Jet 'jigsaw' still puzzles investigators team

TWA crash: Search goes on for vital last piece of evidence amid reports that team may be split over causes of disaster

Investigators believe two separate explosions doomed TWA Flight 800 and are searching for a tell-all "fingerprint" that will determine whether the first blast was caused by a bomb in the passenger cabin.

Federal officials were yesterday speeding up efforts to reassemble wreckage of the plane in the main hangar of a Long Island airfield not far from where it fell to the ocean in a fireball on 17 July, killing all 230 on board. The work, which involves rebuilding the aircraft around a skeleton of chicken wire, is focusing on the section where the wings joined the fuselage, where the worst damage has been found. The pattern of debris on the ocean floor also indicates that parts of the plane's underbelly beneath the wing junction fell to the sea first.

Evidence has also been found suggesting one of the explosions was in the fuel tank between the wings, which was almost empty at the flight's outset. Sources have reported that that blast may have occurred up to 20 seconds after an earlier explosion elsewhere in the aircraft.

That finding, if proved, militates against an earlier theory that an electrical spark may have ignited the fuel tank, causing the initial blast that downed the airliner. Thus investigators are again being drawn to the theory that a primary explosion, which may have triggered the tank blast, was caused by a bomb. In the absence of forensic evidence of an incendiary explosion, the two other primary theories remain under consideration: mechanical failure or a missile attack.

As to where a bomb may have been planted, wreckage retrieved this week clouded two earlier theories: that a detonation occurred in the front cargo hold, where passenger bags were stowed, or in the cockpit. Both scenarios had been fed by evidence that the front of the aircraft was severed from the rest of the fuselage. Items from the hold and the cockpit have meant both areas have been more or less ruled out.

Discovery of fire damage in an area near where the leading edge of the right wing joined the plane has propelled new theories to the fore: that a bomb may have been placed in that area of the cabin, above the fuel tank, in a food trolley or inside a carry-on bag. The inside-right engine also appears to have suffered much greater damage than the other three.

The "fingerprint" that forensic evidence might supply is so far eluding investigators. Preliminary testing by equipment at the hangar this week showed residue of PETN, a prime ingredient of an explosive known as detasheet or detcord and which can also be used in Semtex. But subsequent testing in Washington DC failed to confirm the presence of PETN.

With it being possible that all the hoped-for evidence may have been washed away - about 50 per cent of the plane has been retrieved - investigators are also looking for clues from the directions in which the metal was twisted as well as the pattern of metal fragments in the bodies of passengers.

Shards have been found in passengers' feet and legs, pointing to a blast from below, presumably from the fuel tank. But the extent of damage in that area suggests an explosion there was not sufficient to cripple the plane so decisively.

There may be divisions in the investigation team as it approaches the one-month anniversary of the crash with no clear evidence of what happened that can be offered to the public. A source told the Associated Press news agency: "Investigators are split. Some believe there was an explosion in the forward part of the aircraft. As much as 20 seconds later the fuel tank blew up ... Others speculate that the tank may have been part of the initial blast."

The possibility of a missile attack is thought unlikely. It would almost certainly have been heat-seeking and therefore made initial contact with an engine as it roared to raise the plane to cruising altitude. All four engines have been located and none shows evidence of having been hit. The discovery of the engines has so far provided no evidence of mechanical mishap, including the possibility that one became unhinged.

Three theories on how airliner was downed

1

Mechanical failure

The near-perfect safety record of the Boeing 747 has discouraged investigators from seeing mechanical failure as a likely cause.

Scenarios for such a calamity have also, one by one, been ruled out by what they have found.

The cockpit voice recorders or black boxes, which showed a routine ascent and ended abruptly with a brief, unexplained noise, weigh against pilot error.

The possibility that an engine became unhinged and spun into the rest of the plane is seen as unlikely, since all four engines have been found in reasonable condition.

Suggestions that an electrical spark might have ignited vapour in the central fuel tank have also been discounted. While parts of the tank show fire and smoke damage, other parts appear in pristine condition.

It is now thought the tank may have ignited 20 seconds after an initial blast elsewhere on the plane.

Officials have spoken little about a further possibility: that the plane may have been torn apart by a catastrophic deployment after take-off of the engines' reverse thrusters.

2

Missile

attack

A favourite theory of anyone familiar with the 1990 novel Stinger. Written by Doug Hornig, the book opens with the downing of an American airliner taking off from Boston by a man on a boat with a shoulder-launched Stinger missile.

This scenario was lent early credence by eyewitness sightings of an "object" streaking towards TWA800 just before it exploded as well as by an unexplained second blip on traffic-control radar stills.

A missile attack has been all but ruled out by investigators since the discovery of the fourth engine this week, however.

A missile would almost certainly have been guided by a heat-seeking system and initial contact would have been on an engine. All four have shown damage consistent only with impact on the ocean surface in the crash. Nor, so far, have forensic scientists found any evidence of an incendiary blast on the engines.

And a missile strike would not easily explain the instant loss of electrical power shown by the data and voice tapes. Forensic tests are still continuing.

3

Bomb placed on board

Investigators want to believe a bomb doomed the aircraft after decapitating its front section. But nothing has surfaced yet to provide them with conclusive evidence.

An early theory that a bomb may have been detonated inside passenger luggage stowed in steel cargo containers in the front cargo hold was dashed after all the containers were retrieved and found to be in "unremarkable" condition.

Suspicions about a cooler containing corneas placed in the cockpit just before departure were also negated by the discovery of some undamaged glass covers from cockpit instrumentation. The focus now is on the section where the forward edge of the wings joined the fuselage.

The shape of retrieved plane parts suggests two blasts, one that sent its force downwards from the cabin and another that came from below.

Forensic tests at the hangar where the plane is being reassembled showed initial signs of the presence of PETN, the chief ingredient of a plastic explosive known as detasheet or detcord.

But subsequent and much more reliable tests of the same wreckage parts conducted in Washington DC have failed to confirm these first results.

Suggested Topics
Arts and Entertainment
The first film introduced Daniel Radcliffe to our screens, pictured here as he prepares to board the train to Hogwarts for the first time.
booksHow reading Harry Potter helps children grow up to be gay-friendly
Sport
Frank Lampard will pass Billy Wright and equal Bobby Charton’s caps tally of 106 caps against
sportFormer Chelsea midfielder in Etihad stopgap before New York contract
Arts and Entertainment
A scene from Aladdin is performed at the Tony Awards in New York in June
theatreBrit producer Lythgoe makes kids' musical comedy a Los Angeles hit
Sport
Usain Bolt of Jamaica smiles and shakes hands with a competitor after Jamaica won their first heat in the men's 4x100m relay
sport
PROMOTED VIDEO
Have you tried new the Independent Digital Edition apps?
News
ebookA unique anthology of reporting and analysis of a crucial period of history
News
Chancellor George Osborne, along with the Prime Minister, have been 'complacently claiming the economy is now fixed', according to shadow Chancellor Ed Balls
i100... which is awkward, because he is their boss, after all
News
i100
Arts and Entertainment
Adèle Exarchopoulos and Léa Seydoux play teeneage lovers in the French erotic drama 'Blue Is The Warmest Colour' - The survey found four times as many women admitting to same-sex experiences than 20 years ago
filmBlue Is The Warmest Colour, Bojack Horseman and Hobbit on the way
News
Kenny Ireland, pictured in 2010.
peopleBenidorm actor was just 68
Arts and Entertainment
Preparations begin for Edinburgh Festival 2014
Edinburgh festivalAll the best shows to see at Edinburgh this year
Independent
Travel Shop
the manor
Up to 70% off luxury travel
on city breaks Find out more
santorini
Up to 70% off luxury travel
on chic beach resorts Find out more
sardina foodie
Up to 70% off luxury travel
on country retreats Find out more
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

(Senior) IT Support Engineer - 1st-3rd Line Support

£40000 per annum: Ashdown Group: A successful IT service provider that has bee...

Wind Farm Civil Design Engineer

£55000 - £65000 Per Annum: The Green Recruitment Company: The Green Recruitmen...

Principal Marine Mechanical Engineer

£60000 - £70000 Per Annum: The Green Recruitment Company: The Green Recruitmen...

Principle Geotechnical Engineer

£55000 - £65000 Per Annum: The Green Recruitment Company: The Green Recruitmen...

Day In a Page

Dress the Gaza situation up all you like, but the truth hurts

Robert Fisk on Gaza conflict

Dress the situation up all you like, but the truth hurts
Save the tiger: Tiger, tiger burning less brightly as numbers plummet

Tiger, tiger burning less brightly

When William Blake wrote his famous poem there were probably more than 100,000 tigers in the wild. These days they probably number around 3,200
5 News's Andy Bell retraces his grandfather's steps on the First World War battlefields

In grandfather's footsteps

5 News's political editor Andy Bell only knows his grandfather from the compelling diary he kept during WWI. But when he returned to the killing fields where Edwin Vaughan suffered so much, his ancestor came to life
Lifestyle guru Martha Stewart reveals she has flying robot ... to take photos of her farm

Martha Stewart has flying robot

The lifestyle guru used the drone to get a bird's eye view her 153-acre farm in Bedford, New York
Former Labour minister Meg Hillier has demanded 'pootling lanes' for women cyclists

Do women cyclists need 'pootling lanes'?

Simon Usborne (who's more of a hurtler) explains why winning the space race is key to happy riding
A tale of two presidents: George W Bush downs his paintbrush to pen father’s life story

A tale of two presidents

George W Bush downs his paintbrush to pen father’s life story
Restaurateur Mitch Tonks has given the Great Western Pullman dining car a makeover

The dining car makes a comeback

Restaurateur Mitch Tonks has given the Great Western Pullman dining car a makeover
Gallery rage: How are institutions tackling the discomfort of overcrowding this summer?

Gallery rage

How are institutions tackling the discomfort of overcrowding this summer?
Louis van Gaal has £500,000 video surveillance system installed to monitor Manchester United players

Eye on the prize

Louis van Gaal has £500,000 video surveillance system installed to monitor Manchester United players
Women's rugby: Tamara Taylor adds fuel to the ire in quest to land World Cup

Women's rugby

Tamara Taylor adds fuel to the ire in quest to land World Cup
Save the tiger: The day America’s love of backyard tigers led to a horrific bloodbath

The day America’s love of backyard tigers led to a horrific bloodbath

With only six per cent of the US population of these amazing big cats held in zoos, the Zanesville incident in 2011 was inevitable
Samuel Beckett's biographer reveals secrets of the writer's time as a French Resistance spy

How Samuel Beckett became a French Resistance spy

As this year's Samuel Beckett festival opens in Enniskillen, James Knowlson, recalls how the Irish writer risked his life for liberty and narrowly escaped capture by the Gestapo
We will remember them: relatives still honour those who fought in the Great War

We will remember them

Relatives still honour those who fought in the Great War
Star Wars Episode VII is being shot on film - and now Kodak is launching a last-ditch bid to keep celluloid alive

Kodak's last-ditch bid to keep celluloid alive

Director J J Abrams and a few digital refuseniks shoot movies on film. Simon Usborne wonders what the fuss is about
Once stilted and melodramatic, Hollywood is giving acting in video games a makeover

Acting in video games gets a makeover

David Crookes meets two of the genre's most popular voices