"Possible turn" at about 18:25?
18:22 Last primary radar contact, aircraft heading NW
18:25 Log-on request initiated from the aircraft terminal
18:28 First 'handshake' arc, BTO and BFO indicate aircraft heading south
Between 18:25 and 18:28 there were 4 exchanges between the ground terminal and the aircraft terminal. The recorded BTO and BFO values for those exchanges varied considerably, which may be attributed to either the non-stabilized operation of the aircraft terminal or the turning of the aircraft. After 18:28 the BTO and BFO values consistently indicate a southern heading, so there must have been a turn after the last radar contact. Between the first and the sixth arc the BTO and BFO values show a steady progression, then there is another 'jump' to the final arc. The final arc is from a log-on request initiated from the aircraft, probably after a power interruption.
EDIT:
The 'jump' between the sixth and the seventh arc may have been due to the airplane descending at the time of the seventh arc.
Last edited by Gysbreght; 8th Jun 2014 at 10:35.