When ATC requested the go-around, which may have been premature, the Captain (PF) was surprised and inadvertently pressed the autothrust disconnect button instead of TOGA, so the aircraft accelerated down the glideslope until the Captain disconnected the autopilot. (Note: this has similarities with an event in Paris with a B777) . Subsequently flap limit speeds were exceeded and the speed reached 287 kt before the thrust levers were moved from the maximum thrust position. Subsequent QRH checklists were not all completed correctly as the crew became confused and overloaded, and the Captain remained manually flying as they were unable to re-engage the autopilot for some time, and some altitude excursions occurred. Contact with ATC was temporarily lost and the aircraft departed from controlled airspace.

While attempting to analyse the situation the crew became convinced that the flap speed exceedance meant that the flaps would no longer extend fully, so they would now need more runway than was available at Newcastle and requested divertsion to Manchester. During this period, the F/O had problems with the FMS navigation; fuel levels became a concern, but again QRH actions were mishandled for various reasons. The aircraft eventualy landed with significant fuel imbalance and below reserves.

A human factors specialist made the following comment about the initial mishandling of the go-around, which triggered the subsequent chain of events:  ‘The Captain was visual with the runway on a coupled ILS final approach, with every expectation of continuing to land. After many times of experiencing this situation the captain’s brain (unconsciously), brings to readiness a motor response to squeeze the right thumb in order to disconnect the A/T, because that is what normally happens at this point – in order to commence visual landing off the approach.

This might also have been consciously anticipated (he was soon intending to do so). In the second after the go-around instruction, the captain is preparing the action and is only consciously aware that he “needs to do something with his thumb”. Unfortunately his thumb is almost certainly covering or touching the right A/T button as well as being unconsciously primed to disengage the A/T. The primed response (disengaging the A/T), is extremely similar to the required response (pushing the GA buttons). Given the physical thumb position and the highly sensitized action of disengaging the A/T with the thumb (due to [contextual] priming), this error was relatively likely to occur….’

If PIcMA had been the SOP,

1) The Captain, as PM and radio communicator when ATC asked them to go around, would have been better placed to establish whether it was actually needed,

2) the F/O as PF might have been startled by the go-around call, but his initial actions would have been more "primed" for it than the Captain was. 

3) the Captain would possibly have been better placed to understand or question the revised go-around suggested by ATC, and to have remained in contact with ATC and within controlled airspace. As it was both he and the F/O became task-saturated.   

4) In all the subsequent events, the Captain's comprehension of the situation was hampered by his need to fly the aircraft himself, which added to his mental workload.  If the Captain had handed control of the aircraft to the F/O once the go-around had been stabilised, he would have been better placed to understand the flap configuration issues and the (actually non-existent) need for a diversion, and the subsequent fuel situation.