The pilots on Air France flight 7775 ditched the plane after ingesting a bird in the number one engine. Why?

Question

Good point.

I should have written "aborted the flight" NOT "ditched the plane".

Answer 1

They didn't "ditch" the aircraft. They followed fairly common aviation standards of regarding this incident.

"The aircraft (F-GMPG), on a scheduled flight from Pau to Paris Charles de Gaulle, was cleared for takeoff at 11:15am local time. The takeoff roll was normal. Just after the Fokker became airborne, a bird was apparently ingested into the number one engine. The flight crew chose to abort the takeoff, touched back down, but were unable to stop prior to reaching the end of the runway. The jet vacated the runway and collided with a passing truck, killing the driver. The airplane then slid to a stop in a field."
-ref. AirDisaster.com

As to why this would happen:

1) Bird strikes can be very serious to an aircraft, a bird could easily damage or shutdown a turbojet aircraft's motor. The air intake fans can be damage by reasonably small things. Even loose chunks of ice can damage an engine.

2) Take-off roll and lift-off are considered critical stages of flight. A dangerous situation developing during lift-off can be deadly, so the pilots choose to abort their take-off and put the aircraft back on the runway. However, they apparently, were going to fast to stop on their remaining amount of runway.

3) That aircraft has 2 engines. While an aircraft "CAN" fly with relative safety with one engine out...taking off with one engine out is not safe. Take-off has some characteristics that greatly differ from normal airborne flight. First, at take off, the aircraft will actually begin flying at a slower then required airspeed for flight because of something known as ground effect. Take offs are also periods of maximum thrust for an aircraft. If the pilots had tried to continue their take off, they would have had a lot of torque 'twisting' the plane as they departed. If they would have continued their climb out, they quite possibly would have experienced a stall and possibly spiral the aircraft...which would have been a much worse accident. They seem to have done the safest course of action they could in regards to aborting their take off.

Answer 2

Your question is very relevant.

While ingestion of a bird or other 'Foreign Object', is not conducive to performance, proper control of the Aircraft is paramount in the Pilot's responsibilities.

An aircraft takes of when it's speed reaches Vrot, or the speed at which the aircraft will fly by lifting the nose. This is a function of A/C weight, temperature, humidity, power available, etc.

Other parameters considered in the Take Off Roll are, Vs Stall Speed the aircraft will fly but be unstable, Vmc, minimum control speed with the loss of one engine, Vr Minimum velocity of refusal, and others.

Of these the most important is Vr. The criteria includes runway length and the A/C's ability to stop in that length. That is very important because if you reach Vr before you reach Vrot, you are committed to take off and you do not abbort unless the wings or landing gear falls off.

That was a factor in the Concorde crash. It was exacerbated when the F/E shut down a functioning engine with out instructions from the pilot in command.

I am not privy to what made this pilot choose to land but either he had a very long runway remaining, which doesn't seem to be the case or he screwed up.

A board will decide.

Answer 3

Since he didn't make it, probably 'failure to follow briefed procedures'. Most commercial aircraft on most commercial runways reach V1 before Vr, so if he was airborne he was probably well past his decision point and accelerating towards V2 and climbing out.

Before takeoff our test pilots would run through their speeds and brief on what they would do if faults occurred at particular stages. V1 is your go/no go speed. Below V1 if you lose an engine or blow a tire you abort and stay on the ground. Above V1 it is normal to brief to continue come what may, unless you lose two engines, in which case this isn't a flying day no matter what you do. We were in the very unusual position of having a lot of runway and a light aircraft, so we could abort back onto the runway, but that's very unusual.

Theory is all very well, but put a pilot in a plane 20 feet of the ground with a dead engine and a heavy load and maybe he'll just chop power and drop it back onto the ground. But he will have been trained to continue on one engine.

But the practice isn't necessarily as easy as the theory. An Evergreen 747 flying as Japan Air 46E out of Anchorage (PANC) lost an engine in severe turbulence and had a pretty hard time making it back to the airfield safely (see link below, very dramatic transcript towards the end). So you can understand a pilot might be reticent about taking his passengers on an unsafe ride if he judged he could get down safely. But this time he was wrong.

Answer 4

They were playing it safe. A bird can cause serious damage to a jet engine.

Answer 5

They didn't ditch it. They're French, they surrendered the aircraft to the bird.