Sharjah

It was determined that one of the engine failed and caught fire shortly after rotation for unknown reasons. The crew already abandoned a first attempt to takeoff few minutes earlier for similar reasons.

Due to lack of evidences, investigations were unable to determine the exact cause of the accident. It can only be a matter of conjecture as the wreckage was not located. All possible factors were explored, but none appeared plausible. Absence of radio communication between the aircraft and Sharjah after the initial contact and the absence of any distress call might have led to the tentative conclusion that the aircraft had met with a catastrophic disaster while still over the sea. However, the interception of a radio call from the aircraft at about its expected time of arrive at Sharjah and the considerable tailwind on the route seem to indicate the possibility that the aircraft overflew Sharjah under conditions of poor visibility. It is noteworthy that the ETA given by the aircraft as 0642 did not allow for any appreciable tailwind component which was indicated by the evidence of the Heron pilot. Not accounting for this factor could have resulted in the aircraft's descent on its ETA into high ground to the east of Sharjah. It may also explain the inability of Sharjah, to receive any message which may have been transmitted on VHF. However, the NDB at Sharjah was fully operational during the period of the subject flight and should have indicated to the pilot that Sharjah had been overflown unless the ADF system in the aircraft was mishandled or suffered a multiple failure.

The accident resulted from a loss of control of the aircraft by the first officer shortly after taking off on a dark night when instrument flying was necessary. This loss of control was due to the inability of the first officer to fly on instruments. The responsibility for the accident is attributed to the captain for failing to supervise the piloting of the aircraft by the first officer.

The UK Air Ministry considered as improbable that the crash had resulted from sabotage, hostile action or inflight fire. Also considered improbable was complete fuel exhaustion, although the starvation of the supply of gasoline attributed to improper activation of the corresponding controls could not be ruled out. Other possible causes were a bird strike damaging a propeller and leading to the failure of the engine mounting or even an entire wing; some type of structural failure, especially considering the age of aircraft and the history of vibration experienced with the type, or multiple power plant malfunction, which also could have preceded structural failure. Two months after the disappearance, and in following one of the recommendations made in the investigative report, it was announced by the British government that the HP.42 would no longer be used in passenger operations. It was also recommended that commercial aircraft used in long over-water flights be equipped with personal and group life-saving gear, which would later be standard throughout the industry.