100 feet past that is when the nose gear started showing tire marks on the runway."
Distinctive main-gear tire marks on a runway would seem to indicate either a skid or the marks left by a mostly deflated (then suddenly failing/failed/and thereafter flailing) tire remnant. To what extent such an event (one good and one failed tire) would produce a marked swerve in a significant crosswind? More to the point, whether a failed tire readily (or rapidly) then induces its companion tire to fail? That would depend on the speed, roll distance and the effect of anti-skid braking. You can debate the physics forever and that's about all you can do - because few of us have ever been in such a suddenly deteriorating situation on takeoff. Two failed tires on one side, soon after abort initiation, would definitely do it however. The swerve would be uncontrollable.
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An unusual bumping and rattling noise on takeoff - that changed its cadence and severity/amplitude with increasing speed - would be instinctively associated (by the handling pilot) with an undercarriage (i.e. failing tire) source. At any point below V1 such an abnormal noisy situation would be most likely to promote an abort decision (in most cockpits I've flown in)..... no matter what the boeing scribblies might say or recommend.
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wileydog3
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Quote:
The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.
The rudder trim WAS mis-set and full deflection. Power was added slowly and there was a problem of crew communication. The Capt then tried to correct the drift with the nosewheel steering which also was ineffective. At that point, an abort decision was made and the aircraft went off the end of the runway.
Wileydog3 - The rudder problem didn't cause them to go off the side of the runway. Failure to abort in a timely manner caused them to go off the end of the runway.
V1 = 125 kts, Vr = 128 kts. Throttles retarded at 130 kts. Departed end of runway at 34kts.
ASN Aircraft accident Boeing 737-401 N416US New York-La Guardia Airport, NY (LGA)
Interesting, one NTSB board member dissented. Disapproved of an a/c commander only having 5500 hrs TT(2600+ in type). FO's time not mentioned.
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Quote:
The plane went off the end of the runway, as wikipedia says it did, because they aborted too late. The rudder trim did not cause them to leave the side of the runway. That's a huge difference.
The rudder trim WAS mis-set and full deflection. Power was added slowly and there was a problem of crew communication. The Capt then tried to correct the drift with the nosewheel steering which also was ineffective. At that point, an abort decision was made and the aircraft went off the end of the runway.
Wileydog3 - The rudder problem didn't cause them to go off the side of the runway. Failure to abort in a timely manner caused them to go off the end of the runway.
V1 = 125 kts, Vr = 128 kts. Throttles retarded at 130 kts. Departed end of runway at 34kts.
ASN Aircraft accident Boeing 737-401 N416US New York-La Guardia Airport, NY (LGA)
Interesting, one NTSB board member dissented. Disapproved of an a/c commander only having 5500 hrs TT(2600+ in type). FO's time not mentioned.
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sorry wiley
I don't buy the misset rudder trim
I have more than 17k hours in 737, I ve never seen this happen
I don't buy the misset rudder trim
I have more than 17k hours in 737, I ve never seen this happen
read the probable cause of the LGA crash here...
ASN Aircraft accident Boeing 737-401 N416US New York-La Guardia Airport, NY (LGA)
Mis-set rudder trim may not have played a part in this DIA crash but I am familiar with the LGA accident..
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misd-agin.. don't know how to say this any other way but the mis-set trim contributed to the accident and yes, they aborted late and yes they went off the END of the runway, not the side. But during the roll there were excursions.
As for an NTSB dissenter and arguing 'only 5500 hrs' one would have to wonder what his position would be today with some 121 carriers.
As for an NTSB dissenter and arguing 'only 5500 hrs' one would have to wonder what his position would be today with some 121 carriers.
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The rudder trim WAS full scale deflected on the LGA crash. And the round knob on the rudder trim replaced the old one with the rectangle.
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. 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.
As for an NTSB dissenter and arguing 'only 5500 hrs' one would have to wonder what his position would be today with some 121 carriers.
Actually, as I recall, the LGA accident was the catalyst for requiring consolidation hours after IOE before being paired with another crewmember new in type.