The Shoreham Hunter crash unravelled

A lot of misleading comment about the 22 August Shoreham air show crash has already been written. Here’s an attempt to put the event into context.

First, these are some topical issues surrounding the short aerobatic flight by the Hawker Hunter T7.

It’s clear that when this Hunter was on its run-in towards Shoreham aerodrome from the north, following the Adur river valley in line with the airfield’s runway 20, it was very low. My estimate is 300ft or even less as it approached its pull-up point close to the airfield boundary, and other experienced aerobatic pilots say it was lower still.

Most pilots would choose – or be ordered to adopt – a minimum of 500ft above airfield level as a base for their pull-up into a looping manoeuvre, because they need that height to give them room for error in judging the exit height at the base of the manoeuvre.

Five hundred feet (150m) is not high – it does not give spectators a crick in their necks to watch the aircraft pass at that height. It only allows a small margin for height error when exiting from vertical manoeuvres. But 300ft or lower at entry provides even less.

A pilot intending to carry out a vertical manoeuvre like aerobatic looping – or simultaneous looping-and-rolling as in a barrel roll – normally aims to complete it at the same height he enters it. As well as being common sense, that makes it look precise and disciplined to spectators.

Coming out of a vertical manoeuvre lower than the entry height – unintentionally – has probably killed more display pilots than any other single category of air display accident. 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.

Meanwhile there have been actual criticisms from pilots of several other aspects of the conduct of this flight.

The Hunter had drop-tanks beneath its wings. These are fuel tanks that are used when the aircraft needs to extend its range or airborne endurance, and are ideally removed for aerobatic displays because the aircraft is then lighter and has less aerodynamic drag. But the existence of these drop tanks, empty of fuel, would not have been the cause of this accident.

The aircraft also could be seen to have flaps deployed during all – or most – of its short sortie. This low flap-setting is used at take-off, and can be used when airborne to tighten the aircraft’s turning radius in combat, but at the cost of increasing drag considerably and thus reducing speed. A former RAF Hunter pilot I know well told me he would not have used any flap for the manoeuvres we watched, but he agreed that flap deployment would not, alone, have been a cause for this accident. But other Hunter pilots have posted on the Professional Pilots’ Rumour Network that flap was commonly used in aerobatic manoeuvres, including by the Black Arrows, the predecessors to the Red Arrows.

An observation that has come out of a video released today suggests the pilot had trouble getting this aircraft off the runway at take-off. The video shows the ill-fated aircraft carrying out a very long take-off run, lifting off right at the far end of the runway at its North Weald base and then staying low before climbing away. It has been suggested that the aircraft’s engine was under-performing.

If there had been something wrong with the engine, especially in a single-engine aircraft like this, no pilot would continue the flight, especially into an aerobatic sequence.

It’s a common tactic for display pilots to hold the aircraft on the runway for a little longer than necessary during take-off, and then hold it low above the runway for a while after unstick, so the aircraft accelerates more rapidly and can then be manoeuvred more dramatically for crowd-pleasing purposes.

It’s also worth remembering that the Hunter may have been a fast and agile aircraft for its time, but is not a patch on modern jets like the Typhoon and Tornado. It’s a 1950s aeroplane with a single, un-reheated Rolls-Royce Avon jet engine. It does NOT have the afterburner engines that can power a jet vertically into the sky.

Aeroplanes like the Hunter need empathetic pilots to get the best performance out of them, because the brute force of a modern jet engine is not there to get them out of trouble when they need it.

More than any other factor in this accident, the puzzle for me is why the aircraft crash-landed on the busy main road when the pilot – if he was conscious – seemed to have had a choice of veering left from that fatal descent toward the A27 and landing on the west side of the airfield, if not the runway itself (the spectators were on the runway’s east side).

On its final approach toward the road the aircraft was descending steeply out of a looping manoeuvre, so it should have had sufficient speed to bank safely to the left and head for the open grass of the airfield. It would only have required a turn left through about 45deg to have lined up parallel to the runway.

That presupposes the pilot was fully conscious and there was nothing else wrong with the aircraft. In 2011 one of the Red Arrow pilots suffered G-induced loss of consciousness during a high speed, high-G turn close to the ground, and crashed fatally.

Was something wrong with the aircraft? In the video footage, nothing is seen falling off it, no puffs of smoke from the engine, and in some footage of the aircraft’s last moments there is visible heat haze behind the engine jetpipe, and engine noise could clearly be heard, suggesting the engine was at least running even if not generating full power.

But in a video released later there appear to be a couple of visible flashes near the aircraft just before the apex of the looping manoeuvre, when the aircraft was completely inverted. But there were no associated bangs, the engine noise was unchanged, and the flashes did not show on any other videos of the same sector.

The pilot, if he suspected engine trouble, would have had the option of rolling upright and abandoning the display. The fact he didn’t suggests he saw no trouble at that point.

It will take all the forensic magic of the Air Accident Investigation Branch to find the answers, because there are no black boxes on an aircraft like this.

 

 

12 thoughts on “The Shoreham Hunter crash unravelled

  1. With fuel in the 100 gallon drop tanks , the Hunter T7 would need to use most of North Weald`s 02/20 runway length of 1920 metres – especially on a warm day and also on the assumption that the pilot had selected Take- off flap beforehand . As a general rule , Hunter pilots would normally choose runways with a usable length of at least 6000 feet – and preferably with a safety barrier at the end !.

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  2. I wonder whether the drop tanks were full of fuel. This would explain the long take off run due to the extra weight. It might also explain the two distinct black plumes of smoke from the fuel exploding: two drop tanks torn off at fractionally different times and exploding like two napalm bombs. I hope I’m completely wrong.

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  3. could it of had the wrong fuel in some tanks like av gas and not jet fuel,i think jet fuel is more greasee like diesel and perhaps does n,t burn so explosively like av gas petrol.

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  4. Sir Can you sent me your emailadres , so that i can sent you an intresting video , about this accident

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  5. So, according to the interim report, the Hunter was “fully fuelled” including the underwing drop tanks. What sort of utter insanity is this? A ‘plane performing acrobatics (or attempting to) with two bombs under the wings? This should NEVER have been allowed to happen, and those responsible…

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  6. …at this point it seems the pilot started the display at 200 feet, which was illegal (he was only licensed down to 500 feet). These are reportedly facts as stated in the official interim report. Why the pilot started the display at such a dangerously low altitude will be for the full enquiry to attempt to ascertain. The issue of the drop tanks is separate: is it legal for planes to attempt such acrobatics in public displays with not just a full load of internal fuel, but fully fuelled drop tanks too? It cannot be sensible to do so, given weight, drag and – as horrifically and fatally shown – the appalling incremental risks if something goes wrong, as happened on this occasion. If carrying such a lethally large load of fuel in drop tanks in air displays over public roads is legal then IMHO the law needs changing. Surely this is common sense? Anyone seeing those awful fireballs when the Hunter hit the ground causing 11 deaths of completely innocent people would agree. If carrying such a large load of external fuel whilst attempting such acrobatics is already illegal, then why was this plane loaded with so much fuel in the first place? And why isn’t the media focusing on this?

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    • 1. Did the Hunter enter the manoeuvre too low? Well, perhaps, according to some witnesses, such as Captain Brown, who thought so. However, the Hunter would have been flying within the guidelines at its lowest position before entry, some 200ft. It eased into its ascent. It would have entered into the manoeuvre when the pitch was 30%, at which point the aircraft would have been significantly higher than the earlier point of level height. The entry to the manouevre, technically, may well have happened at or beyond 500ft above ground level. In which case the Hunter did not enter the manouevre too low,

      2. Did the Hunter reach the apex of the manoeuvre at sufficient height and speed to safely conclude the quarter clover (if that was what was intended)? The AIIB tell us that the aircraft became ‘ almost fully inverted at the apex of the manoeuvre at a height of approximately 2,600 ft amsl’, There are only witness estimates of the airspeed at present. However, it seems to me that the significant question is not whether the Hunter entered the manoeuvre too low, but whether the Hunter left the apex of the manoeuvre at an appropriate height and speed.

      3. It is clear that something went catastrophically, dreadfully wrong at some point during the manoeuvre, but at which point? I believe that should the pilot have found a problem with the aircraft, or his handling of it, before the apex, then he would have rolled out and aborted. But I think that something happened unexpectedly at or after the apex, which resulted in the terrifying dive, stall, and disaster,

      The full AIIB report will tell us as much as can be told about what happened. Their remit is not to apportion blame, but to prevent future accidents. That report nonetheless will be central to debates of how airshows will be run in the future (should they continue), and will impinge on everyone involved in these events, and in particular on the crew that prepared the Hunter for its fatal flight, the pilot that flew it, and all the others responsible for organising and authorising the Shoreham event.

      It is premature to talk about illegality and guilt: there is no public evidence to support that. Nobody wished for such a disaster, our hearts go out to all those touched by it, and we fervently wish it never happens again.

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    • It is against all advice to display using external tanks. Responsible organisers would have picked up on this.

      It is common to be given free fuel for a display by a sponser and some cheapskates will take advantage. Who knows what motavated these lunatics.

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  7. Richard – an excellent response very clearly put. It may be that the rules as applied to display flying do not in any real world way protect people outside the display area, unless living in an area with a minimum flying height designation. All those killed were outside the airfield boundary and were not officially spectators. I lived in Lancing for 11 years( prior to moving the other side of the river to Shoreham) which is supposed to have a 1000′ minimum height requirement during displays. The Hunter could well have reached the 500′ minimum by the time it passed the 30° point technically meaning that it was only from that point on carrying out an aerobatic manouevre, however, the wisdom of beginning such a manouevre from such a low height, on a hot, presumably humid day, has to be seriously questioned. As had been stated elsewhere, it’s not so much the height of the point of entry, but the height at which it reached its apex that’s most significant. Knowing the area well, my guess from the footage taken from Mill Hill, is that he began the manouevre around 230′ or so, as the aircraft passes below the top of Lancing Hill, from that viewpoint, which is around 280′ high. A significant question would be, where does he usually practise in this aircraft such a manouevre, what is the aspect of the surrounding land, what kinds of weather has he practised in, and how full would the drop tanks be? My opinion right now (which counts for little, as I’m not a pilot, simply an affected resident also stuck in that traffic on that day, just fortunately in the right place displaced both in place and time from the accident), is that in trying to offer a good display to the spectators, and make an entrance from below the spectators eyeline and zoom into the sky, made some serious errors of judgement. Legal aspects will no doubt focus on issues of recklessness and culpability. Interestingly, I was at Ford market today, and saw a policeman apparently scanning/photographing what looks like a Hunter aircraft on the podium outside. Curious what that’s about?

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  8. This accident has saddened me greatly, mainly for the victims and their relatives but also for the thousands of avid aviation buffs who had absolutely no imput whatsoever to the cause of the accident but have been and will continue to be punished by higher costs, cancellations and draconian restrictions to future air shows.
    Having said that here are my credentials, I am a retired Licenced aircraft engineer on wide body jets, I served for fifteen years in the Royal Air Force some of those years on Hunter Squadrons 14 and 19. I am also a past holder of a Private Piloits Licence with One thousand five hundred hours as pilot in command.
    So lets discuss this accident and what led up to it and the aftermath.
    The Hunter is capable of carrying four drop tanks but only the FG 9 and the FR 10 have the two larger tanks slung inboard, these tanks are I believe not jettisonable as they have stabilising struts fitted, those that know please correct me If I am wrong. The F4, F6 and T7 can carry four drop tanks but only do so for long distance ferry flights, usually the aircraft flew permanently with only the inboard drop tanks and I have never ever seen a Hunter returned having jettisonned them. Although I was an engineer in the air force I have had the opportunity to fly in a T7 and directly after reaching a safe height have carried out a series of aerobatics with virtually full fuel tanks although I will concede that added weight coupled with low altitude “will” complicate matters with the results shown at Shoreham.
    The pilot will have taken off allegedly from a short runway at Kemble, he had probably taken off from that same runway safely many times. With a decent wind directly down the runway nothing untoward would have been witnessed. But in a nil wind situation one notch of flaps will have been selected to produce more lift to the wings at a slightly lower unstick speed ie using less runway. Another safety ploy is to hold the nose down to gain speed which will allow the aircraft to accellerate to a safer climb speed.
    Because the pilot had to transit from Kemble to Shoreham most if not all of the fuel in the drop tanks will have been burned off so most of the problems that those tanks would have produced would have been drag and not weight. The Hunter also could not land at Shoreham as the runways are grass and after the display he had to fly onto another airfield for fuel if he did not have enough fuel to get back to Kemble and I am not sure but he might have had to fly to another display venue.
    I have not seen or heard anything technical that has been mentioned that could have been blamed for the crash only out of date cartridges fitted to the ejection seats that have totally no bearing on the situation. If that was the only thing they found and the paperwork although not quite correct the aircraft could have been given extra hours to fly whilst waiting for new cartridges to arrive. The pilot could always refuse to fly if he was not happy with the situation. This all tells me that the aircraft was looked after quite meticulously by an above board company.
    The RAF did however lose a few Hunters due to runaway tail trim motors curiously enough some of those aircraft were lost during air displays. Google Radfan Hunters and read the accident history of the squadrons that operated out there. My thoughts are one unmodified motor might have found itself on the serviceable shelf and eventually onto the aircraft but I do not know whether the investigation team are aware of that particular bit of history of the Hunter.
    Now to the display itself, Every fast jet display pilot flying heavy ten tons plus aircraft near the ground will almost certainly after pulling over the top and with no more than fourty degrees nose down will roll out definitely to avoid the embarrassment of maybe coming too close to the ground or god forbid hitting it, this ploy does not look as spectacular and causes the pilot to fly away from the display line most people would be impressed but there would be a few critics. ALL display pilots are aware of the minimum height for their particular aircraft to start a safe complete loop conversely they know the minimum height they should be at the top of the loop to allow them to pull out at a safe height. Of course there is a way of cheating and that is gaining a lot more than the speed required initially to carry out a normal loop so that the aircraft will zoom climb to the safe height required. I have only seen film of the incident and it appeared to me that it was not a true loop and the aircraft while inverted changed direction which sent it towards the packed duel carriageway. Whether the turn was pilot induced only he will know if he had not blacked out, that leads me to ask, was he wearing a G suit. I know he was a fighter pilot but body tolerances do deplete as we get older so a G suit is essential.
    As a licenced engineer I was heavily involved and had to know the legal limitations that I was controlled by just to release an aircraft for flight but there is one job that I would definitely not do and that is to be an aviation crash inspector, I would hate to have to apportion blame then go on to write new rules that would further curtail other peoples enjoyment of flying and those who just enjoy watching.

    AL.

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