Flight Data Recorders

Missing Evidence About the September 11th Flights

Flight data recorders (FDRs) record the readings of instruments and positions of the aircraft's control surfaces over time. They are contained in black boxes that are designed to survive the worst crashes and, like the cockpit voice recorders, are recovered after crashes in order to reconstruct events.

To date, none of the contents of any of the FDRs from the four jetliners commandeered on 9/11/01 have been made public.

Flight Data Recorder Time recorded 25 hour continuous Number of parameters 18 - 1000+ Impact tolerance 3400Gs / 6.5 ms Fire resistance 1100 degC / 30 min Water pressure resistance submerged 20,000 ft Underwater locator beacon 37.5 KHz; battery has shelf life of 6 years or more, with 30-day operation capability upon activation 1

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References

1. Cockpit Voice Recorders (CVR) and Flight Data Recorders (FDR), NTSB.gov,