FlexibleResponse:
But WHAT caused the horizontal stabilizer to be at 13 degrees?
I understand the freezing part but WHAT is just as vital.
rgbrock1,
Sorry, I used the term "freezing" in the English English sense as opposed to American English. I meant to say the stabilizer stopped working automatically and maintained its last position at 13 deg because of the change of flight control law to ABNORMAL ATTITUDE LAW.
The reason the STABILIZER was at 13 degrees was the zoom climb performed by the PF to pull back and climb to 38,000 feet from cruise altitude, which traded the kinetic speed energy at cruise to potential energy of height gain (and consequential speed loss).
The stabilizer happily auto-trimmed more and more nose up during this manoeuvre as speed was rapidly lost until the aircraft sensed at least one of the extreme parameters that activated ABNORMAL FLIGHT LAW. That event stopped the stabilizer where it was at that instant.
From that moment, the fate of AF447 was sealed unless one of the pilots re-trimmed the stabilizer to the NORMAL RANGE range.
What is the NORMAL RANGE?
NORMAL RANGE for STABILIZER
1. Preflight - 4 deg NU
2. Takeoff Range - Approx 4 deg NU
3. Cruise range - 0 to 2 deg NU
MAX RANGE for STABILIZER
1. Maximum NU - 15 deg NU
2. Maximum ND - 4 deg ND
The detail is all from memory and anyone who is current on type should feel free to correct me.