The Hunter crash - Investigation starts - Curt Lewis

Shoreham airshow crash: the lines of investigation Aviation experts say the Air Accidents Investigation Branch will look at a number of factors in trying to determine what brought down the 1950s fighter Wreckage from the 1950s Hawker Hunter fighter is removed from the scene of the crash Mechanical failure The Air Accidents Investigation Branch team at Farnborough will be looking for signs of engine or instrument failure in the wreckage of the Hawker Hunter. According to Tony Cable, a former AAIB investigator and consultant at Accident and Failure Technical Analysis Ltd, there could still be evidence of what went wrong even after the impact and ground fire. "You might get information of what the control settings were at the time of impact. Was the stick pulled fully back?" he said. The 1950s fighter had no black box or digital data recorder, so the copious amounts of video and photographic evidence from the airshow crowd may prove the best lead. Experts say the age of the aircraft should not have been a factor, assuming it was well maintained, but the restrictions the Civil Aviation Authority introduced on vintage planes this week suggest there are potential concerns. Stephen Wright, a lecturer in aviation at the University of Leeds, said investigators would immediately look at the Hunter's maintenance history. "That becomes the property of the AAIB and is quarantined. That's the baseline, and investigators can work backwards from what happened. What condition the aircraft is in, what's been worked on recently," he said. Mechanical failure was possible, he added: "The AAIB will be trying to establish if the plane was supplying sufficient thrust to complete the manoeuvre. They are designed to turn on a sixpence. The only reason it wouldn't have done so if there was a problem." Pilot error All display pilots have to be licensed and assessed, and follow prepared routines within the level of difficulty to which they have been approved. The pilot in the Shoreham crash, Andy Hill, was vastly experienced, but there have been regular fatalities among those flying at airshows, because they perform difficult and risky manoeuvres. Hill was attempting his stunt at an altitude that left little scope for recovery if he did lose control of the plane. Flight Global's safety editor, David Learmount, said the footage suggested the pilot was trying to lift the plane's nose in the final moments. Bird strike There is no evidence of birds in the footage, but a bird strike remains a possible, if unlikely, factor. Wright said: "It was low altitude. It could ingest a bird. That would flame the engine." One video sequence appears to show a flash from the engines. "That could indicate that part of the engine has detached, a blade has come out." Physical strain Stunt flying and tight turns in fighter jets put the pilot under considerable G-force, and even experienced pilots have been known to black out. A Red Arrows pilot who was killed in crash at the Bournemouth airshow in 2011 was found to have lost consciousness in the seconds before impact. CAA guidance to display pilots also warns of the possibility of visual confusion when flying near the coast, with a "goldfish bowl effect" making it difficult to gauge position accurately. A combination of factors As aviation's comprehensive safety regulations and maintenance checks reduce obvious and known risks, accident reports often identify a sequence of errors or circumstances. Learmount has suggested that a combination of mechanical failure and pilot error could be an explanation "That could have been something in the mechanics or the engine, a twang, that would be tremendously distracting at a point when milliseconds matter.," he said.