The prevailing situation:
The FedEx MD-11 was approaching runway 34L at Tokyo Narita, with fairly high gusting winds forecasted. Gusting winds always raise the spectre of potential windshear, and Narita is renowned for it.
The forecast wind (320deg at 26kt gusting to 40kt) would have provided a crosswind from the left that was some 20deg off the runway heading, although that may not have been what actually prevailed on landing.
So although it was not going to be particularly easy to land any aircraft type in an elegant way that day, the conditions were far from extreme and the visibility was excellent.
Now watch the video below, be ready to pause it from time to time to examine the very rapid transition from a relatively normal landing to a disastrous one, and then check the text below for my interpretation of what you are seeing at each point:
The landing sequence shown in the video tells us the following:
1. On the last part of short final approach
1. On the last part of short final approachthe aircraft appears to be stable, if slightly low, with wings level and a normal pitch attitude for the circumstances (given that we don’t know what the airspeed is);
2. the touchdown is very firm, but under gusty circumstances the pilots would naturally aim for a firm touchdown;
3. the nosewheel was lowered onto the runway at a high rate. Although the crew would want to put the nosewheel on the runway quickly to stop the aeroplane flying, the rate at which it was lowered might have threatened damage to the nose-gear – but it looks as if it survived the impact anyway.
Note: up until this point the aircraft’s landing performance and behaviour has been well within the normal range. But then:
4. immediately following nosewheel touchdown the aircraft pitched up dramatically and the aircraft ballooned into the air again.
Note: the rate at which the nosewheel was lowered may have been a part of the cause of the pitch-up following nose oleo compression, and that pitch-up might also have been exacerbated by the automatic extension of the spoilers which, in this type, are renowned for producing a pitch-up moment;
5. Now the aircraft is airborne again. This ballooning following first touchdown might have been made worse by a sudden gust of wind, momentarily raising the airspeed. But if that were true, the spoilers would have been simultaneously destroying a lot of the lift, and producing considerable drag; so, as the gust died (if it did) the aircraft might have been at or below stalling speed;
6. then – and this is what leads to disaster – the nose drops and stays low until the nosewheel’s impact with the runway. This happens either because of lack of elevator authority, or because the pilot flying was tempted into a classic pilot induced oscillation.
Note: there are no circumstances under which a pilot of any type should deliberately select a nose-down attitude at that point – if, indeed, pilot selection of the nose-down attitude is what actually happened. During ballooning following touchdown the nose MUST be held up (if the elevator authority allows it) and appropriate power applied, whether the crew are trying for a successful second touchdown or for a go-around.
7. finally the nosewheel hits the ground extremely hard and the nose instantly rebounds upward, the main gear touching the surface momentarily a fraction of a second later. Almost simultaneously, the aircraft begins its fatal bank to the left, from which recovery was impossible once the left wingtip had hit the ground.
Note: banking to the left is not what the forecast crosswind would have been expected to produce. Normally, especially in a swept-wing aircraft like this one, the upwind wing has a tendency to lift, but in this case it didn’t. So the crosswind does not appear to be the critical factor here, although windshear is very likely to be one of the causal factors.
For all those with different interpretations (or even to agree), please feel free to file your comments,