The BAC One-Eleven, G-ASJJ, started the takeoff run from runway 18 and accelerated normally until a bang was heard immediately after takeoff. A captain on the jumpseat (who was supervising the route experience of the co-pilot during the flight), commented that he thought it was the no. 1 engine and advised to close the throttle a little later. The pilot-in-command then closed the throttle and lowered the nose from 12deg to 6deg pitch. The engine was shut down and the airspeed decreased from 140 knots to 115 knots. A forced landing was eventually carried out. PROBABLE CAUSE: “The accident must be attributed to a combination of factors following a compressor bang/surge in no. 2 engine immediately after takeoff and the aircraft crashed because the crew, after fully closing no. 1 throttle in error, failed to recognise their mistake and, in addition, were not aware that the thrust of no. 2 engine had also been partially reduced after an inadvertent displacement of the relevant throttle lever.”