New radar data suggests Flight 990 broke up before impact
Experts downplay possibility of thrust reverser malfunction

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November 4, 1999 Web posted at: 10:57 a.m. EDT (1457 GMT)
NEWPORT, Rhode Island (CNN) -- New radar data reveal EgyptAir Flight 990 started to climb after dropping 17,000 feet in a matter of seconds, then entered a fatal plunge, apparently breaking up before it crashed into the sea, killing all 217 aboard, radar experts said.

The Cairo-bound jet plunged into the sea off Massachusetts less than an hour after leaving John F. Kennedy Airport in New York on Sunday.

Investigators had previously said preliminary radar reports showed the plane plummeted directly into the ocean from an altitude of 33,000 feet. But they now believe that the descent was not direct.

"After descending from 33,000 feet to 16,000 feet, the aircraft climbed back to 24,000 feet. The aircraft then entered a rapid descent," National Transportation Safety Board radar specialist John Clark said on Wednesday.

The new data show numerous "primaries" -- images from the airplane picked up by radar -- in an area northeast of the plane's suspected splashpoint, "moving more consistent with the wind," he said.

That could indicate the plane may, at that stage, have been in the process of breaking up.

Seas too rough for recovery

Vessels combing the ocean off Massachusetts on Wednesday for data recorders from the aircraft suspended their search because of bad weather -- and were not expected to resume work until early next week, crash investigators said.

Winds gusting at 35 mph and waves up to 22 feet have delayed efforts to recover the cockpit voice and flight data recorders. They could provide crucial clues as to what caused the Boeing 767-300 to plummet from the sky.

"It is unclear at this time when we will be able to resume work," NTSB Chairman Jim Hall told reporters.

U.S. Navy Capt. Bert Marsh said seas would probably remain heavy throughout the weekend.

The search has centered about 50 miles southeast of Nantucket Island, where "pings," or electronic signals, from the recorders have been detected.

Although the weather was sunny in Newport, Rhode Island, where search operations are based, the rough conditions at sea forced all but one of the recovery ships to stay ashore Wednesday.

Earlier this week, Coast Guard cutters brought their findings, including pieces of the plane's fuselage and one of its tires, to the naval air station at Quonset Point, Rhode Island, across Narragansett Bay from the Newport Navy base.

Thrust reverser deactivated

Officials probing Sunday's crash also were looking into the possibility that a deactivated engine part called a thrust reverser played a role in the disaster. But, according to several aviation experts, that scenario is unlikely.

As investigators waited for the weather to improve, they collected information about whether one of Flight 990's two thrust reversers might have suddenly activated in flight, knocking the jet off course.

A thrust reverser slows a plane on landing by reversing engine air flow.

An EgyptAir executive confirmed that one of the thrust reversers on the 767 had been turned off before the flight left Cairo en route to the United States.

EgyptAir Vice President for Technology, Megid Al-Masri, told CNN that one of Flight 990's thrust reversers was "deactivated" before the flight left Cairo because maintenance crews there found a hydraulic leak in one of the actuators.

The actuators control the thrust reversal system.

Hall said NTSB investigators would be contacting EgyptAir to review maintenance records that might shed some light on the deactivation.

The flight still met regulations for safe flying, U.S. investigators said, because airplanes are allowed to fly with only one operating thrust reverser.

Al-Masri said the "hydraulic leak" problem was not fixed in Cairo because the airline did not have the correct spare parts. But, he added, the airline planned to repair the problem before the 10-day period allowed under normal international aviation practices.

Pilots who flew the plane on earlier legs also reported a flickering light on an air conditioning system. Two tires were replaced at a stop in Los Angeles where Flight 990 turned around and headed for New York to pick up more Cairo- bound passengers.

Malfunction considered unlikely

Several aviation authorities indicated the deactivated engine part probably did not cause the disaster for a number of reasons:

Hall earlier said radar data show that the compass heading of Flight 990 did not change as it dropped straight down toward the ocean, an indication the thrust reverser did not deploy.

Aviation analyst Jim McKenna confirmed that reasoning. He told CNN if a thrust reverser had deployed in flight, the plane would have turned in the direction of the wing on which it was mounted and the heading would have changed.

Essam Ahmed, an EgyptAir captain and former head of the committee in charge of investigating plane accidents, told reporters in Cairo it was unlikely that something went wrong with the plane's thrust reversers. "The fact that the pilot did not issue an alert proves wrong theories that it plunged for this reason," he said.

Niki Lauda, head of the Austrian-based airline Lauda Air, said thrust reversers had been made "fail-safe" after a 1991 crash involving one of his company's planes that rolled off the Boeing assembly line 10 years ago, just after the EgyptAir jet.

In the 1991 crash, 233 people were killed when the Lauda Air 767 slammed into a jungle hilltop in Thailand after its thrust reversers deployed in flight. Boeing then redesigned the mechanism that controls the thrust reverser.

EgyptAir said the plane used for Flight 990 underwent the modification in 1993. "Assuming the (EgyptAir) plane was operated correctly, I can categorically rule out that the thrust reverser will deploy in flight," Lauda said.

Earlier 990 pilot: Plane flew well

The pilot who flew Flight 990 from Los Angeles to New York, where it landed before it took off again and crashed, told a close friend after the crash that "everything was functioning very good" on the aircraft during the trip to Kennedy airport.

A new crew then took over.

Aboubakr El-Tawansy, a Los Angeles-based computer consultant, told CNN that when the earlier pilot, whom he identified as Abdel Fattah Orabi, learned of the crash, "He was shocked."

"Everything was fine except two flat tires which were replaced," El-Tawansy quoted his friend as saying. "He said everything 'was functioning very good,'" El-Tawansy said.

Sources have also told CNN that a pilot who flew the jetliner to Los Angeles had expressed concern about the functioning of reverse thrusters on the aircraft.

But a spokesman for Delta Airlines, which helped perform "routine maintenance" on the jet before it departed Los Angeles for New York, told CNN that, with the exception of a request to replace two tires, "no other maintenance was requested or performed."

The chief executive officer of Boeing, Philip Condit, said Wednesday no commercial jetliner has a better safety record than his company's 767. Condit said travelers can and should fly the 767 with confidence. "If you look at 18 years, we have a total of three crashes," he said. "One was the result of a hijacking, (there was the) Lauda air crash and now the EgyptAir crash. There's no airplane that has a better safety record over that length of time."

Correspondent Susan Candiotti, The Associated Press and Reuters contributed to this report.