The crash of an Egyptair passenger jet early Sunday morning, apparently killing all 217 people on board, raises troubling issues, both in relation to the safety of airplane manufacturing and airline operations, and to the possibility of a cover-up of aspects of the disaster by the US and Egyptian governments.

The crash of Egyptair Flight 990 was the third such tragedy in three years for a passenger jet taking off from John F. Kennedy Airport in New York City for a transatlantic flight. It follows the June 1996 explosion which destroyed TWA Flight 800, in which 230 died, and Swissair Flight 111, which crashed into the Atlantic in September 1998, while trying to make an emergency landing in Halifax, Nova Scotia, killing 229 people.

All three jets were built by Boeing, although they were different models. TWA Flight 800 was a Boeing 747 and the Swissair jet was an MD-11, built by McDonnell-Douglas before it was taken over by Boeing. The Egyptair jet was a Boeing 767.

While more than 1,000 flights a day originate at Kennedy, many of them taking the transatlantic route, the loss of three flights in three years with a combined death toll of 676 inevitably suggests that there are unexamined problems with airline operations there. No other airport in the world has had such a series of disasters.

While in most air crashes there is some indication beforehand of mechanical difficulty or human error, suggesting a probable cause, both the TWA and Egyptair flights crashed suddenly in nearly the same location, without any communication from the pilots indicating anything was amiss. The TWA flight exploded in mid-air. The Egyptair flight apparently did not explode, but went into a sudden and catastrophic dive. During the 36 seconds in which the plane plunged 20,000 feet, the pilots said nothing to ground control.

While the American media has been relatively restrained about the disaster—taking its cue from the Clinton administration and the FBI—the Egyptian and European press carried numerous reports suggesting possible causes for the crash.

Egyptian press suggested peculiar weather conditions in the region, noting that the Egyptair jet crashed very close to the site of the crashes of TWA Flight 800 and the private plane piloted by John F. Kennedy Jr. Egyptian President Hosni Mubarak, a close ally of the US government, said that the two accidents in the same area make him question whether or not the air routes should be changed.

"There may be something in the atmosphere or weather conditions may be sometimes very tough there," he said. "So I think it should be investigated by the United States and if it is needed to change the routes, the airways, depending on the discussions and the assessment of the situation in this part of the world."

The editor-in-chief of Al-Gomhuriya newspaper, Samir Ragab, a confidant of Mubarak, wrote that Washington should investigate suggestions that a US missile test may have caused the TWA disaster. The US authorities should "wake up and reveal the secret of these two disasters which happened in the same place," he said. "There have been persistent reports that the TWA plane exploded because of a missile mistakenly fired from a land base."

Reuters news agency reported that 30 Egyptian military officers who had been receiving training in the United States were on board the flight, including several as high-ranking as brigadier general. Several were pilots training on US-supplied Apache attack helicopters. The Egyptian government has forbidden the country's newspapers to report the presence of the officers on the doomed plane, suggesting that it has something to hide.

Reuters added, citing "aviation sources," that three of the Egyptian officers had not been checked in on the passenger manifest. This explains the discrepancy in the number of victims, which press reports have given variously as 214 and 217. Television reports Sunday morning, later denied by US officials, said that the Egyptair flight, which began in Los Angeles, had made an unscheduled stop at Edwards Air Force Base, in the Mojave Desert outside the city, before proceeding on to New York.

This report, and the Egyptian censorship, raises a number of possibilities—that the plane was targeted for attack because of the large number of military officers on board, or that military equipment or supplies may have been brought on board with them and played a role in the disaster. The 767 jet had stopped at Cairo, Newark, Los Angeles and Kennedy Airport during the 48 hours prior to its destruction.

Another curious aspect of the tragedy is that the 767 which crashed Sunday came off the assembly line at the Everett, Washington plant in the fall of 1989 just before another 767, built for the Austrian airline Lauda, which crashed in 1991 in Thailand. The Lauda jet plummeted to earth catastrophically when its reverse thrusters, used to slow the plane for landing, suddenly and unexpectedly became activated. Some 223 people died in that crash. The two jets are the only 767s to suffer catastrophic mechanical failure, out of more than 750 in service.

The Everett plant was working such heavy overtime during 1989 that it produced widespread complaints from rank-and-file machinists, ultimately sparking a 48-day strike which began October 4, 1989. The Egyptair jet was delivered September 26, 1989, the 282nd to be built, and the Lauda jet followed on October 16, 1989, the 283rd, with work completed by nonunion personnel after the strike began.

Bill Johnson, president of the International Association of Machinists and Aerospace Workers local at the Everett plant, defended the company against the suggestion that heavy overtime had contributed to the disasters. He said it was ''highly improbable'' that stress on workers had led to faulty construction. "You can be assured that when that plane goes out the door it is of the utmost quality that the flying public expects,'' Johnson told the press.

In a grisly irony, the Egyptair tragedy came less than two days after it was revealed that Boeing had concealed from NTSB officials investigating the TWA Flight 800 crash a report which shows that the aircraft manufacturer was well aware of the dangers of a fuel tank explosion in its 747 jets.

NTSB officials revealed October 29 that Boeing had failed to turn over a four-volume report on the dangers of fuel-tank vapors exploding in the military equivalent of the 747, the E-4B. They said that if the report, drafted in 1980, had been provided to them, the information would have directed them immediately to the center fuel tank as the likely cause of the explosion.

As it was, NTSB and FBI investigators clashed repeatedly over 16 months, with the FBI insisting that the explosion was the result of terrorism, before the preliminary conclusion was drawn that a fuel tank explosion was the likely cause. Federal officials learned of the report's existence in March 1999, and the four volumes were not turned over to the NTSB until June.

In the TWA investigation, Boeing officials sided with the FBI suspicions of sabotage, saying that there was no way that the central fuel tank could get hot enough to create the conditions for an explosion. But the 1980 report focused on the danger that excess heat from air conditioners located next to the center fuel tank could create highly flammable fuel vapors inside it. The company recommended that the Air Force add insulation between the air conditioning bay and the fuel tank, the same recommendation made by the NTSB—19 years later!—as part of its investigation into the TWA disaster.

Senator Charles Grassley, a conservative Republican from Iowa who heads the subcommittee reviewing the TWA investigation, said the report should had been released in 1990, after a Philippines Airline Boeing 737 suffered a fuel-tank explosion in Manila. If Boeing had done so, he said, the Flight 800 tragedy could have been averted. "If the NTSB had been given the 1980 report and others, it could have pressed the FAA to set the very standards finally proposed this week for airplane fuel tanks."