BOAC -
- I still do not understand 'inability'? Are you saying that heading information in the RJ100 on both sides would be lost (leaving the standby compass out of this, which is of course, 'able' to provide an approximate heading)? Why could P2 not provide heading info?
No, the Captains EFIS was lost, and the FO's DBI was also lost as this gets its info from IRU1. The FO had a working and correct ND and PFD, and also the standby compass. The standby horizon is clearly visible from the right seat, and can easily be used to cross check indications if there is any doubt. The captain had heading information from his DBI as this takes its feed from IRU2.
It's a shame the CVR wasn't available to the investigation, it would have added a lot of useful information.
With a loss of the FGC (Flight Guidance Computer) and thus the FTC (Flap trim compensator), the RJ becomes a 146 and unless you've flown tbe 146, or practice it regularly in the rj sim, the pitch change when going from flap 0 to flap 18 or vice versus will catch you out. A lot of immediate trim is needed to counteract it. The crew would have been distracted and not prepared for it which could account for the initial "excessive" pitch changes.