LONDON -- Jetliners should be made more bomb-resistant to lessen the destructive power of explosions like the one that ripped apart Pan Am Flight 103 over the Scottish town of Lockerbie in December 1988, according to an official report into the disaster yesterday.
Investigators from the British Department of Transport's Air Accidents Investigation Branch called on airplane manufacturers and authorities on airworthiness to work out "measures that might mitigate the effects of explosive devices and improve the tolerance of aircraft structure and systems to explosive damage."
They said that while it would be impossible to neutralize the effects of all bombs, it should be possible to limit the damage to give the pilot a chance of landing the plane with minimum loss of life.
The investigators urged a study to look into modifying existing planes and improving the design of future jetliners to incorporate containment, venting and energy absorption.
A spokesman for the U.S. Civil Aviation Administration said, "We are never going to get an aircraft so strong that it could withstand an explosion of Lockerbie proportions. But we can perhaps design aircraft to withstand smaller explosions so that the plane can fly on and land safely."
A spokesman for Boeing, manufacturers of the 747, said the company would review the recommendations but added, "We believe the only real way to make sure a bomb doesn't destroy an aircraft is to prevent it getting on board to start with."
One of the British proposals "to stimulate thought and discussion" was that blast energy should be channeled to a particular area of the fuselage designed to burst "in a controlled manner" without rupturing other areas of the plane's fuselage and structure.
They also urged improvements to the flight-deck "black box" recorders to enable them to function for a few vital seconds after an explosion and yield crucial evidence.
The black box on the doomed London-New York flight "did not reveal positive evidence of an explosive event," they said.
The investigators called for black boxes from which data would be recoverable after power loss. They also suggested that black boxes should have a backup power supply that could last for a minute.
The recorders should also be able to record "violent positive and negative pressure pulses." A positive pulse would indicate an explosion. A negative pulse would indicate a structural failure.
All 259 people on board Pan Am Flight 103 and 11 residents of Lockerbie died when a high-explosive device hidden in a case in the baggage compartment exploded.
The bodies of 10 passengers were not recovered, and eight of the missing had seats near the wing section. The investigators believe their seats remained attached to the wing that exploded on impact with the ground.
The bomb was 25 inches inboard from the skin of the lower left side of the fuselage when it exploded seven minutes after the plane reached its cruising altitude of 31,000 feet, according to the investigators.
After the explosion tore open the aircraft, they said, the forward fuselage and flight deck area separated from the rest of the plane within two or three seconds of the explosion, hitting one of the engines, breaking it off. Most of the remaining aircraft disintegrated while it was falling nearly straight down from 19,000 feet to 9,000 feet.