Tripoli Crash Resulting From a Fatal Combination of Factors

There is a telling indicator of what may have happened as the Afriqiyah Airways A330 attempted to land at Tripoli airport on 12 May. Amid the shattered wreckage on the approach to runway 09, the largest piece is the tail – and it’s pointed backward to the line of flight.

Intended runway is to the left (east) in this photo.

Intended runway is to the left (east) in this photo.

That positioning indicated that the airplane cartwheeled on impact. If there was a need to bank late in the approach to line up with the runway, at that low altitude there is the potential to dig in a wing-tip and cartwheel. If the handling pilot hit take-off go-around (TOGA) thrust at the last moment to avoid ground contact, that would guarantee the cataclysmic extent of the cart-wheeling break-up. An Alitalia crew saw the Afriqiyah A330 looming out of the mist on finals and reported it was banked in a nose-down attitude, about to hit in the underrun.

Crash site relative to Tripoli's airport, looking east.

Crash site relative to Tripoli's airport, looking east.

What would lead the pilot to be low enough to hit the ground with a wingtip? There is a pronounced upslope in the first third of the runway. The effect of this first third and limited runway field of view in poor visibility (dawn at the time of the crash, about 6 a.m.) is an illusion that will cause the pilot to undershoot. The undershoot results as the pilot descends in his attempt to maintain a normal visual approach angle – and he has no VASI (visual approach slope indicator) or PAPI (precision approach path indicator) to help guide him. Nor is runway equipped with ILS (instrument landing system). Runway 27 at Tripoli, the reciprocal of runway 09, was ILS equipped.

The obvious question: why wasn’t runway 27 used instead? At that time of day, planes landing on runway 27 approach from the east. In other words, they come out of the rising sun, as viewed from the control tower. As one account has it: “They [air traffic controllers] find this unpleasant.” So airplanes are directed to use runway 09. That means pilots fly into the sun and haze at dawn. In this case, that approach from the east meant a tailwind, which would tend to flatten the approach. Add the appearance of the first third of the runway, nil navigation aids, and maybe a bit of fatigue from flying all night from Johannesburg, South Africa, and one has the makings of an accident.

The airplane’s TAWS (terrain awareness and warning system) was of marginal utility. As one pilot remarked:

“Looking at the terrain clearance floor … the floor rises from 0 feet a short way from the runway to 400 feet at 5 NM. If you flew a 3 degree slope to the ground at 1 NM it looks unlikely that you would get any warning and, if you did, it would be a very late one!”

At times of sunset and sunrise, the pilot’s prevailing visibility can be very directional. For instance, a pilot landing into the west around sunset can easily “lose it” in the flare. Cloud isn’t a factor and most likely wasn’t in this case in Tripoli. Here’s guessing the pilot dragged in low on approach, lost it in the glare, and dug in a wing-top. Of the 104 passengers and crew aboard, 103 died.

As the saying goes, Occam’s razor cuts deep when illusions are in play.