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Missing Seconds

"Are Four Seconds Missing From Official Release Of Flight 800's Data Recorder?

Jerry Cimisi
Dan's Papers, September 29, 2000

Article published here by permission of J. Cimisi
Copyright © 2000 Dans Papers, Inc. All rights reserved.


Note from website author: Several private researchers provide proof in this article that the National Transportation Safety Board has not released a crucial four seconds of data near the end of the Flight Data Recorder (FDR) tape. The first line of this missing data was accidently released by the NTSB and is discussed in The Pilot and the NTSB - NTSB Exhibit 10A Addendum 2.   For related analysis of the Flight Data Recorder and further discussion of the accidentally released line of data see The Smoking Gun - The Flight Data Record and Report to the Subcommittee on Aviation on the Crash of TWA Flight 800Read the full report by Glen Schulze which constitutes hard evidence consistent with the fact that the FBI/NTSB are knowingly withholding from the public over 3.000 flight parameter data bits from the end of FL 800. These 3,000 data bits from the last 4 seconds recorded on the FDR tape may well answer the question of what occurred during those last 4 seconds to cause the disintegration of TWA Flight 800.

Further evidence that four seconds of the FDR tape have not been released was found by Glen Schulze when he reported on March 15, 2001 that when FL 800 was stopped at the end of the runway awaiting to start it's take-off roll the FDR recorded altitude reading was alternating between 17 and 22 ft. This is in close agreement with JFK's runway altitude of 27 ft and the resolution of the Fine Altitude sensor of 5 ft. per bit. During the take off according to the CVR transcript as released by the NTSB the pilot in the left seat called for "gear up" at 2019:43 . But, at 2019:43 Data Table No. 1, Latest Revision Dec. 22, 1999, showed the plane's wheels were still in contact with the runway, i.e. the altitude was 12 feet. One second later the altitude still showed 12 feet then increased to 27 feet in the next fraction of a second. Another second later the altitude had increased to 57 feet. Another second later the altitude had increased to 72 feet and then a fraction of a second later to 97 feet. At 2019:47, four seconds after the pilot had issued the command for "gear up", the altitude had risen to 127 ft. The analysis of these findings is that the NTSB times assigned to the FDR Data Table are offset from true agreement to the aircraft's motion and altitude by 3 to 4 seconds. Specifically, the FDR NTSB inferred and assigned times are inflated in time, i.e. at true time 2019:43 the altitude was at 97 or 127 feet ---not at the later and erroneous FDR inferred times of 2019:46 and 2019:47. Thus 3 to 4 seconds were added to the FDR time line in an attempt to conceal the fact that the last 3 to 4 seconds of data from the FDR tape had been deleted from the FDR Data Tables.


In the midst of the continuing controversy over TWA Flight 800, several private researchers are claiming that the National Transportation Safety Board has not released a crucial four seconds of data near the end of the Flight Data Recorder (FDR) tape.

Glen Schulze of Colorado, who has a Bachelor of Science degree in Electrical Engineering from WashingtonUniversity in St. Louis, has been working with digital data since he was in the military in the 1950s at White Sands. He has done a lengthy analysis of the data the NTSB has released in the four years since Flight 800 exploded and contends there are four missing seconds, approximately 3,000 bits of data. Howard Mann of Southold, retired TWA pilot and flight engineer, has come to the same conclusion.

"I was interested immediately in the Flight 800 story," said Schulze. "At the time it happened I was just finishing up court testimony as an expert witness — on the Cockpit Voice Recorder — in a case against the NTSB involving an aircraft accident off of Block Island in 1991. It was a Beech 1900 that had been on a nighttime landing test with three pilots on board. All the pilots had died. The NTSB ruled that the cause had been pilot error. The families contested that ruling, hired lawyers and eventually had a judge rule against the NTSB and agreed with independent findings that an engine had come off the plane.

"At any rate, I went to the Baltimore hearings on 800 at the end of 1997 — and I was at the hearing where they gave the final report this past August in Washington, D.C. It's been apparent to me that there have been a number of things amiss with the investigation, from the FBI not correctly tagging debris at the Calverton hangar to the stories of the eyewitnnesses being brushed aside.

"I remember that soon after the black boxes were found, Kalstrom [FBI agent in charge of the 800 investigation] said that both the Cockpit Voice Recorder and the Flight Data Recorder ended with signals that were not normal. We know there is a 100 millisecond sound that has never been identiffied at the end of the CVR. And in fact tests the NTSB conducted at Bruntingthorpe in England in which an old 747 was exploded, to record the sounds it made, have not been released."

The study of the Flight Data Recorder, which investigators both official and unofficial hoped would yield distinct clues as to the cause of the fate of the plane, is, by its nature, a highly technical study. Numbers that one reads on the NTSB's Flight Data Recorder docket are arrived at through a complex passage. The data is recorded on magnetic tape in sine waves, translated to binary data, then to engineering (base ten) figures.

Schulze turned his expertise to the FDR when data from it was first released at the end of 1997. Debate over the Flight Data Recorder has been a sometimes sensational, if complex aspect of the Flight 800 investigation. Soon after FDR data was first made public at the NTSB Baltimore hearing in December, 1997, retired TWA pilot and flight engineer, Howard Mann of Southold, pointed out that the last line of data (what came to be known as The Twleve Second Line) at 20:31:12 — or twelve seconds after 8:31 p.m. — showed readings that could indicate the airplane had been subjected to a high pressure wave initiated by an explosion that had come from outside the plane. Eventually, the NTSB later removed this line from their website, claiming that that the anomalous readings were actually left over from a previous flight, Flight 803.

The FDR is a 25 hour tape, with current data erasing data 25 hours old. So the end of Flight 800 data would soon be followed (after an erasure gap) on the tape by data from 25 hours previous.

In regards to the current debate over the FDR: A Flordia researcher, Marilyn Brady, arrived at what in retrospect seems an obvious method of keeping track of the sequence of data. The FDR records a set of 43 data words, in sequence, continously throughout the flight. In one second the FDR records 64 words of data — in other words, one complete 43 word set, and then 21 words of a second, repeating set. In two seconds, the FDR would record 128 data words, one data word less than three complete sets of data words (43 x 3 = 129).

Each data word is given a number. The above sequencing means that every two seconds, there is a shift of one in the data word number. For instance, if one second ends in data word 34, two seconds later will end with data word 33; two seconds after that, with data word 32.

In a detailed summary reached after studying the FDR by this method, Howard Mann writes, "The NTSB has supplied data that purports to be from the last second (20:31:11) of the Flight 800 FDR tape but we can tell from the beginning data word 27 that its location indicates the data the NTSB has forwarded to outside investigators could not have been recorded until time 20:31:15."

Schulze related that a big problem with the FDR data is that the times given for the multitude of readings on that tape are timed by synchronizing it with the time on the Cockpit Voice Recorder — even though the FDR does have data words for hours, minutes and seconds.

Schulze said that when he attended the recent final hearing for Flight 800 this past August in Washington, he asked Dennis R. Grossi (who headed the NTSB's FDR study group) why that was so. "His response to me,' said Schulze, was 'Well, we used to publish that but it got us into trouble.'

"I asked him why. He said it was 'too precise. We have to correlate time with the air traffic control, the cockpit voice recorder, the FDR and six radars. If we get within three seconds we think it is the best we can do.'"

In fact, added Schulze, "The Cockpit Voice Recorder has no imbedded time. All you get is voice. The pilot's speech is correlated with the Boston Air Traffic Control tape."

The NTSB might well say that the above is ample reason the agency's report on the FDR has undergone more revisions than any other investigation into the many facets of Flight 800, while critics such as Schulze and Mann contend otherwise. "I think there are four seconds in a drawer somewhere," said Schulze.

Schulze went on to say that no matter what time the NTSB tagged its data with, there obviously have to have been a specific number of data words every second, and in a specific progression.

Howard Mann pointed out that the NTSB, in its own revision to the Flight Data Recorder report, said that the last line of data for Flight 800 occurred at 20:31:11 — eleven seconds after 8:31 p.m.; and the last data word recorded was data word four, which is the reading for the month of the year.

But Mann, through painstaking means, arrived at a different end point. He went back to the first data word recorded for the flight, at 20:18:40 and then, marking the steady progression of data (43 data words in their normal order, repeating three times less one every two seconds), he set down the sequence and times for the entirety of the brief flight — and found that the eleventh line ended with data word six. One would have to progress through the sequence another four seconds, until 20:31:15 for the data to end on word four. This puts in the minds of Mann, Schulze and other researchers the possibility that there are actually four seconds of data the NTSB has not released.

By the NTSB's own admission, when it first processed the information on the Flight Data Recorder, it used an incorrect software program. The Addendum to Group Chairman's Factual Report (Revision 1) stated that the "recovery software used to produce the tabular listing in the original Addendum report was designed to process a standard 64 word, 1 second data frame, not the 43 word, 0.67188 second data frame" in operation on Flight 800.

The sine waves on the magnetic tape of the Flight Data Recorder can be made visible by the application of a fluid. Thus one can see where the data ends. And the magnetic patterns indicate the Flight 800 data ends with word four. At the same time, the NTSB's tabular data ends with word 6. To further complicate matters, the enginneering values (base ten numbers) for the sine waveforms for word four are decoded to equal word six.

Glen Schulze constructed a matrix of data blocks to follow the precession of data words. He called the 43 data words a subframe and the 64 readings a second one data block. The point at which a data word is recorded at the same point relative to the second is a 43 second superframe. Schulze contends that for the FDR to end at data block four this must occur at superframe block 35 "as these two events are mutually exclusive."

He adds, "The earliest and the latest NTSB Flight Parameter Tabular Data Charts No. 1 and No. 2 stop well short of Superframe 17, data block 35," and adds that this indicates data blocks 32, 33, 34 and 35 have been omitted.

At the recent NTSB hearing in Washington, D.C. Dennis R. Grossi was asked to address the concern that four seconds are missing from the FDR data. According to Schulze, who was there, and Mann, who noted it on TV, Grossi talked for ten minutes or so, discussing the FDR data interpretation in general, but never addressed the possibility of the missing four seconds.

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