This was the third disaster involving a big passenger jet in the area in as many years, and the second to befall a Boeing airliner. In all three crashes, the planes lost power too quickly for the planes to make even emergency landings.
Aviation officials in New York were quick to dampen speculation that a bomb was a likely cause, but disclosed there was a month-old threat that a bomb would "soon" be used on a flight departing from Los Angeles or New York. There was also a report that one passenger booked through to Cairo had left the aircraft at John F Kennedy airport, but this was not confirmed.
Early reports said that the plane fell from 33,000 feet after disappearing off radar screens at around 2am local time (7am GMT). An EgyptAir spokes- man said the pilot made one distress call before all contact was lost.
There were 199 passengers and 15 crew on the plane, 129 of them Americans and 62 Egyptians. The plane was on the final leg of a round-trip journey from Cairo to Los Angeles and back. The crew included four pilots, all of whom had many years of experience.
Debris, including seat cushions and pieces of liferafts, were sighted by a US merchant marine ship about 60 miles south of Nantucket within hours of the plane going missing. The first bodies were recovered soon afterwards.
The route taken by the plane was similar to that of TWA 800, the jumbo jet that crashed off Long Island in 1996 and Swissair 111, the McDonnell Douglas plane that crashed a year ago while trying to make an emergency landing at Halifax, Canada. That flightpath, however, is no different from the one used by hundreds of passenger planes flying from New York across the Atlantic each day.
After more fanciful explanations, such as the coincidence of Hallowe'en or computer confusion generated by the change from summer to winter time, were dismissed, attention focused on the possibility of catastrophic mechanical failure or terrorism. The weather at the time was good.
US officials would not speculate on the likelihood of terrorism, pleading a dearth of information and an absence of any claim of responsibility. An intelligence official said that the possibility was being investigated, but said that "there's nothing to immediately point toward that".
However, the Associated Press reported the existence of an apparent terrorist threat, contained in a Federal Aviation Administration circular on 24 September. It said several US agencies had received a warning in August that a bomb or explosive device with "spiral expansion" would soon be used on a flight departing from either Los Angeles airport or JFK airport, New York.
The circular said the informant identified himself as Luciano Porcari, the same name as a man who hijacked an Iberia Boeing 727 during an internal Spanish flight in 1977, and noted that the device could not be detected by airport metal detectors. EgyptAir said that it had no information about any threat to its planes.
Just two weeks before yesterday's crash, however, an EgyptAir plane flying between Istanbul and Cairo had been hijacked. The plane landed safely in Hamburg, where the hijacker, who was armed with a knife and reported to be mentally disturbed, surrendered.
The plane that went down yesterday had logged 33,000 flight hours - a normal record - since it was acquired by the airline in 1989, and had spent barely an hour on the tarmac at Kennedy airport, after a departure from Los Angeles that was delayed by a tyre-change.
Long criticised as excessively bureaucratic, and infuriatingly inefficient, the 67-year-old EgyptAir history is far from unblemished - despite claims yesterday by Egyptian officials that it has an excellent record, particularly in the past decade.
In 1996, an EgyptAir plane skidded on to a road and rammed into a taxi after landing in Istanbul - a crash that the airline blamed on Turkish airport authorities. A year earlier, an Airbus A300B4 aborted take-off in Cairo, and evacuated passengers after a fire.