Given that they were where they were...
Hi balsa model and awblain,
Reading your posts, a couple of points spring to mind.
(1) Pitch rose through +10 deg at about t -13. No particular significance in +10, but my guess is that, assuming the pilot's eye height was adjusted (using the seat-height adjustment) to the recommended level, the trees would not have been visible through the windshields after that. Also, not many pilots are used to the perspective at that kind of attitude - except on T/O. At t -7 pitch was about +14. Unfortunately I don't have an A320 AWOPS guide to hand, which might help with the relevant geometry.
At about t -8 the co-pilot warned the captain of some pylons ahead. They were very much further away than the trees, so one can assume that either the co-pilot could not see the trees, or that the steep deck-angle caused him to think that the a/c was higher than the treetops.
(2) Some readers may be surprised to learn that at t = 0 (defined as impact) the stick was still not fully back. IIRC, full deflection is 20 degrees. The last recorded stick position was -17 deg (17 deg nose-up command), rising rapidly from -5 deg at about t -3. What happened after that is not recorded, because the power supplies to both the DFDR and CVR were simultaneously cut (by severing of shared conduit).
Between t -9 and t -4, the stick command was between -6 deg and -7 deg, but this was relaxed slightly at t -4, falling to -5 deg.
ALPHA PROTECTION
As mentioned in the BEA report (see previous posts), the flight-control law changes from Normal Law to Alpha Protection (in effect a sub-law of Normal Law) if the angle of attack rises to an arbitrary figure known as alpha-prot. Alpha Prot "law" tries to maintain that angle of attack if the stick is neutral. A higher angle of attack, known as alpha-max, can be achieved with sustained, full back-stick. Alpha-max provides a small margin from the stall (the latter usually defined as alpha-CL-max), and cannot be exceeded. Intermediate angles of attack are commanded acording to the amount of back-stick applied by the pilot.
The BEA report states that, in their configuration (Flaps 3 and L/G):
alpha-prot was 14.5 deg;
alpha-max was 17.5 deg.
At t = 0 ("impact") both pitch and alpha were about +15. The latter represents the apparent discrepancy of about 2.5 deg that Conf_iture has called into question. As stated above, alpha-max can only be achieved by sustained, full back-stick.
Last edited by Chris Scott; 15th Dec 2013 at 19:33.