Because of the aircraft's age, it was not fitted with a flight recorder. Instead, investigators will have to use other methods such as instrument checks.
Five bodies were recovered from the wreckage near the crash site at the south end of Loch Loch near Beinn a' Ghlo, Tayside, and yesterday police and mountain rescue teams were continuing the 'grim task' of searching for the remaining four.
Initial inspections revealed that the remains of the aircraft were contained in a compact area roughly 200 metres square. According to an RAF spokesman, this probably indicated that the aircaft had not exploded in mid-flight but had been destroyed when it hit the ground.
The Hercules was one of three aircraft from RAF Lyneham in Wiltshire, flying north to RAF Lossiemouth on a routine training flight. The Hercules normally has an operational crew of five. The RAF did not explain why an additional four people were on board.
Flt Lt John Sefton from RAF Pitreavie, which is co-ordinating the search operation, described the task facing investigators as a 'Sherlock Holmes operation'. He said the safety record of the Hercules was good. It is 20 years since a Hercules was involved in a crash. Only five have been lost in 26 years of service.
The Ministry of Defence later released the names of the personnel aboard the crashed Hercules aircraft.
The men, described as 'missing believed killed', are: Sqn Ldr Graham Paul Young, 54, married, from Dorset, pilot; Sqn Ldr Stanley Duncan Muir, 49, married, from Midlothian, navigator; Flt Lt Graham Robert John Southard, 33, married, from south-east London, pilot; Flying Officer Jonathan Huw Owen, 23, single, from Stratford-upon-Avon, pilot; Flt Lt Stephen Paul McNally, 27, married, from Wallasey, navigator; Master Engineer Terence John William Gilmore, 39, married, from Humberside, air engineer; Sgt Craig Thomas Hilliard, 23, single, from Inverness, air load master; Sgt Alan Keith King, 32, married, from Cheshire, engineer, and Lance Corporal Gary Reginald Manning, 23, married, from London, Royal Logistics Corps.