THE FINAL three minutes of hijacked United Flight 93 are still a mystery more than a year after it crashed in western Pennsylvania - even to grieving relatives who sought comfort in listening to its cockpit tapes in April.
A Daily News investigation has found a roughly three-minute gap between the time the tape goes silent - according to government-prepared transcripts - and the time that top scientists have pinpointed for the crash.
Several leading seismologists agree that Flight 93 crashed last Sept. 11 at 10:06:05 a.m., give or take a couple of seconds. Family members allowed to hear the cockpit voice recorder in Princeton, N.J., last spring were told it stopped just after 10:03.

The FBI and other agencies refused repeated requests to explain the discrepancy