ONE SMALL STEP CLOSER

By ELIZABETH GLEICK

As much as Americans desire instant gratification, officials handling the investigation into the crash of TWA Flight 800 see no reason to satisfy that craving. Confirming last week the discovery of microscopic traces of PETN, or pentaerythritol tetranitrate, on a piece of the plane's midsection, investigators moved one step closer to declaring that a bomb or a missile brought down the aircraft. But they caution that there are still many steps to go. A senior Justice Department official told TIME that the PETN, which is used in plastic explosives, is so far the only piece of forensic evidence the investigators have of a possible bomb. They have not found physical evidence of an explosion on any of the metal fragments recovered. Nor have they found any residue of other chemicals they would expect to see if there had been a bomb. The official adds that investigators are still considering innocent explanations for the presence of the petn: the tiny trace could, for example, have come from the bag or boot of a person aboard the plane who had worked with the explosives. Investigators also insist that they have not ruled out mechanical failure as a possibility and have sent portions of the plane to NASA experts who handled the Challenger explosion for further study.

Declaring the crash to be the result of a criminal act will not bring closure; it will only deepen the mystery of who could have done such a thing. It will also allow the legal wrangling to begin. Aviation disaster lawyers say that if investigators cannot determine the precise cause of the crash, victims' families will be unable to collect more than the $75,000 maximum liability permitted under Warsaw Convention rules governing air travel. A finding of mechanical failure would open the way to much larger settlements, as would solid evidence of a bombing--if lawyers can then prove that TWA's security measures were lax. The 225 families that settled with Pan Am over the Lockerbie disaster, for example, collected some $500 million with such a claim. In this case, as in the Pan Am case, it is increasingly clear that any such resolution will be a long time coming.

--By Elizabeth Gleick. Reported by Elaine Rivera/New York and Douglas Waller/Washington

With reporting by ELAINE RIVERA/NEW YORK AND DOUGLAS WALLER/WASHINGTON