Fatal qhestions after the night it rained fire

ARGUABLY and probably by a considerable margin, the most reliable and popular civil airliner of all time, the four-jet Boeing 747 swiftly set new standards of aviation safety and comfort following its entry into commercial service somewhat more than quarter of a century ago.

The 747 (usually known to its operators and airport staff simply as `the 74') also gave a new meaning to the word `Jumbo' on a truly worldwide basis. Since then, despite an immense initial financial risk which could well have bankrupted its manufacturer had the project not been an outstanding success, more than 1000 examples have been sold and dozens of the more modern and unbelievably sophisticated variants remain on order.

Much less well appreciated by the average passenger, but of perhaps even greater importance to the finances of their user airlines, several hundred are operating on inter-continental or transocean routes at any time of the day or night. In turn, they are achieving utilisation rates and a degree of regularity which is still the envy of some of their less successful widebody competitors and their owners.

Despite the passage of more than 26 years, a massive expansion of the 747 fleet, and its growing use by third-world airlines, the Jumbo's accident rate is and remains equally impressive - it appears that only 24 aircraft (this including the TWA machine) have been lost from all causes. This involves a wide and truly global range of incidents, few if any of which have stemmed from actual design-related problems and reflect the utter soundness of the basic design.

As a result, and perhaps uniquely in aviation history, the causes of most Boeing 747 write-offs result from some human failing, either through errors by air crew, maintenance or other personnel.

The most noteworthy examples of these include the world's worst civil aviation accident, on a fog-shrouded Tenerife runway in March 1977 when two Jumbos collided at a horrifying human cost of almost 600 lives.

An improperly-handled repair procedure following an earlier, relatively minor landing incident caused a bulkhead to fail and effectively disable a Japanese machine's tail controls; this resulted in a crash which killed all but four of the 520 occupants in what is the industry's worst single-aircraft crash.

Given the type's high public profile, it inevitably became an attractive terrorist target, with hijacked Jumbos being blown up on the ground after their occupants had been removed and the media were in attendance.

The ultimate manifestation of this twisted and obscene activity, the pre-Christmas 1988 Lockerbie bombing officially remains unresolved and, given the political accommodations and considerations involved when ascribing guilt in this particular case, many within the airline industry suspect it will remain so.

Given the lack of any real evidential detail surrounding the crash of TWA 800, speculation was inevitably rife within a few hours of the tragedy. From what has emerged, the optional causes appear to include, and in no order of probability, (a) a collision with another aircraft, this in turn being seen as ``possible but pretty unlikely'', (b) a bomb, which in the current security climate appears to be a strong candidate, (c) some kind of eventually-catastrophic structural failure which would appear to be a possibility at least, (d) a similarly-lethal engine-related problem also worthy of consideration at this stage.

Should sabotage be involved, as many analysts seem to expect, then searching questions will necessarily be asked about international airport security in its manifold aspects.

Also, and given the recently-announced development by Farnborough specialists of a bomb-proof cargo-hold facility, there will be strong pressure for the system's early availability.

Even relatively minor structural failure could readily have spread throughout the fuselage and caused a massive fuel spillage into the atmosphere; ignition of the enormously volatile mixture might then have come from either the engines or sparks caused by metal to metal contact.

This may also have been a consequence of a massive problem with any of the machine's normally-reliable Pratt & Whitney turbofans, although an alternative to this scenario may have been a major disruption of the adjacent hydraulic systems leading to a loss of control and a near-instantaneous break-up of the airframe.

The answer to these necessarily basic premises lies more than 100ft down on the muddy bed of the Atlantic Ocean and, while the only saving grace is that this at least makes the site relatively accessible, it adds significantly to the pressures increasingly imposed on those charged with identifying an early resolution of this tragedy.