By Zachary D. Roberts
By Anna Merlan
By Jon Campbell and Laura Shunk
By Albert Samaha
By Amanda Dingyuan
By Anna Merlan
By Anna Merlan
By Albert Samaha
At the time, the NTSB countered that the last row of data was from a previous flight, which in another moment, if Flight 800 had continued, would have been erased from the 25-hour-long continuous loop of tape. But to Mann the readouts are simply impossible. "All I can say is, if that was a previous flight, where did it crash?" Mann told the Voice.
But the fact that the data values in the last row make no sense to pilots is not hard for the NTSB to explain. "Since the erasing of the old data happened to end in the middle of a data set, the data readout was garbled for about one second. Therefore, the data you point out is not only 25 flight hours old, but unsynchronized and, thus, meaningless," Goelz of the NTSB told the Voice.
Nevertheless, the FDR data continues to raise more questions than it answers. One industry expert, for instance, agreeing with Donaldson that a sudden decrease in the readouts for airspeed and altitude could be caused by a sudden increase in pressure outside the aircraft, called it "a remarkable coincidence" that garbled data could include results which are consistent for two parameters. The change in other values in the last row--pitch, for instance, which increased from 3.6 to 8.3 degrees, and elevator position, which jumped from 0.1 to 11.2 degrees--could also have been the result of an explosion, although in these cases, the expert noted, the blast could as easily have been internal as external.
Another expert also seemed perplexed by the NTSB's data. When Greg Francois, product manager for data recording equipment for AlliedSignal Air Transport and Regional Avionics, first viewed the FDR report, he told the Voicethat there was clearly more data recorded on the FDR's magnetic tape than is shown in the report. Francois should know what he is talking about: AlliedSignal bought out Sundstrand, which originally developed and manufactured the universal flight data recorder carried on Flight 800. Francois said he was very familiar with the UFDR. Reading through the text of the FDR report written by Dennis Grossi, Francois said that it appeared that during the last half-second of operation the FDR's tape recorded another set of data, which does not appear in the report.
But in a subsequent interview, as the Voicewas going to press, Francois frankly admitted to being puzzled by the report. "I don't know what [the data] means because it's his software--it's how he manipulated the table," he said, referring to Grossi, who did not return a phone message seeking comment on the FDR data.
Donaldson, in any event, is not giving up his smoking gun without a fight. "Every damn bit of data that comes from that airplane fits with a missile burst," he told the Voice.
Critics charge that the NTSB continues to shy away from leads that point to the missile scenario. For instance, the NTSB's Safety Board failed to follow up on tests that it ordered early last year. The reporton those tests, dated May 19, 1997, and yet to be released (albeit obtained by the Voice), indicates that nitrate, a chemical commonly found in explosive compounds, was detected on two pieces from the center fuel tank of TWA Flight 800.
The report says that "splatter-like" samples of material were scraped from a piece of the front spar of the fuel tank, and from an adjacent piece of the tank's upper skin, and sent to NASA's Materials and Chemical Analysis Branch at Kennedy Space Center in Florida for tests. The tests were requested by Dr. Merritt Birky, who heads the NTSB's Fire and Explosions Group.
The lab found minute quantities of nitrate in both samples, which came from pieces designated CW504 and CW114, respectively. CW504, the front spar piece, was the earliest structural piece of the airplane to fall after the initial explosion, and as such has remained a puzzle to NTSB metallurgists trying to explain how the plane broke up. (See the Voice, April 21.)
"An attempt to determine the origin of the anions [nitrate is an anion] present in both samples was not conducted but is of concern and is under further investigation," writes NASA scientist Charles W. Bassett in a concluding comment on the report.
"Just because you find nitrate, it doesn't mean an explosive," Dr. Birky told the Voice. Yet despite agreeing that it was of interest to the NTSB whether the nitrate indicated something innocuous or not, he said, "I don't think we did any further chemical analysis on that splatter."
When asked whether nitrate was found on CW504, NTSB managing director Goelz wrote, in a fax sent last April: "Nitrates were not found on the piece CW504." When the Voicethen faxed him the NASA lab report, he replied that he had misunderstood the earlier question: "I understood your question to be directed at whether there was an explosive device found on TWA Flight 800."
The report is notably absent from an appendix to the NTSB's Fire and Explosions Group chairman's report, which contains several similar lab reports, all done at the same NASA lab. It is also presumably the report referred to in the NTSB's Flight 800 CD-ROM as "CW504 Splatter (not available)."