Good evening. As you know, this investigation involves many agencies and hundreds, if not thousands, of individuals. But I want to make sure we never forget the 217 persons who lost their lives in this accident. We have families from 18 of the United States and from the Middle East, Europe, South America and Canada who want to know what caused this accident.
To begin our briefing today, I'd like to introduce Rear Admiral William G. Sutton of the United States Navy, who will update us on the cockpit voice recorder recovery effort.
[Admiral Sutton provided a briefing.]
The Flight Data Recorder Group is continuing to work on the data and has captured information that takes us several seconds beyond where we left you at our last briefing and fills in some, but not all, of the gaps we had. We now have less than 5 seconds of data to recover at the end of the recording. I want to re-emphasize for you that this is preliminary data and might be better placed in context by information we hope to learn from the cockpit voice recorder when it is recovered.
As I said on Wednesday, the FDR data appears to end about the same time that the FAA radar stopped receiving the transponder beacon return from the aircraft. As I also stated on Wednesday, the flight appears to have been proceeding normally at about 33,000 feet until the autopilot disconnected. About 8 seconds later, a large nose-down elevator deflection and reduction of power to both engines are recorded. The recorded throttle positions are consistent with this power reduction.
For the next 20 seconds, the airplane was in a zero-G pitch-over with the wings approximately level. A zero-G pitch-over would produce a feeling of weightlessness and result in an increasingly steep flight path.
During this descent, both engine oil pressure indicators switch from "normal" to "low." Boeing documents show that zero-G flight may produce the low pressure, but this is still under active investigation by the FDR group.
At about halfway through this 20-second descent, the speed of the aircraft reaches 0.86 Mach and the Captain's and the First Officer's Master Warnings activate. A Master Warning is one that indicates a potentially major problem with the airplane that the flight crew must attend to immediately.
On this Boeing 767, the Master Warning will activate when:
At this point, the data show a split between the left and right elevator positions.
A few seconds later, FDR parameters "engine start lever", both left and right, changed from "run" to "cut-off." The changes in these and other engine parameters are then consistent with both engines shutting down.
The lowest altitude reached during this descent that is captured by the FDR data we have so far is just below 18,000 feet. Highest speed recorded during the descent is 0.94 Mach.
As you might remember from one of our press conferences last week, radar data indicate that the aircraft climbed back up to about 24,000 feet after descending to about 16,700 feet. As we have only a few seconds of data still to recover at the end of the recording, it would appear that the climb was not recorded by the FDR.
Obviously, these data raise many questions in your minds. I assure you, they raise questions in the minds of the NTSB and the other investigators on this case. We cannot at this time explain the circumstances that were occurring on flight 990 that resulted in the flight profile I just described, and we will not attempt to speculate about it. Further investigation, including information on the cockpit voice recorder, might shed some light on this. Therefore, we will continue to act with the United States Navy to recover the CVR.