The data has already been interpreted using the Data Frame Layout as follows:
A/C NUMBER appears several times because each bit is listed as a separate parameter. LSB means least significant bit, LSB + 1 means second least significant bit, LSB + 2 means third least significant bit etc. MSB means most significant bit. As you may know, a bit can be one of two values 0 or 1. For the A/C NUMBER we have:
A/C NUMBER LSB = 1
A/C NUMBER LSB + 1 = 1
A/C NUMBER LSB + 2 = 0
A/C NUMBER LSB + 3 = 0
A/C NUMBER LSB + 4 = 0
A/C NUMBER LSB + 5 = 1
A/C NUMBER LSB + 6 = 0
A/C NUMBER MSB = 0
Combining these bits in order with the MSB on the left and the LSB on the right gives 00100011. Converting this number from binary to decimal gives 35.
You may have guessed that this file has been provided by the NTSB, reportedly from AA77 which crashed into the Pentagon. My interest is that there are people who argue that this file is not authentic. If the explantion of the decoding above is correct the numbers 35 and 1 will not be in doubt. What some people dispute is that the numbers 35 and 1 confirm that this is the right aircraft. Is there a way to confirm the identification?
Last edited by gravity32; 1st July 2011 at 04:49.