HSWL, your HS 748 example is not a particularly good one. Without judging crew actions with hindsight – they were the only ones there at the time; there was no evidence to suggest that the aircraft structure would have failed if the engine shut down drills had been completed i.e fuel cocks selected off. With such a catastrophic engine failures, there may be attention getting symptoms that cause a crew to deviate from SOPs, yet if you decide to land straight ahead and hit the airfield boundary ditch with serious consequences, the view of such a decision could be open to severe criticism.
Some regulators / operators who decide to approve drills that delay shut down drills until a safe altitude may not consider or have all of the facts i.e a WAT limited, slow speed turboprop may take 5 mins to reach 1000 ft, let alone 1500 ft.
Most fire drill SOPs are written by the manufacturer and ‘certificating’ authority, however if an operator or ‘operational’ authority changes these without due consideration, all of the good design work if of little use.
I understand that the 400 ft shut down procedure originated from 400 ft being the minimum flap retraction altitude during an engine out procedure.
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Airspeed and Upwardness