By David Learmount
This Afriqiyah Airlines crash at Tripoli was not an ordinary approach accident.
Ordinary approach accidents that involve an impact with flat terrain in the last kilometre before the runway threshhold do not usually smash the aeroplane into tiny pieces. They normally leave it crumpled but more or less complete, or otherwise the structure fractures into large but recognisable components.
The tail fin's completeness in this case doesn't count: the fin is a monolithic composite structure of considerable strength that tends to snap off in impacts. So what kind of impact was this to break the rest of the aircraft up so totally? The debris field does not look as if the aircraft cartwheeled, and if it had done there would normally still have been some recognisable large components.
The hull of the Turkish Airlines Boeing 737-800 accident on final approach to Amsterdam Schiphol in February 2009 was fractured but completely identifiable. That aircraft impacted flat, clear terrain about the same distance from the runway. The Turkish 737 stalled into the ground with a high rate of descent and very low forward speed.
The undeniable fact is that the Afriqiyah aircraft impact was particularly high-energy.
The Airbus A330 has a terrain awareness warning system that would have alerted the crew to a high terrain closure rate, and its flight envelope protection system would have prevented the aircraft from stalling unless the crew had de-selected the "normal" flight control law, but there is no information to suggest that they would have had a reason to do that.
The weather was not challenging, in the sense that the visibility was adequate, there was little or no cloud and the wind was gentle. There is no suggestion of a technical snag because the crew did not report an emergency. The pilots were on the last leg of a long, uneventful night flight, arriving at their home airport.
The general visibility was 6km, although there is a suggestion that about the time of the accident the visibility dipped to 2km in haze. The pilots were flying an approach to runway 09 (due east) a few minutes before dawn, but being above sea level they would have had the sun shining into their eyes through the brightening haze, which can provide the crew with an impression of hanging in the sky with no sense of speed, no external visual references, with the ground beneath them almost invisible in the pre-dawn shadow.
Although technically the visibility would have allowed the crew to see the runway from at least 2km, it was probably invisible to them because the haze was illuminated, the pilots were dazzled by the sun's bright red disc, and the runway was in shadow.
It is not clear what approach aid the crew were using, but a precision aid like ILS was not available for 09, so the pilots had no glideslope guidance. They would have been tired after an all-night flight of more than eight hours, and looking forward to going home.
Having the dawning sun in your eyes when you are very tired after flying all night makes your eyelids feel like lead.
Flying into the low, rising sun near your home base at the end of a night flight is perhaps the most overpoweringly soporific combination of circumstances known to man.
The aircraft, we know, flew into the ground.
If it flew into the ground without any control inputs whatever to arrest the rate of descent, that could explain the degree of damage.