Evidence points to wind shear in USAir disaster

July 06, 1994|By New York Times News Service

CHARLOTTE, N.C. -- Shortly after the pilots tried to abort their landing amid torrential rains and gusting winds, USAir Flight 1016 was slammed to earth in a way consistent with what a wind shear would cause, according to a National Transportation Safety Board spokesman.

A board member, John Hammerschmidt, also described to a press briefing last night the desperate efforts of crew members to gain altitude around Saturday. The jet, a DC-9-30, experienced "a severe sink rate" just after it veered to the right and tried to circle Charlotte/Douglas International Airport, Mr. Hammerschmidt said, and crashed, killing 37 people and injuring 20.

Interviews conducted with the pilot and first officer yesterday, along with information from the cockpit voice recorder, tower communications and other data have allowed investigators to put together a chilling chronology of every traveler's worst nightmare: a sudden, vicious storm that kicks up at almost the instant a plane is thundering in for a landing and brings catastrophe.

It will take the safety board nine to 12 months to complete its investigation, and officials stressed that they had not yet determined the cause of the crash. Investigators do not know for sure whether the plane flew into a dangerous wind shear, and if it did, whether the response of the pilot or a mechanical failure might have contributed to the crash.

But Mr. Hammerschmidt said the accident was consistent with wind shear. And investigators are now able to put together an almost second-by-second account of Flight 1016's last two minutes as it roared into a storm.

At a briefing last night, Mr. Hammerschmidt said the captain, John Greenlee, 38, decided to abort the landing after the plane suddenly flew into what he described to investigators as the most rain he had ever seen. The rain kicked up just as he received a wind shear warning from the control tower.

But shortly after he ordered a circle of the airport at maximum power, a "go round," the plane plummeted. At that point, Mr. Greenlee hollered, "Firewall throttles," and he and First Officer 00 James Hayes, 41, who was flying the plane, both pushed their throttles to overthrust settings. But they next heard a warning of an impending stall, heard an alarm system saying "terrain," meaning they were nearing the ground, and then felt three ground impacts, the second one severe.

Although the plane has a wind-shear detection system, the crewmen said they did not recall its going off. But the system only warns that the plane has encountered wind shear, so it is of little use in avoiding wind shear.

Engine performance will be one area to be investigated, but Mr. Hammerschmidt said indications were that both engines were providing power when the accident happened. The crash occurred about 20 seconds after the plane, which weighed 82,225 pounds, began to try to circle the airport. The plane

climbed from 150 feet above the ground to 350 before falling, and reached its maximum power three to four seconds before hitting the ground, he said.

Earlier yesterday, investigators pulled a final body from the wreckage of the tail, which had struck a house near the runway. The discovery did not change the death toll.

The board's investigation will seek to determine the roles played by the weather, the pilots, the equipment, the air-traffic controllers and other factors. Pilots are taught to fly through wind shear, essentially by going into a takeoff altitude with as much power as possible.

But wind shear during a landing can be disastrous, because the wheels and flaps are down, producing drag, and sometimes not even engines operating at full throttle can accelerate the plane quickly enough to keep it airborne. In addition, the most dangerous form of wind shear, a microburst, can be very narrowly localized and thus extremely difficult to detect.

Even if wind shear is found in the crash of Flight 1016, investigators must determine whether the pilots reacted properly it, whether they were given sufficient warning and whether the equipment responded.

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