Originally Posted by
Lonewolf_50
airtren: ah, visual cues.
What's this supposed to mean?
OK ... but ... if the intent is to climb, where in the sequence is the initial power and pitch change to climb from 350 to 370/375?
Consider: they had recently slowed down to turb air penetration speed. (I presume by using A/P functions).
That is why I asked: do you believe that the nose was used to climb on the assumption that auto throttle would pitch in on time and allow the aircraft to climb at appropriate airspeed/Mach/energy state, rather than by trading airspeed for altitude?
Based on the BEA text, the A/THR was OFF at the time of the climb.
The BEA text does not mention manual power/throttle changes during the climb time interval from FL350 to FL375. So, that makes the climb unintentional?
A kinetic versus potential energy conservation calculation shows that the BEA indicated height delta (2500 ft from FL350 tgo FL375) checks against the BEA indicated delta speed of 60 knots (from 275 to 215 knots). Same is true for FL380, and 185 knots.
dEk = Ek (275knots) - Ek(215knots) = dEp (2500ft)
Originally Posted by PJ2
... One needs an ATC clearance to do so, as one needs an ATC clearance to deviate off course. It is not mentioned in the BEA Update that the crew obtained a clearance either to deviate from course or later, to climb out of FL350.
That's clear. Thanks for the detailed explanation.
But the connecting to Dakar failed, and the contact with the previous ATC was no longer active, so there was no online ATC control/contact at the time.
A deviation of 12 degrees to the left started already prior to to the A/P disconnect, without ATC approval, which would seem to indicate that the PF (and PNF) were already in ATC bypass mode when the climb started...