Pegasus Airlines Boeing 737-800 TC-CPF overrun runway at Trabzon. All pax okay
Perhaps the pilot taxied to the left of the runway in order to execute a right turn, with the intention of using thrust from the no.1 engine to assist the right turn, with steering from the nose wheel, which lost traction as he inadvertently pushed the no.2 thrust lever forward... But that's pure speculation.
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If it is uncommanded thrust without lever movement this is a real headache for CFM and Boeing. I say without lever movement as the crew could just close the thrust lever and the problems gone. Normally EEC faults or HMU faults do not give this type of result, lets see what the black box says...
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If it is uncommanded thrust without lever movement this is a real headache for CFM and Boeing.
Lots of ifs so far. They've got the crew, all the digi boxes and a reasonably intact a/c. It shouldn't take a Sherlock.
Lots of ifs so far. They've got the crew, all the digi boxes and a reasonably intact a/c. It shouldn't take a Sherlock.
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Two telescopic cranes seen in the picture were used to remove the cabin baggage.
The airport authority awaits a heavy-lifting crane to remove the plane, and constructing a stable platform for such a crane is underway.
Please see the NTV news channel for the pictures <ntv.com.tr>
The airport authority awaits a heavy-lifting crane to remove the plane, and constructing a stable platform for such a crane is underway.
Please see the NTV news channel for the pictures <ntv.com.tr>
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It funny how 'mysterious' gets used when the involved describe an accident. As several people have speculated, its going to be one of:
a) Deselection of TR before N1 low enough and asymmetric TR stowing
b) No2 TR was INOP and power was put on No2 for some reason, as per above theories
c) PF was using asymmetric thrust to turn and pushed the wrong lever
I'll put money its not a completely uncommanded power-up.
a) Deselection of TR before N1 low enough and asymmetric TR stowing
b) No2 TR was INOP and power was put on No2 for some reason, as per above theories
c) PF was using asymmetric thrust to turn and pushed the wrong lever
I'll put money its not a completely uncommanded power-up.
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Just to put a few theories to bed. 1. Captain only steering on almost all 737s. You go left because you can see the edge better and judge it. Simples.
Steering. I've had a couple of big birds in the nose gear and the cables and NWS still worked.
It is easy (especially for crew who've flown non Boeings before to inadvertently push TOGA when you want to disconnect the autothrottle. Happened countless times before over the years and will again. If you do it, a quick expletive and then press the disconnect before thrust rises and it's not a safety issue. Pulling back the levers and not disconnecting is another matter....
Steering. I've had a couple of big birds in the nose gear and the cables and NWS still worked.
It is easy (especially for crew who've flown non Boeings before to inadvertently push TOGA when you want to disconnect the autothrottle. Happened countless times before over the years and will again. If you do it, a quick expletive and then press the disconnect before thrust rises and it's not a safety issue. Pulling back the levers and not disconnecting is another matter....
and physically hold both of them closed against the servos all the way to the flare; then hold them closed all the way down the runway until releasing just one of them prior to the excursion?
There have been a few excursions in the past where the pilot inadvertently advanced one throttle in forward while working the reverse levers on the other engines - although these have been on four engine aircraft, not twins (at least the ones I'm familiar with).
But it's at least a possibility that if the pilot didn't pull the reverser lever on the deactivated right engine, they inadvertently advanced the forward thrust lever on the right when de-selecting the left reverse lever.
A totally uncommanded thrust advance (Uncontrollable High Thrust or UHT in the lingo) is extremely rare on FADEC engines (something like 1/100,000,000 per engine flight hour), but it has been known to happen. It was more common with the pre-FADEC cable engines - usually due to a broken throttle cable...
But it's at least a possibility that if the pilot didn't pull the reverser lever on the deactivated right engine, they inadvertently advanced the forward thrust lever on the right when de-selecting the left reverse lever.
A totally uncommanded thrust advance (Uncontrollable High Thrust or UHT in the lingo) is extremely rare on FADEC engines (something like 1/100,000,000 per engine flight hour), but it has been known to happen. It was more common with the pre-FADEC cable engines - usually due to a broken throttle cable...
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They appear to be so far down the runway that we must assume the TR's had been deployed. If so, that is a not starter for cause. They must have been at a slow taxi speed by this point, so I suspect asymmetric reverse thrust would not cause this. Broken nose wheel steering might give an idea, but at slow speed the brakes should stop it PDQ, but startle WTF factor would delay size 12's entering the equation.
TDRACER, looks like it did happen on a twin: https://en.wikipedia.org/wiki/TAM_Airlines_Flight_3054
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In the company I fly for as a Captain on the 737NG 7/800 we had an aircraft which would not reduce thrust below +/- 60% when starting descent. It would show retard and the thrustlever would move to the idle position but the N1 would not reduce below 60% on one engine. It took a couple of manual thrust applications and retards to get the thrust to decrease to idle. It was a real headache for maintenance because it was initially verry intermittent and not obvious until you had a good look at it.
"Mildly" Eccentric Stardriver
There is a lot of talk here about one TR being inop and locked. I can't find the original mention of this in the thread. Can anyone point me to it please? Or is everyone following the herd?
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I managed to get a tiny stone stuck in the nose wheel steering cable pulley on a 757 that got stuck in a hard left turn just south of the tower (Romeo one?) at Gatwick a few years ago. The stone, perhaps 1/4 inch diameter had been dragged into the pulley and was holding the cable fast.
The Skipper suddenly bent double and made some deep grunting noises as he tried to turn the handle. I thought he was having a heart attack so I shouted that I was taking control and stuck the brakes on. Broad daylight but still plenty of confusion.
I wonder if the same thing happened here?
The Skipper suddenly bent double and made some deep grunting noises as he tried to turn the handle. I thought he was having a heart attack so I shouted that I was taking control and stuck the brakes on. Broad daylight but still plenty of confusion.
I wonder if the same thing happened here?
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Initial investigations seem to find the aircraft could not maintain the centre line, drifted to the left and the left gear entered the soft ground and collapsed resulting in a sharp yaw to the left, apparently compounded by right engine power. Prior to touchdown there is suggestion the the FO was pf and elected to GA, pressed TOGA but Captain took control and landed. Maybe asymmetric reverse, but looking at the pictures it is closed, which suggests any asymmetric reverse was cancelled prior to the skid, apparently most of the investigation is complete, which suggests the causes have been positively identified. Just for info, the LD with AB3 F30 1874 AB2 F30 2417 with one reverser inoperative, or 2197 AB2, 1708 AB3 same condition. If the aircraft touched down deep this may explain why they are close to the end at the time of the incident. The waters are really getting muddy!
Last edited by Avenger; 16th Jan 2018 at 05:38. Reason: info