BBF
As the machine was plainly under the control of the pilots
While this was the original opinion of MoD, the Directorate of Air Staffs belatedly admitted in 2005, in writing, that the aircraft may not have been under control, and that the lack of control may only have become evident as they tried to execute the post-waypoint turn (i.e. at the end of a straight leg).
In the same letter they confirmed there was no obligation to be IFR if the pilots intended making that turn.
The above belatedly acknowledged the truth of the evidence Sqn Ldr Burke was prevented from giving to give to the BoI, but later gave to the HoL. In doing so, D/Air Staffs clearly contradicted the many anti-Burke briefings MoD had so vindictively conducted; which is to their credit. (I'm trying to be fair, but it's not actually clear from the letter if they KNEW they were contradicting the party line!).
Perhaps further posts should use this admission as the baseline for discussion, instead of the previous, discredited one.