"It's not a surprise, there are many suspicions about what happened," Essam Ahmed, said yesterday. He said he would not be surprised if a criminal investigation followed.
Questions remain about why the pilot apparently left the cockpit and over suggestions that the co-pilot said a prayer before the Boeing 767's autopilot was disengaged and the aircraft dived into the Atlantic Ocean south of Nantucket island in Massachusetts.
Mr Ahmed said it was hard to gauge the significance of the prayer. If the co-pilot said the shihada, a short declaration of faith in Islam, it could suggest a looming crisis. "Someone would say say the shihada if there was a hopeless case, so he would ask God to help. But we need to know what was said just before and after it," said Mr Ahmed, a pilot with 30 years' experience.
Ashraf Hussein, an EgyptAir pilot since 1985 who knew the pilots on Flight 990, said it was unusual for the captain, Ahmed al-Habashi, to have left the cockpit so early in the flight - the jet had taken off from New York bound for Cairo less than an hour before the crash.
"I would leave my seat after two hours at least, not one hour... I would doubt he left his seat at that point, unless he went to the toilet," Mr Hussein said. "They had only been airborne for around 55 minutes, the aircraft was only just over the ocean."
Incidents in which pilots have taken passengers to their doom include the December 1997 crash of a Singapore Airlines subsidiary SilkAir. The Boeing 737 dropped from almost 35,000 feet into a river bed on the Indonesian island of Sumatra after the flight data recorder and cockpit voice recorder were switched off. The investigation focused on the captain, Tsu Way Ming, who was reportedly in financial difficulties and had taken out a substantial life insurance policy.
In August 1994, a pilot crashed a Royal Air Maroc ATR-42 on a domestic flight into the Atlas mountains after apparently having an argument with his female co-pilot. Press reports of their last conversation picked up on the cockpit voice recorder were not officially confirmed by the investigation. All 44 passengers and crew were killed.