|Flowers left by the public on a bridge near the Shoreham air crash site|
Julian Bray writes: It is generally agreed that the Hawker Hunter T7 dual seat 'Cold war' jet, on its run-in towards Shoreham aerodrome (north, along line of the Adur river in line with the airfield runway 20, was flying far, far, too low. It should have been a 500ft minima but most commentators put it at 300-350ft, at its pull-up point.
Pilots generally adopt a minimum of 500ft (just 150metres) above airfield level as a base for any pull-up into a looping manoeuvre, simply as they need to establish height to give a safety margin in case of any error in the calculation of the exit height, at the base of the manoeuvre.
At the risk of upsetting armchair air forum jockeys, we should repeat: "As with all comment has to be treated as pure speculation, but hopefully might spark off additional areas of investigation and enquiry."
Aerobatic displays rely on form and symmetry ie entry and exit levels are ideally at the same height 500ft in =500ft out.
300ft in = 300ft out had the making of what tragically happened at Shoreham....
The grim facts are that coming out of a vertical manoeuvre lower than the entry height possibly unintentionally may have killed more display pilots than other air display accident incidents. It follows that complex set pieces, work better when the safety margins are substantially increased. 500ft being the accepted and mandated minimum.
As higly respected former pilot and industry commentator David Learmont puts it: "Loops, barrel rolls, stall-turns, wing-overs and chandelles are not difficult to perform safely at a high level where there’s lots of room to correct errors. But to carry them out with precision at low level requires tight discipline, and constant monitoring of the aircraft’s pitch and roll rates in conjunction with the rapidly changing airspeed in the climb and descent phases. It is incredibly easy to let the pitch rate – or the pitch-and-roll rate – decay slightly during the descent phase, and that can be terminal. It was for the T7 at Shoreham, whatever the reason."
But there are other important aspects of this flight to consider.
The Hunter had drop-tanks slung beneath its wings. Why were they not removed prior to the display? Possibly as the aircraft has a notoriously short range without them, and would be immediately departing for its next display? Taking the drop tanks off at Shoreham might also have created technical difficulties, re-attaching them for onward flight...who knows? [ According to the later released AAIB Interim report we called this correctly. Both the two wing tanks and the inboard fuel tanks were filled prior to departure from home base]
Why were its flaps deployed throughout? During aerobatic manoeuvres, display pilots have traditionally used this setting although it would be frowned on in 'combat' circles. No one seems to know why, but from a safety point of view has just a marginal bearing.
An observation that has come out of one of the many videos posted to YOUTUBE suggests the pilot had trouble getting this aircraft off its home North Weald runway during take-off. If something had been wrong the experienced Pilot Andy Hills would have declared it 'technical' and returned home.
Finally why did the aircraft crash-land on a dual carriageway packed with slow moving holiday traffic when the pilot seemingly had a choice of veering left away from the A27 ( which is one week on, the A27 still closed and expected to partially re-open on Bank Holiday Monday) and hard landing on the deserted west side of the airfield?
All this suggests the pilot was fully awake and in full command, however a body of opinion suggests the massive G-force of the 'misaligned loop' may have blacked out the pilot, just a few seconds would be enough to set the events at Shoreham in train.
The highly experienced pilot Andy Hills (currently in a medically induced coma) might have regained consciousness, and then realised the grim reality of what was happening. His single task was at that moment to simply save other peoples lives.
Having survived a stall, nose up, losing height and with very little remaining thrust, the wooded copse just outside the airfield perimeter looked to be the final resting place, but low as the plane was it dipped making contact with the roadway slicing off roofs of cars and leaving a flaming debris field 400ft long and some 150ft wide in places.
Perhaps the 'Cold war' jet was falling apart? Not according to the mountain of video being trawled through? Bird strike ? Possible. Flameout? Some video shows (on a single frame ) a flame, or flare. No reheat or afterburner on this particular 1950's jet . Only one special was built, but the Air Ministry bean counters stopped development. BUT did the engine malfunction at that very point on the V/T timeline?
The final moments, one telling screen grab shows the Hawker Hunter skimming traffic only a marginal blur can be seen from the 8ft long tailpipe suggesting it was in effect gliding down to its final resting place. No real power or forward thrust at that point. If it had flamed out on the loop or the jet malfunctioned for any reason, the knock on effect would be the same as played out. Observers say the engine was running throughout, but was it generating sufficient, if any useful thrust?
All questions for the Air Accident Investigation Board. Nothing short of a miracle, the pilot was extracted barely alive, heroically triaged by paramedics on the spot, and then medically air lifted to hospital, 'just holding onto life' was the medical message at the time. Andy Hills now in a medically induced coma. Clearly being positive, when Mr Hills recovers, he can give the best evidence of all, his own recollection.
Vintage jets like this are currently grounded by the CAA pending the Shoreham investigation but if they are cleared and return to the sky remember they still don't have 'black boxes' perhaps they should be legally required to leap forward beyond black box retro kit and go directly for real time satellite digital monitoring? And while they are at it ensure that all passenger aircraft are so fitted, the wiring loom and digi-responder kit is already in place on modern civil aviation jets, but there is no compulsion by airlines to subscribe and pay the subscription charges. It all comes down to money...
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Sources: CAA, BBC, CNS, www.Learmount.com, HH supporters network, and others..
Earlier blog: http://julianbrayrecessionbuster07944217476.blogspot.co.uk/2015/08/hawker-hunter-display-aircraft-crashes.html
Latest blog: http://julianbrayrecessionbuster07944217476.blogspot.com/2015/09/shoreham-air-crash-1st-september-2015.html
JULIAN BRAY +44(0)1733 345581, Journalist, Broadcaster, Aviation Security & Airline Operations Expert, Travel / Maritime & Cruise Industry, EQUITY, NUJ, Broadcast COOBE ISDN ++44 (0)1733 345020 (DUAL CODEC) SKYPE: JULIAN.BRAY.UK e&oe Cell: 07944 217476 or iPhone 0743 530 3145 www.aviationcomment.com # # # VENDOR 10476453 http://feeds.feedburner.com/BraysDuckhouseBlog