Hello, Chris Scott, OK465, BOAC;
Since AP1 was engaged at the time of the event, and re-engaged subsequent to the recovery I think the PF was the captain. While not strictly SOP, normally a left seat PF engages AP1 and a right seat PF engages AP2.
However, the captain was eating dinner, with the retractable tray out and it is common for the PNF to temporarily take over PF duties as well as communications while the other crew member is having a meal. The AP is left in AP1, again informally.
Where something like this 'interruption in smooth flight' occurs, the "PNF" would continue the PF's duties and mind the store until the PF can put the meal and tray away and resume PF duties to deal with the event.
The Report mentions and describes the incorrect priorities and evident loss of CRM and the "command-control" process as both crew members were fussing with getting the dinner tray onto the observer's seat and getting out the PA handset for an announcement. Even as we don't have the CVR, this is clearly another breakdown in cockpit discipline, placing "Communicate" ahead of "Aviate, & Navigate". Without the CVR we dont' know if control was actually, verbally handed back to the PF, ("You have control....I have control", etc).
Further, it was the PNF's SS instinctive-disconnect button that was pressed and disconnected the AP but he clicked twice on the button which cancels the aural and ECAM warnings. From long observation, pressing the instinctive button to cancel the AP warning is not atypical behaviour; - this would have been out of habit, but here the cancellation robbed the PF of information that the AP had been disconnected and the altitude alert was also missed. The BEA Report states that such cancellation of the warning was an amber AP OFF, (OK465 you know, I do recall an amber "AP OFF" ECAM message somewhere in the dim past (perhaps on the A320?), but I can't find reference to it in either older A340 or recent A330 FCOMs. I can only find "red warnings" reference, (see below). Certainly, under the circumstances of this intentional, by the instinctive button disconnect, the warning was/is always red and the AP cavalry charge continues until the button is pressed again so the BEA Report is incorrect in its reference to the "amber AP OFF" ECAM message.
The PF who was distracted getting his meal put away, was unaware that the AP was disconnected and the airplane was under manual control. The PF remained unaware until he realized that the airplane had climbed well above its cleared altitude and when he went to set the AP to descend to their cleared altitude, did not see "AP" annunciated on the FMA, (p.5 of the Report).
The Report explains the fact that it was the "PNF" who disconnected the AP, but leaves us there as to who was flying once the PNF made the HF call to advise New York Aeradio of the level bust, while the airplane was essentially still out-of-control), nor does the Report explain why the "PNF" chose to disconnect the AP and then do what he did, which was to pitch the airplane up.
The use of airborne radar has been a topic of considerable interest since June 1, 2009 particularly. I have noticed that air carriers began publishing in their FCOMs supplementary notes on the use of current radars including various techniques of using antenna tilt and gain. It's about time.
Given history and the formally recognized need to address certain cultural issues within the carrier*, I would hope that this got a thorough internal review (I wonder if their flight data program picked this up?), because, "If the AP had not been manually disengaged, it would have remained engaged; there would not have been a significant trajectory deviation, with a gain in altitude of about 200 ft.
Note: Without the high angle of attack protection, the aeroplane would have kept its ascending trajectory until the triggering of the stall warning. p.9"
*
Operational Safety Review, Dec, 2009 - the contents of, and I believe, links to this review have been previously reported on PPRuNe.