MS990

EgyptAir Flight 990 was a scheduled flight from Los Angeles International Airport to Cairo International Airport, with a stop at John F. Kennedy International Airport, New York City. On October 31, 1999, the Boeing 767-300ER operating the route crashed into the Atlantic Ocean about 60 miles (100 km) south of Nantucket Island, Massachusetts, killing all 217 passengers and crew on board, making it the deadliest aviation disaster for EgyptAir. Since the crash occurred in international waters, it was investigated by the Ministry of Civil Aviation's Egyptian Civil Aviation Agency (ECAA) and the American National Transportation Safety Board (NTSB) under International Civil Aviation Organization rules. Since the ECAA lacked the resources of the NTSB, the Egyptian government asked the American government to have the NTSB handle the investigation.

Two weeks after the crash, the NTSB proposed that it hand the investigation over to the United States Federal Bureau of Investigation (FBI), as all of the evidence that they had collected up until that point suggested that a criminal act had taken place, and that the crash was the result of an intentional act. The Egyptian authorities refused to accept this idea, and repeatedly declined the proposal to hand the investigation over to the FBI. As a result, the NTSB was forced to continue the investigation alone, despite it falling outside their investigative purview.

The NTSB found that the cause of the accident was the airplane's departure from normal cruise flight and subsequent impact with the Atlantic Ocean "as a result of the relief first officer's flight control inputs". However they were ultimately unable to determine any specific reason for his alleged actions. The ECAA independently concluded that the incident was caused by mechanical failure of the aircraft's elevator control system. The Egyptian report suggested several possibilities for the cause of the accident, focusing on the possible failure of one of the right elevator's power control units. However, the NTSB continues to dispute the findings of the ECAA report, claiming that there is no possible explanation for the flight's final movements, other than an intentional human act.

INVESTIGATION

Defection of Hamdi Hanafi Taha 

In February 2000, EgyptAir 767 captain Hamdi Hanafi Taha sought political asylum in London after landing his aircraft there. In his statement to British authorities, he claimed to have knowledge of the circumstances behind the crash of Flight 990. Taha attested that first officer Gameel Al-Batouti had intentionally crashed the plane to exact revenge on an airline executive, who had recently demoted Al-Batouti, and happened to be on board. Taha also is reported to have said that he wanted to "stop all lies about the disaster," and to put much of the blame on EgyptAir management.

Osama El-Baz, an adviser to Egyptian President Hosni Mubarak, said, "This pilot can't know anything about the plane; the chances that he has any information [about the crash of Flight 990] are very slim." EgyptAir officials also immediately dismissed Taha's claim. American investigators confirmed key aspects of Taha's information, but decided not to anger the Egyptian government further by issuing any official statement about Al-Batouti's motive. EgyptAir terminated Taha's employment, and his application for British asylum was reportedly declined, though he gave an extensive 2002 newspaper interview in London and was featured in a 2005 documentary.

NTSB investigation and conclusion 

The NTSB investigation centered on the actions of the relief first officer, Gameel Al-Batouti. The NTSB determined that the only way for the observed split elevator condition to occur was if the left seat pilot (the captain's position) was commanding nose up while the right seat pilot (the first officer's position) commanded nose down. As the Egyptian investigation forwarded various mechanical failure scenarios, they were each tested by the NTSB and found not to match the factual evidence. The NTSB concluded that no mechanical failure scenario either they or the Egyptian investigation could come up with matched the evidence on the ground, and that even if mechanical failure was a factor, the 767's design would have made the situation recoverable.

The NTSB's final report was issued on March 21, 2002, after a two-year investigation. The NTSB concluded that the probable cause of the crash was the relief first officer's actions, but it did not determine the reason for those actions.

From the NTSB report's "Summary" section:

1. The accident airplane's nose-down movements did not result from a failure in the elevator control system or any other airplane failure.

2. The accident airplane's movements during the initial part of the accident sequence were the result of the relief first officer's manipulation of the controls.

3. The accident airplane's movements after the command captain returned to the cockpit were the result of both pilots' inputs, including opposing elevator inputs where the relief first officer continued to command nose-down and the captain commanded nose-up elevator movements.

From the NTSB report's "Probable Cause" section:

The National Transportation Safety Board determines that the probable cause of the EgyptAir flight 990 accident is the airplane's departure from normal cruise flight and subsequent impact with the Atlantic Ocean as a result of the relief first officer's flight control inputs. The reason for the relief first officer's actions was not determined.

ECAA investigation and conclusion 

After formally ceding responsibility for the investigation of the accident to the NTSB, the Egyptian authorities became increasingly unhappy with the direction the investigation was heading, and launched their own investigation in the weeks following the accident. The ECAA report concluded that "the Relief First Officer did not deliberately dive the airplane into the ocean" and that mechanical failure was "a plausible and likely cause of the accident".

William Langewiesche, an aviation journalist, said: "[I]n the case of the Egyptians, they were following a completely different line of thinking. It seemed to me that they knew very well that their man, Batouti, had done this. They were pursuing a political agenda that was driven by the need to answer to their higher-ups in a very pyramidal, autocratic political structure. The word had been passed down from on high, probably from Mubarak himself, that there was no way that Batouti, the co-pilot, could have done this. For the accident investigators in Egypt, the game then became not pursuing the truth, but backing the official line.

Responses to reports

he NTSB investigation and its results drew criticism from the Egyptian government, which advanced several alternative theories about mechanical malfunction of the aircraft. The theories proposed by Egyptian authorities were tested by the NTSB, but none was found to match the facts. For example, an elevator assembly hardover (in which the elevator in a fully extended position sticks because the hinge catches on the tail frame) proposed by the Egyptians was discounted because the flight recorder data showed the elevator was in a "split condition". In this state, one side of the elevator is up and the other down; on the 767, this condition is only possible through flight control input (i.e., one yoke is pushed forward, the other pulled backward).

Some evidence indicated that one of the right elevator's power control units may have suffered a malfunction, and the Egyptian investigation mentioned this as a likely cause of the crash. While noting that the damage did indeed exist, the NTSB countered that it was more likely a result of the crash rather than a pre-existing problem, as the 767 is designed to remain airworthy even with two PCUs failed.