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Whoops Apocalypse!

Here’s a detailed report of what appears to have been quite a close call. Afghanistan-based Kam Air’s overloaded plane nearly didn’t make it. You don’t need to be a technical expert to figure out what would happen if 143,700 lbs of aircraft fuel hits the deck.

Kam Air DC86 at Manston on Aug 11th 2010, tail strike on takeoff

A Kam Air Douglas DC-8-60, registration YA-VIC performing a cargo flight from Manston, EN (UK) to Buenos Aires, BA (Argentina) via Cape Verde Islands with 3 crew and 9 passengers, struck its tail onto Manston’s runway 28 during takeoff. The crew continued to Cape Verde Islands where evidence of the tail bumper contacting ground was discovered.

Inspection revealed the energency absorber had received deformation which however had remained within limits, no further inspection was required, and the airplane continued the flight to Buenos Aires.

The United Kingdom’s Air Accident Investigation Branch released their Bulletin reporting, that Kam Air had acquired two DC-8s from an operator in the United Arab Emirates. The flight from Manston to Buenos Aires carrying 36 polo ponies. For the flight the aircraft was carrying two complete crews.

The flight engineer determined the cargo weight at 43,409 lbs, the aircraft carried 143,700 lbs of fuel – despite the computed minimum fuel required to Cape Verde being 97,661 lbs including a diversion – bringing the aircraft’s takeoff weight to 343,346 lbs. The flight engineer entered a maximum takeoff weight of 349,000 lbs into the load sheet, however it was unclear how he arrived at that figure, the actual structural maximum takeoff weight is 358,000 lbs. The center of gravity was computed at 22.8 percent MAC which is about in the middle of the permitted range. Using the load sheet V1 was computed at 143 KIAS, Vr at 160 KIAS and V2 at 172 KIAS.

The performance table for Manston’s runway 28 provided a takeoff weight limit of 317,300 lbs for the selected takeoff flap setting, thus the aircraft was 25,700 lbs (11,670 kg) over weight for takeoff from Manston’s runway 28. The use of flap 23 would have increased the weight limit by 10,600 lbs. The flight engineer however did not refer to the runway performance tables.

The captain (55, ATPL, 15,000 hours total, 3,000 on type) was pilot flying for the sector, the runway was dry, temperature at 20 degrees C, winds came from 290 degrees magnetic at 7 knots.

A number of airport staff including loaders, air traffic controllers and operations staff commented that the airplane appeared to be slow on acceleration. The aircraft rotated near the runway end, a cloud of debris was thrown up as the aircraft climbed away.

The captain later reported he was aware of two jolts as the aircraft lifted off and suspected a tail strike had occurred. Subsequent inspection showed the aircraft had left a scrape mark on the runway that extended beyond the runway end onto soft ground. Manston’s Air Traffic Control suspected a tail strike and relayed the info to the crew via London ATC. With all aircraft systems appearing normal the captain decided to continue the flight to Cape Verde, where the tail strike was confirmed.

Scrape marks began 35 meters before the runway end (runway’s takeoff distance available 3,112 meters) over the next 24.6 meters, followed by a 23.8 meters long gap which however contained a destroyed center line lighting fitting, and continued as an up to 23cm deep trench in soft soil, the total length of the ground marks was 117.5 meters. The marks were consistent with the contact of a sole plate of the tail skid assembly. The center line light fitting was destroyed by contact with the right hand main gear.

The flight data recorder showed that rotation began at 159 KIAS consistent with the 160 KIAS target. The aircraft reached 8 degrees nose up pitch in the next 5 seconds and continued to increase at a constant rate until 11 degrees where a marked reducting in pitch rate occurred. A significant aft control input was made at that time after which the pitch continued to increase to a maximum of 15.2 degrees nose up. The AOM indicates tail strike would occur at 8.95 degrees nose up leading the conclusion, that the airplane had already just become airborne when the tailstrike occurred at 11 degrees nose up.

The AAIB analysed that the computer generated flight plans showed less fuel than actually necessary. The predictions by the computer flight plans were about 19% less than the actual fuel burn. The crew however increased the fuel amount by 47% which seems excessive.

The UK Government’s Department of Transport decided upon receiving the AAIB report as well as information from a number of other sources that Kam Air would receive no further operating permits on UK soil for its DC-8 fleet and notified the European Union. Following ramp checks and the information from the UK government the European Union decided to put Kam Air onto the list of operators which are prohibited from operating in the European Union (published by Nov 23rd 2010).

ICAO reported that due to the travel restrictions imposed by the United Nations it had not been possible to perform an audit of Afghanistan’s state aviation regulatory structure.

Four safety recommendations dealing with the audit of state regulatory bodies, where audit by ICAO can not be assured, have been released as result of the investigation.

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