Originally Posted by BCR
The fact that the BTS time is different from the FAA time is the problem. The BTS tells us that UA175 took off at 8:23. The Commission using FAA time tells us that UA175 took off at 8:14.
UA93 has the same problem. It took off at 8:28 (BTS) or 8:42 (Commission).
The BTS wheels-off times are generated by ACARS when the wheels leave the runway.
The BTS actual departure times (also called push-back times) are generated by ACARS when the brakes are released and the aircraft moves. Here, the BTS times are the same (or one minute off) the times used by the Commission. That means the ACARS clocks were accurate.
The only attempted explanation for the inconsistency is the implausible idea that Air Traffic Control could have inaccurate clocks. Boston's ATC clock would be nine minutes behind, Newark's ATC clock 14 minutes ahead -- 23 minutes difference.
No official investigation has resolved the discrepancies. The BTS times seem totally ignored. I've started a petition at whitehouse.gov to officially investigate and reconcile the inconsistent times:
It need 150 signatures to even become visible on their petition site.