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

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

Old 11th Mar 2017, 21:46
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Hi airpolice:--

I can't find where you get the idea that the AAIB suggest that the GoPro could see the Altimeter in G-BXFI that day. This is what I did find.
That is in the report - in a table I think. If you can't find it I'll re-visit tomorrow. Some of the report seems a bit wooly and subjective. Crammed with "factoids" but lacking any real conclusion. That's how it seems to me, anyway.

I'd send the report back to the AAIB and ask them to reconsider.
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Old 11th Mar 2017, 22:26
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Originally Posted by Lemain
That is in the report - in a table I think. If you can't find it I'll re-visit tomorrow.
Airpolice has already quoted the part in the report that confirms the camera could not see the altimeter.

You may be thnking of the table at the top of Page 51, immediately following paragraph 1.11.7.4 that you yourself quoted a few posts back, showing the altitude and airspeed parameters recorded by the camera fitted to the Jet Provost that the pilot had displayed the previous weekend.

Some of the report seems a bit wooly and subjective. Crammed with "factoids" but lacking any real conclusion. That's how it seems to me, anyway.

I'd send the report back to the AAIB and ask them to reconsider.
If you don't agree with the AAIB's analysis and findings, that's your right. But citing stuff that simply isn't in the report doesn't really help your case.
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Old 12th Mar 2017, 08:47
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Hi Dave Reid --

Firstly the 'wooliness'. From Paragraph 2.2.1.2 --

The RAFCAM HF report identified four reasons why the accident manoeuvre
may have been continued:
• The pilot did not check the altimeter.
• The pilot checked the altimeter but did not or could not read
it correctly.
• The pilot read the altimeter correctly but did not accurately
recall the minimum height required at the apex of the looping
manoeuvre for this aircraft.
• The pilot read the height correctly but decided that an escape
manoeuvre was no longer possible.
If a false understanding of his height at the apex led him to believe it was
sufficient to complete the manoeuvre, he would have had no reason to
discontinue it or eject.
Every bullet-point says "pilot error". Surely a complete scientific well-written report would have added the bullet point "The altimeter(s) indicated the incorrect altitude"? I'm not saying that the altimeter(s) necessarily were showing the wrong level but the absence of that possibility - however remote - indicates a bias or prejudice. I called that 'wooly'.

As for the cameras not seeing the altimeters on the accident flight, you are correct. The AAIB "deduced" that the static was OK from vision of the ASI, not the altimeter. Sorry for any confusion I caused. I think I should have printed the whole report and gone through it on the dining room table. Mea culpa.

However, the AAIB report does not explain how they 'knew' the static to the altimeters were intact -- it is an assumption. They're possibly right. An engineer earlier in this thread who has service experience on type during the a/c's duration of service told us that it was normal for the static to be checked EVERY flight owing to the kind of flying these a/c do. The report does not confirm when the last static check was carried out and the report states that there was a maintenance issue with the altimeter(s). I believe there is only one static which feeds both the ASIs and the altimeters. Given the dynamic nature of the "static" I think this should have been more carefully explained.

If this was a court case and I was a juror, I think - based only on the evidence of the report - I would be that awkward s*d who would hold out. Therein lies both the strength and weakness of a jury system, I suppose?

Edit: Since the case against the pilot is 'too low too slow' the ASI and altimeters are the most important evidence.

Last edited by Lemain; 12th Mar 2017 at 08:50. Reason: See Edit note above.
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Old 12th Mar 2017, 09:23
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Originally Posted by Lemain
Every bullet-point says "pilot error". Surely a complete scientific well-written report would have added the bullet point "The altimeter(s) indicated the incorrect altitude"? I'm not saying that the altimeter(s) necessarily were showing the wrong level but the absence of that possibility - however remote - indicates a bias or prejudice.
There you go again, misquoting the report.

It specifically covers the scenario that the altimeter may have been displaying the incorrect altitude as a contributory factor.
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Old 12th Mar 2017, 09:32
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Hi Dave Reid. I presume you agree that I have correctly quoted 2.2.1.2? Those bullet points only cover the possibility of fault by the pilot. Why did 2.2.1.2 not include the possibility of incorrect indication or, perhaps, referred within 2.2.1.2 a reference to some other section?

Which section/page are you referring to regarding the incorrect indication?
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Old 12th Mar 2017, 10:09
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Originally Posted by Lemain
Which section/page are you referring to regarding the incorrect indication?
Page 417:

"Altimeter displayed the incorrect altitude. At present it is not known if the altimeter was serviceable and displaying the correct altitude during the loop. Technical analysis is on-going by AAIB which may provide further information on this point. The altimeter is the only display of height available in the cockpit and so should this information have indicated that the aircraft was above the gate height then it would have led the pilot to believe the aircraft was at a safe height to continue with the manoeuvre."

Also summarised on Page 128 (Para b).
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Old 12th Mar 2017, 10:32
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So why was that possibility not made clear in 2.2.1.2? The pilot stands 'accused' (well, accused by his peers and the industry but seemingly not yet by the law) of pilot error. Yet the possibility of instrument error is submerged. Why? This pilot had 14,000 hours. An engineer says the static should've been checked before every flight. Apparently it wasn't.

The maintenance error on the altimeter wasn't a simple transcription error -- it was gross error. I might accept a numeral 1 for a 7, an 8 for a 9, but two digits were wrong. This suggests the wrong instrument not a simple mis-read. If the engineer was so inattentive to detail what else did he/she do with lack of attention to detail? These were servo altimeters with a static fed though a wing section.

If the tube had been leaky or even broken altogether it would have affected the indication of airspeed and altitude in a very odd manner dependant on speed and angle of attack of the wing section. The pilot could have been disoriented and given the wrong information.

If the technical argument is that the ASI suggested the static was OK then the report should explain the rationale. I don't know these specific instruments but surely the AAIB should have consulted engineers who would have some idea?
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Old 12th Mar 2017, 10:41
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Altimeter, really.

An experienced pilot does not need an altimeter to distinguish between 187 and 500 feet agl. And if this loop had been correctly flown , correct entry speeds, height and power setting, full, and had not used max pitch rate on the way up ensuring gate height or more, he could have tightened up the looping radius to ensure correct radius and recovery height on the way down AND would have had a safety margin of 500 feet to eliminate the possibility of ground contact.

It's as simple as that. What we may never knowing why it was so badly flown, and if AAIB can't pinpoint the causes no amount of speculation on Prune wil help!

( Never flown the Hunter but a lot of experience on the JP including some low level aeros)
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Old 12th Mar 2017, 11:08
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Lemain, you've clearly misunderstood some of the quotes you've used and are now guilty of completely muddying the waters.

Drop the reference to 'how can he make a mistake - he's got 14,000hrs'. How many hours had Hanna, Proudfoot, Girdler, Bullock, Guy B-W.....got?

The static system does not need to be leak checked before every flight. You are misunderstanding an ex-Bosconmbe engineer who stated the system was checked prior to ETPS inverted spinning exercises. How can you possible believe that you should do a leak check prior to every flight??

The T7's LH altimeter is not a servo altimeter when used in Sby mode. The RH altimeter is the servo which can feed more accurate data to the LH alt when the latter has been 'reset'.

If the static piping in the wing was leaking as you suggest then you'd get huge changes in 'static' pressure as the wing was loaded and then unloaded. Any pitch change would cause a very noticeable movement of the altimeter and a smaller jump on the ASI.

The slight lag on the LH altimeter would mean it's pointer was still increasing as the Hunter reached the geometric apex. For LL aeros the altimeter is scanned during the 2nd quarter of a loop, not a photographic snapshot at the apex.

As already highlighted, there is a very noticeable difference in the 'picture' out of the window between 2700ft and 3700ft. You don't need a pointer on a dial to tell you which is which.
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Old 12th Mar 2017, 11:33
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Lemain

The report is compiled from many smaller reports prepared at various times by many different people as the investigation into all aspects of this incident were examined. The feed pipes to the ASI and altimeters were too disrupted to be able to come to any positive conclusion as to whether they were serviceable or not. However at least two separate investigations were undertaken into each separate instrument and the conclusion was that these instruments were essentially working and reading correctly, with the caveat that the left hand altimeter may have been sticking and under reading at times. This does not work in the pilot's favour.

Because these instruments were examined separately and presumably by two separate examining teams, at different times, it is only natural that the reports on the instruments condition will vary slightly.

One item that cropped up in the report is that the altimeter settings on both the left and right altimeters were not set to 1013 mbar which was the correct QNH and QFE setting for the day. That shows a lack of attention to detail on behalf of the pilot, although it could be argued that the instrument settings were altered in the crash or while they were being removed for examination. That is rather unlikely, but it remains a faint possibility.

Circumstantial evidence from earlier in the flight obtained from radar returns also suggests that the aircraft was maintaining the appropriate altitude and speed and that these instruments were therefore working correctly.

The instruments, although old, were designed to be read at a glance by military pilots operating under stressful conditions. Although there will be certain light angles that reflect off the instrument glass making them difficult to read, this situation is relatively rare and of very short duration when the aircraft is manoeuvering aerobatically.

I suggest that any wooliness in the report is simply to avoid pointing the finger of blame directly at the pilot, which it is not the AAIB's brief.

The down wind takeoff, display notes folded in a pocket, altimeters not set, display minimum altitudes busted, loop entry at too low a speed, full engine thrust not selected, a failure to recognise the apex of the loop was too low, and a failure to initiate an escape manoeuvre, all point towards one conclusion. Given that the aircraft was essentially airworthy and that no gross faults have been found to which the crash might be attributed, it is only possible to conclude that the pilot was at fault. The pilot held a class 1 medical at the time and incapacitation due to medical issues is thought unlikely. The holes in the cheese line up.
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Old 12th Mar 2017, 11:38
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Hi H Peacock --

If the static piping in the wing was leaking as you suggest then you'd get huge changes in 'static' pressure as the wing was loaded and then unloaded. Any pitch change would cause a very noticeable movement of the altimeter and a smaller jump on the ASI.
Yup. I think you're right. It would be more related to AOA than pitch per se but the elasticity of the wing section as load varies might have opened a leak. The report specifically states that the static couldn't be verified due crash damage. The report also states that the altimeter indication could not be verified.

From my own flying I cannot disagree that the height discrepancy might have been obvious without reading an altimeter. But an opinion on that is totally outside my competence.

Anyway, may I wish you an enjoyable weekend and thank you for engaging in discussion
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Old 12th Mar 2017, 11:59
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Hi G0ULI --

One item that cropped up in the report is that the altimeter settings on both the left and right altimeters were not set to 1013 mbar which was the correct QNH and QFE setting for the day. That shows a lack of attention to detail on behalf of the pilot, although it could be argued that the instrument settings were altered in the crash or while they were being removed for examination. That is rather unlikely, but it remains a faint possibility.
What is the difference between a "faint possibility" and a "plausible explanation"?

Can you remind me whether the QNH set was the regional or what? Maybe I missed it but it isn't clear. Actual QNH North Weald, Shoreham, or the regional QNH? Obviously I'm not suggesting that in those met conditions this was a causative factor but detail is detail. The pilot is being accused of lack of attention to detail by a report that seems to be either lacking in detail or prejudiced.
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Old 12th Mar 2017, 13:08
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There is one possibility that we all seem to be tippy-toeing around - AH may just have been gash that day.
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Old 12th Mar 2017, 14:20
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Originally Posted by G0ULI
Lemain



One item that cropped up in the report is that the altimeter settings on both the left and right altimeters were not set to 1013 mbar which was the correct QNH and QFE setting for the day. That shows a lack of attention to detail on behalf of the pilot, although it could be argued that the instrument settings were altered in the crash or while they were being removed for examination. That is rather unlikely, but it remains a faint possibility.

Circumstantial evidence from earlier in the flight obtained from radar returns also suggests that the aircraft was maintaining the appropriate altitude and speed and that these instruments were therefore working correctly.

The instruments, although old, were designed to be read at a glance by military pilots operating under stressful conditions. Although there will be certain light angles that reflect off the instrument glass making them difficult to read, this situation is relatively rare and of very short duration when the aircraft is manoeuvering aerobatically.

I suggest that any wooliness in the report is simply to avoid pointing the finger of blame directly at the pilot, which it is not the AAIB's brief.

.
Still wading my way through, but thinking of the altimeters here is my tuppenceworth.

AAIB Report p60 1.12.3.6 Altimeters

As found in the cockpit, the barometric pressure setting on the left altimeter was 1014 mb and on the right altimeter was between 1016 and 1017 mb.

This effectively a single seat (albeit trainer version) aircraft. The right altimeter is for the RH pilot – it is not a “secondary” altimeter for the LH pilot, and therefore would not be customary for the right altimeter pressure setting to be adjusted when flown solo. It might have been used as a cross-check pre-start?

Left altimeter - crucial for it to be set to the QFE for the airfield for a display – one of the important checks a display pilot will make on the display R/T frequency. I note you have stepped in to criticise the pilot for having the “wrong pressure set”. Maybe you could look up the METARs for EGKA on the day in question and the QFE the pilot was likely passed. Clue – it is unlikely to have been 1013.

SA 22/08/2015 12:20-> METAR EGKA 221220Z 12012KT CAVOK 24/17 Q1013=
SA 22/08/2015 11:50-> METAR EGKA 221150Z 11011KT CAVOK 23/17 Q1014=
(accident 1222Z)
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Old 12th Mar 2017, 14:44
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"This pilot had 14,000 hours."
If he had 14,000hrs-or even a third of that, on Hunters/Fast Jets this observation would have some relevance.
He didn't, so it doesn't.
Furthermore, even if we accept (and I'm not sure I do) that the altimeter may have not been working correctly, a pilot more experienced in low-level work would have looked at the 500ft indicated and the less-than-200ft terrain clearance and known something was wrong. IMHO of course.
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Old 12th Mar 2017, 14:45
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Wide-Body - thanks for reminding us of the METARs, and also for your suggestion that 1013 was unlikely.

Probably not worth mentioning, but since the elevation of Shoreham (EGKA) is 7 feet (2 metres), QFE and QNH will almost always be the same. So the 'Q' in the METAR could probably be taken to mean QFE as well as QNH. And the unlikely happened in this respect too, on a day when many other unlikely events coincided.

Last edited by airsound; 12th Mar 2017 at 14:49. Reason: adding unlikely things
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Old 12th Mar 2017, 15:48
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One millibar or hectopascal equals roughly 33 feet or 10 metres. In the overall scheme of things where errors of hundreds of feet were involved, the altimeter settings cannot really be considered a contributory factor in the incident.
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Old 12th Mar 2017, 16:16
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Agreed, not relevant, nor was that the point of my post. It was your statement:

That shows a lack of attention to detail on behalf of the pilot…

which I was highlighting as incorrect on your part, and the evidence appears to indicate the pilot had set the correct altimeter setting one would expect.

Maybe you could withdraw the incorrect accusation?
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Old 12th Mar 2017, 17:11
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In all the years I have flown from Shoreham I can only remember one occasion when the QFE and the QNH were not the same. Even then, the difference was a staggering 1 hpa/mb.

Since the QNH on the day was as near as dammit 1013 we can also take mis-setting of QNE (1013.25) out of the equation.

All in all, in this particular case, getting QNH, QFE or QNE confused is just one bloody great red herring!
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Old 12th Mar 2017, 17:37
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From page 43 of the report: "The aircraft took off from North Weald Airfield at 1204 hrs. The pilot occupied the left seat. Cockpit video indicates rotation was initiated at 112 KIAS. The pitch attitude was subsequently reduced and then increased again before the aircraft lifted off the runway."
Would this be normal for a Hunter takeoff?
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