AAIB investigation to Hawker Hunter T7 G-BXFI 22 August 2015
 

This is a new thread to discus the AAIB report, released on Friday 3rd March 2017.

There are other threads on pprune discussing the crash, the aftermath and display authority issues.

This thread is to discuss the actions and recommendations of the AAIB in relation to this incident.

Recommend reading the entire report before taking the media's word for it; they don't have a particularly good record when it comes to aviation reporting. At over 400 pages, I suspect they have just read the summary so far.

Too low, too slow. Didn't roll out of the manouvre when he might have done.

Knew this about two hours after the event didn't we?

Not had time to read all of it it yet, but one key point made "was that the pilot was not trained in or had not practiced the escape manoeuvre".

Am I missing something here, because the escape manoeuvre is simply to roll upright at the top, or very shortly after the top, and fly away when it is obvious there is insufficient height and/or speed to complete the loop.

We learned the "roll off the top" aero very early in our RAF training.

TBH, there is absolutely no need for the vast majority of interested aviators (and ex aviators) to read "the entire report".

Anyone who cannot deduct the general flight safety lessons from the summary and conclusions of this accident report should not hold a pilots licence, as they don't have the necessary mindset/effective intelligence to be in command in the air, in anything other than perhaps a hot air balloon (no offence meant to balloonists).

The detailed report is for the benefit of those involved in the operation, planning and authorization of this type of flying activity and that is a pretty niche field.

Didn't roll out of the manouvre when he might have done.

Am I missing something here, because the escape manoeuvre is simply to roll upright at the top or very shortly after the top and fly away.

We learned the roll off the top aero very early in our RAF training.

Missing ... The recognition of the need to change the plan - awareness, altitude margins, pre planned alternatives.
The human element ... vs pilot error.

It might be worth noting that Sussex Police have an active investigation into the circumstances of this accident.

"The entry height of the manoeuvre was consistent with the 200ft minimum height on the pilot's DA for a Jet Provost; the apex height and speeds on the accident manoeuvre were consistent with those flown in the Jet Provost the previous weekend"

Point 22 Page 197.

Safety gates are fundemantal to low level aerobatics and were taught when I was instructing even if at medium level. Sadly, they seem to have been ignored in this case.

Unfortunately, the expected report. Also, unfortunately this accident has degraded all flying displays in the UK for the foreseeable future. Very sad for all aviation enthusiasts but even sadder for the victims families. May you get at least some consolation that the truth is now out. I say no more.

I rather suspect AH will have been taught about gates and all other things being equal I'm sure would have been well aware of them.

Having had a quick scan of the whole report can I ask ddoes anyone with any Hunter background (I don't) have any opinions about the comments in the report about the "left" side altimeter ..e.g; ease of reading, tendency to possibly lag at high rates and "stickiness"..page 49/50 of the report refers to that particular altimeter's behaviour on a previous display that may be of interest; also in the appendices: page 417 makes interesting reading.

If you feel you don't need to base your assumptions on the entire report, or just can't be bothered to read it, then you are missing a LOT of facts. The report explains the limitations of the evidence available and the contradictory evidence from various sources. Altitude and airspeed data and engine performance are just two of these, which are important factors.

The established facts, the tolerances of acquired data and the limitations of the evidence available are far from being a niche field. There is a lot of evidence in the body of the report that do not entirely match the summary - and I'm only half way through reading it so far.

Just to offer an example: "Disassembly of the Mk 30B and further testing identifed an open circuit across the rotor windings of the synchro-transmitter. It also confirmed that the power failure flag had come off its pivots, probably as a result of the accident impact.
Disassembly of the synchro-transmitter, and examination under a digital stacking microscope, identifed that one of the input wires to the rotor winding was broken, which could account for the open circuit. This damage was probably not accident related, but there was no way to determine how long this condition had existed."

And: "Cockpit video evidence indicated that the g-meter was not working during the accident flight". There's lots of information like that in the body of the report. But your expert examination of a summary would clearly dismiss that as relevant.

A reminder to all posters that the British press will undoubtly monitor social media (yes, also this Pprune forum!) for quotes and the like. :*


Be careful what you post! :=


Especially now this is "hot news"... :rolleyes:

The Mk30/Mk29 combination of altimeters is used in both the Tucano and Canberra, albeit with one in each cockpit. As the report states, the Mk30 is a very accurate servo altimeter, but without 115vac it will freeze. The Mk29 when used in Reset will effectively mimic the Mk30, but will still allow a different pressure setting to be used if needed.

If the Mk29 is left in Standby then it ignores the electrical input from the Mk30 and becomes a normal (none-servo) altimeter. It does have a vibrator to help eliminate stiction. In the Canberra the Mk29 was the main altimeter for the pilot (the nav had the Mk30) and was often used in standby mode. Although not quite as 'smooth' as the Mk29 it was perfectly useable for aeros. Spent many aeros sequences in the back of a Tucano watching the Mk29 in either mode and it was perfectly good in either!

Even if its wasn't covered in Hunter 'ground school', I'm just amazed that AH didn't wonder what the R/S knob on the LH Mk29 altimeter did in the Hunter. I simply can't comprehend any pilot (therefore naturally inquisitive) not wanting to know.

Thanks HP.

Having read the report, a couple of points that stand out:
The vapour plume from the fuselage, seen on video after the Derry turn, is not identified or commented on.
The considerable thrust reduction caused by the engine only achieving ~7500rpm in the pull-up compared with the 8100rpm for full thrust is not quantified.

Onceapilot

Having scanned the report again tucked away there do seem to appear to be a few "open items", mainly in the appendices, mainly in Human Factors: e.g. elsewhere:

Yet one assumes that the people writing the summary and those that have reviewed the report over the months of the consultation period are fully familiar with that detail and therefore the summary and its recommendations are entirely based upon the detail and accepted details - or you don't agree?

Wiggy. Later in the report it also states:

"The rpm at pull up (derived from the spectrum analysis of the action camera audio) was 7,530 audio, which reduced to less than 6,800 audio, possibly as low as 6,500 audio during the upward half of the manoeuvre and was increased transiently to 7,210 audio. It was 7,010 audio at the apex. This was contrary to the pilot’s declared nominal power setting of increasing to full power at or shortly after the pull-up. The throttle was not visible on the video and so it is not possible to confirm whether the rpms were pilot selected or due to an engine malfunction."

The number of variations in engine RPM (from the graph in the report) during the manoeuvre do not make sense. I know of no one that continually and deliberately moves the throttle(S) around that much during a loop ("bent" or otherwise), particularly pre-apex.

Pittsextra,

No, I don't. Not from what I'm reading in the body of the report. There are too many significant findings in the body of the report that are not reflected in the summary. Known instrument failures/malfunctions/miscallibrations and issues with the engine fuel control leading to very significant rpm reductions during the manoeuvre are all potential causal factors. In fact, I think they know the summary is incomplete as there are a number of issues where they have stated that they may report further on certain issues later. That smacks of an incomplete investigation.

So the pilot enters the manouvre at 185ft, his minimun height should have been 500ft, Entry speed 305 kts, should have been 350 kts, so at the point of entry things are no going well and negligent. Then full power is not applied, then the pilot fails to meet his target height of 4000ft and speed is 105 kts. In interview the pilot does not know the speed for the escape manouvre. Not really convinved that he had confused the speeds and safety gates between the JP3/5 and the Hunter, surely he knew what aircraft type he was flying. The report states he couldn't recall anything after the Wednesday before the accident, but while being treated at the accident site, he was lucid and reported feeling unwell prior to the flight. Yet this fact can not be established. Again if he felt unwell why did he continue with the display?

It will be interesting what the Police's next move will be. I would imagine he has tranfered his aircraft, cars and house into his wife's name by now,

Homsap

Regards AH's memories of the event and the hours/days around it, before calling "foul" you might want to Google the likes of Post-traumatic amnesia (PTA).

As for your final comment, harsh and uncalled for, to say the least.

Homsap,

You seem either to be quoting the summary without reading the body of the report (which are very different) or you are being very selective and picking out bits that fit your assumptions.

Inform yourself before posting judgements, please.

Addendum regarding altitudes as an example (from the body of the report):

The rotational speed of air traffic control radar antennas is such that the information they receive is not updated sufficiently frequently for accurate tracking of aircraft that are continuously changing direction and speed.
Errors associated with aligning the recorded radar track with specific points on the ground include random errors and systematic errors. These vary for the different radar heads for a given aircraft track and complicate the mixing of positional data from different radar sources. Pressure altitude data, referred to as ‘Mode C’, from different recorded radar tracks can be more readily combined as this information is transmitted from the same aircraft's transponder.
Some of the Mode C altitude data was automatically flagged by the system as ‘Not-validated’, including a signi cant proportion of altitudes recorded during the accident display. However, this ‘Not-validated’ radar data appears reasonable when compared with the validated radar data and other evidence, such as the motion captured by imagery and results of photogrammetry analysis. Radar data validation is discussed further in Section 1.16.2.

It is, a whole paragraph.

Indeed, it is covered in the report, Pozidrive, you are right. Too many others jumping to conclusion without reading the report.

For a year and a half now, people have been complaining about how long it's taken to publish. Now it's here, they seem unwilling to read it.

Pozi,CM

I will give you the benefit of the doubt if you read what I wrote and confirm you understand.:rolleyes: The report identifies vapour, aparently from the wing tank area. The trail I refer to is from the fuselage/jetpipe and is visible in video online.

Wiggy...

I accept that he may later have suffered from from memory loss at a latter date, not least as he was placed into an induced coma.

I do not think my comments are harsh, if a pilot of a commecial flight crashed a aircraft as a result not abiding to DA/DH, approach speeds, or the regulated speed say below 10,000 feet, and as a result eleven people died, wouldn't we be calling it both professionally negligent and criminal.

Likewise, had the pilot been given too much morphine at the crash scene and died as result, wouldn't his family be calling the paramedics negligent and be suing the ambulance service.

But in fairness to the pilot, and putting aside any action by the police or CAA against him, whether he is in the right or wrong, I don't think anyone would want to carry the burden of guilt and in addition I would imagine 'on the balance of probabilty' through the civil court he will loose everything.

Again in saying I'm harsh, I do accept that in part the CAA are at fault as display authorision process is way out of date, which was the case in both this accident, the Gnat crash and others. Likewise you would think the local planning authority in conjunction with airports and the CAA, could place exclusion zones when displays take place, rather wasting their time investigating or persecuting people for illicit garden decking,etc..

Courtney Mil....

I think we all see things in a different way, and the 'selective' way I put it was as the events in terms of an error chain within say a few minutes, he may have misread the altimeter or ASI, or thought he was in a JP we will never know, as for the non application of power which might have been human error, if not had the engine malfunctioned, in any event in planning the display, I would hope the pilot might have had 'an escape plan' in the event of an engine or instrument failure at any stage of his display.

Too many assumptions as usual.

And if you can't be bothered to read a point correctly and apply basic comprehension - quit posting.

I'll spell it out...

There are basic flight safety points to be deduced from the evidence presented in the summary. They are obvious to any professional aviator (as we both are/were) especially those trained to instruct/supervise/authorise (I was, I assume you were too).

Those basic lessons are both obvious and timeless - the detail does absolutely nothing to mitigate them in anyway whatsoever. It merely offers a much richer and deeper level of understanding of the actual events and contributing factors. Note also I refer ONLY to basic/general (or high level, if you prefer) lessons - not one word about blame, or how the contributing factors combined to create the outcome.

If you don't know what general lessons I refer to, I'm slightly shocked and can only wonder at your agenda, since I believe your knowledge of airmanship, flight safety and human factors to be at least as good as mine.

Maybe I'm wrong about that.

And now I'll depart and leave discussion those that want to debate the detail, comforted in the knowledge that regulations regarding air displays will be both strengthened and more rigorously enforced, thank goodness.

Well,I've read it all. My thoughts:
More interestingly and probable far more wide-reaching:

Summing-up my initial, most worrisome, thoughts in a sentence - The air display scene lacked effective oversight and suffered from ingrained and institutionalised denial.

AH may have pulled the trigger, but the system both manufactured and gave him the gun.

I know the one you mean, there is a short trail immediately after he comes over the top of the loop.

There is a vapour trail from the jet pipe area at a couple of points during the flight (e.g. at about 4 seconds in this compilation https://www.youtube.com/watch?v=Mr4POEBz81s)

From memory, does the Hunter not have a fuel vent pipe in that genreal area?

There is no evidence presented in the summary; the evidence is detailed in the body of the report. The summary is exactly what it claims to be. The flight safety recommendations are detailed elsewhere in the report. If you have found any in the summary then they are your own deductions based on incomplete knowledge of the facts.

Who actually has the time or enthusiasm to grind through 400 pages!?

I do and I am.

I will also be reading the report from cover to cover, but I fear it will be difficult to aviod confirmation bias while reading. At least I will try my best to approach the report with an open mind, even though we all "know" what happened. :ugh:

...can you expand this element? i.e. which instrument, which malfunction and how do you see it as a potential causal factor.

As an ex Hunter pilot I shall read the full report before making any significant comment.

At the moment I will merely limit myself to saying the machine will happily loop at sea level at 300 kts and ISA, and gain height at the display weight. 350 kts is not required, and indeed may not be desirable if keeping the display tight is a priority.