AAIB investigation to Hawker Hunter T7 G-BXFI 22 August 2015
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Uplinker...
Some really good points and good questions. i touched on the issue of self briefing or mental preparation. I think or suspect the flaw with single crew display flying is probably the lack of briefing. If this does not already happen, perhaps it should be mandated that the display pilot runs through his 'gameplan' in the form of a briefing with another appropriate (mentor)display pilot (qualified on type). That way potential hazzards, airspace issues, weather could be raised. This could be done by telephone or Skpe.
In the case of AH he could have easily run through his briefing with say the othe Hunter display pilot CH (assuming he did not). as you say briefings usually flag up issues, speeds, airspace, weather, familiarisation with the airfield, defects, fuel and mass.
However having said that, in training pilots in the past particularly inrespect of single crew IFR operations, while I expect pilots to give me a depature brief and arrival brief, I have always suggested pilots flying as single crew read out the the arrival or departure briefing to themselves as it reinforces in their mind the gameplan. This works in the same way as reading back a clearence helps us remember, if we have not written it down. So readbacks is not only to confirm we understand ATC instructions but reinforces the instruction.
Some really good points and good questions. i touched on the issue of self briefing or mental preparation. I think or suspect the flaw with single crew display flying is probably the lack of briefing. If this does not already happen, perhaps it should be mandated that the display pilot runs through his 'gameplan' in the form of a briefing with another appropriate (mentor)display pilot (qualified on type). That way potential hazzards, airspace issues, weather could be raised. This could be done by telephone or Skpe.
In the case of AH he could have easily run through his briefing with say the othe Hunter display pilot CH (assuming he did not). as you say briefings usually flag up issues, speeds, airspace, weather, familiarisation with the airfield, defects, fuel and mass.
However having said that, in training pilots in the past particularly inrespect of single crew IFR operations, while I expect pilots to give me a depature brief and arrival brief, I have always suggested pilots flying as single crew read out the the arrival or departure briefing to themselves as it reinforces in their mind the gameplan. This works in the same way as reading back a clearence helps us remember, if we have not written it down. So readbacks is not only to confirm we understand ATC instructions but reinforces the instruction.
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The question about briefing is an interesting one, and my "confidence" in former RAF Pilots leads me to suggest that most solo display pilots in this type of aircraft would undertake a comprehensive "self brief" in the absence of a "supervisor". On this occasion I imagine AH was "on his own", apart from ground crew, because (I know) CH was in the Far East on holiday.
If one is looking to be critical of "human factors ", the downwind take off also raises a guestion mark. What was that all about and was that part of "the brief" (having completed performance calculations) - and noting that he needed to pull it off the runway at a lower speed than normal. Presumably because there wasn't a lot of runway left? Just how well planned and briefed was the entire trip? We will never know because AH can't remember anything.
If one is looking to be critical of "human factors ", the downwind take off also raises a guestion mark. What was that all about and was that part of "the brief" (having completed performance calculations) - and noting that he needed to pull it off the runway at a lower speed than normal. Presumably because there wasn't a lot of runway left? Just how well planned and briefed was the entire trip? We will never know because AH can't remember anything.
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If one is looking to be critical of "human factors ", the downwind take off also raises a guestion mark.
Remember, any owner wants to minimise engine cycles for cost so ten minutes saved here and there could be significant over time.
There was a suggestion on the original Shoreham thread that this could have been to minimise taxi time as the Hunter hangar was close to the threshold of that runway and it would have avoided a lengthy and time consuming backtrack. Provided the performance was valid (no idea whether it was or not but I have no reason to assume it wasn't - I suppose a Hunter person could work it out), there's no issue. I have done many downwind take-offs with no issues in that respect (albeit not in Hunters).
Remember, any owner wants to minimise engine cycles for cost so ten minutes saved here and there could be significant over time.
Remember, any owner wants to minimise engine cycles for cost so ten minutes saved here and there could be significant over time.
If it was to save taxi time then was it norm to land on Rwy 20 even accepting a slight tailwind?
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We will never know because AH can't remember anything.
There are some other parts of this report that I find strange:
At the apex of the manoeuvre the altimeter would have indicated that the
aircraft was approximately 800 ft below the minimum height that the pilot
stated was required.
aircraft was approximately 800 ft below the minimum height that the pilot
stated was required.
They captured the airspeed indicator and altimeter on both days but also suffered the same image contrast problems as the G-BXFI cockpit imagery when the
aircraft was inverted.
aircraft was inverted.
How about this:
The organiser of the flying display indicated that it had selected the FDD for his “significant experience in running air displays and his wide recognition within the air display
community”
community”
The accident flight
On the day of the accident the pilot was scheduled to carry out his sequence
of aerobatic manoeuvres in the Hawker Hunter aircraft at the Royal Air Force
Association (RAFA) Airshow at Shoreham Airport in Sussex. He had flown his
light aircraft to North Weald Airfield in Essex where the Hunter was based.
On the day of the accident the pilot was scheduled to carry out his sequence
of aerobatic manoeuvres in the Hawker Hunter aircraft at the Royal Air Force
Association (RAFA) Airshow at Shoreham Airport in Sussex. He had flown his
light aircraft to North Weald Airfield in Essex where the Hunter was based.
Terry, you asked:
If one is looking to be critical of "human factors ", the downwind take off also raises a question mark. What was that all about and was that part of "the brief"
The aircraft departed at 1204 hrs. The takeoff run was longer than usual due to
the high air temperature and tailwind, and the pilot raised the nose of the aircraft
to begin the lift-off at 112 KIAS instead of the 120 KIAS he would use normally.
Once airborne, the aircraft flew towards the south coast east of Shoreham.
the high air temperature and tailwind, and the pilot raised the nose of the aircraft
to begin the lift-off at 112 KIAS instead of the 120 KIAS he would use normally.
Once airborne, the aircraft flew towards the south coast east of Shoreham.
and noting that he needed to pull it off the runway at a lower speed than normal.
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I can't think of any comprehensive source that would document every single flight by a specific aircraft (apart from its own technical records, obviously)
Relevant to the discussed 'test fight' earlier. Would local ATC not have a 'movements log'?
Relevant to the discussed 'test fight' earlier. Would local ATC not have a 'movements log'?
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What the report actually states about the camera evidence:
Can you reference the section of the report that comes from?
Perhaps you are getting confused with this, which in no way suggests poor performance on the part of a GoPro when inverted. The reduced value of the video comes from ambient light.
The images included a part of the ASI, some of the fuel system controls and
indicators, some of the oxygen system controls and indicators, the JPT indicator,
and occasionally the engine rpm gauge when the pilot moved sufficiently for it
to come into view21. Determining their indications was complicated by image
resolution, contrast and partial obscuration.
The altimeters, thrust levers, and many other indicators and controls, were not in the camera’s field of view.
indicators, some of the oxygen system controls and indicators, the JPT indicator,
and occasionally the engine rpm gauge when the pilot moved sufficiently for it
to come into view21. Determining their indications was complicated by image
resolution, contrast and partial obscuration.
The altimeters, thrust levers, and many other indicators and controls, were not in the camera’s field of view.
Why "would have"? We were told that the GoPro could see the altimeter. The report might have said "should have" or just "indicated". We are not told what the conditional tense is for. The report does state that the GoPro had poor performance when inverted:
Perhaps you are getting confused with this, which in no way suggests poor performance on the part of a GoPro when inverted. The reduced value of the video comes from ambient light.
1.11.7.4 Recent Jet Provost display flying
The pilot displayed a Jet Provost on both days of the weekend prior to the
accident. Cockpit video recordings from both displays were provided. They
captured the airspeed indicator and altimeter on both days but also suffered
the same image contrast problems as the G-BXFI cockpit imagery when the
aircraft was inverted. Two loops were flown as part of the display on both
days. The indicated airspeeds and altitudes for each of the loops are given
in Table 6. The wider tolerance of indicated altitude in the 'loop apex' column
accounts for the reduced quality of the video due to poor image contrast when
inverted.
The pilot displayed a Jet Provost on both days of the weekend prior to the
accident. Cockpit video recordings from both displays were provided. They
captured the airspeed indicator and altimeter on both days but also suffered
the same image contrast problems as the G-BXFI cockpit imagery when the
aircraft was inverted. Two loops were flown as part of the display on both
days. The indicated airspeeds and altitudes for each of the loops are given
in Table 6. The wider tolerance of indicated altitude in the 'loop apex' column
accounts for the reduced quality of the video due to poor image contrast when
inverted.
... We don't seem to be told why the pilot used the downwind but 14kt tailwind is trivial. When the a/c wants to unstick it does. To me that suggests the pilot was comfortable in his seat, and relaxed...
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Hi Airpolice
You asked --
Yes. 2.2.1.2 Page 163 I'll let you find it yourself because it's a very wordy paragraph and it'll clutter this thread.
Hi H Peacock -- You said:
I'm not going to argue with you 
Given that the pilot decided to do that, and given that he's suffering from retrograde amnesia so cannot tell us, why would a 14,000 hour pilot have taken off downwind? For myself I can remember every time I took off d/w and why, even decades later. No doubt every pilot could?
You asked --
Can you reference the section of the report that comes from?
Hi H Peacock -- You said:
A 14kt tailwind is most certainly not trivial, certainly not in a Hunter on a hot day! Thankfully the tailwind component on the day was somewhat less, but still significant. As to the comment about 'the a/c wants to unstick when it does', that wouldn't have worked on the 20 military types I've flown.
Given that the pilot decided to do that, and given that he's suffering from retrograde amnesia so cannot tell us, why would a 14,000 hour pilot have taken off downwind? For myself I can remember every time I took off d/w and why, even decades later. No doubt every pilot could?
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Lemain:
A crucial part of this is the term The available evidence
indicates that the aircraft reached a height of approximately 2,700 ft I think this relates to radar derived height info and the known issues with the aircraft instrumentation.
Having read again, and pasted here, the section you refer to, I am still unable to find a suggestion by the AAIB to support your assertion that:
Can you tell me where they say it has poor performance when inverted?
I started this thread to discuss the report. People selectively misquoting it is not likely, in my opinion, to result in a better understanding of the risks to flight safety. All three of my GoPro cameras work just fine when inverted.
2.2.1.2 The apex of the manoeuvre
The pilot looked down towards the general area of the flight instruments on
two occasions as the aircraft arrived at the apex of the manoeuvre but it is not
known which, if any, of the instruments he observed. The available evidence indicates that the aircraft reached a height of approximately 2,700 ft, which was below the pilot’s stated target, at an airspeed of approximately 105 kt, which was slower than normal.
Test flights indicated that the aircraft required a minimum of 2,700 ft to complete the second half of the manoeuvre and that consequently no margin existed for it to do so safely in this case. The aircraft did not achieve the target parameters at the apex of the manoeuvre because it entered the manoeuvre below the target airspeed and climbed with
less than maximum thrust. The maximum height achieved would also have
been reduced by any roll initiated before the aircraft reached a vertical attitude in the climb.
At the apex of the manoeuvre the altimeter would have indicated that the
aircraft was approximately 800 ft below the minimum height that the pilot
stated was required. Tests of the left altimeter indicated that under-reading and lag in its operation may have caused it to indicate an even lower altitude (see Section 2.3.1.1). It was not possible to determine what the altimeter displayed at the apex of the manoeuvre. However, the investigation found that when the altimeter indicated approximately 2,700 ft, the pointer would partially obscure the height counter, which provided the only indication of thousands of feet (see Figure 28).
The pilot stated that if the aircraft achieved a height below 3,500 ft he would
perform an escape manoeuvre by reducing the rate of pitch, increasing the
airspeed, rolling the aircraft upright and climbing away. The pilot had not
practised the escape manoeuvre he described, but the execution of such a
manoeuvre would have been consistent with his background and experience.
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.
The pilot looked down towards the general area of the flight instruments on
two occasions as the aircraft arrived at the apex of the manoeuvre but it is not
known which, if any, of the instruments he observed. The available evidence indicates that the aircraft reached a height of approximately 2,700 ft, which was below the pilot’s stated target, at an airspeed of approximately 105 kt, which was slower than normal.
Test flights indicated that the aircraft required a minimum of 2,700 ft to complete the second half of the manoeuvre and that consequently no margin existed for it to do so safely in this case. The aircraft did not achieve the target parameters at the apex of the manoeuvre because it entered the manoeuvre below the target airspeed and climbed with
less than maximum thrust. The maximum height achieved would also have
been reduced by any roll initiated before the aircraft reached a vertical attitude in the climb.
At the apex of the manoeuvre the altimeter would have indicated that the
aircraft was approximately 800 ft below the minimum height that the pilot
stated was required. Tests of the left altimeter indicated that under-reading and lag in its operation may have caused it to indicate an even lower altitude (see Section 2.3.1.1). It was not possible to determine what the altimeter displayed at the apex of the manoeuvre. However, the investigation found that when the altimeter indicated approximately 2,700 ft, the pointer would partially obscure the height counter, which provided the only indication of thousands of feet (see Figure 28).
The pilot stated that if the aircraft achieved a height below 3,500 ft he would
perform an escape manoeuvre by reducing the rate of pitch, increasing the
airspeed, rolling the aircraft upright and climbing away. The pilot had not
practised the escape manoeuvre he described, but the execution of such a
manoeuvre would have been consistent with his background and experience.
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.
indicates that the aircraft reached a height of approximately 2,700 ft I think this relates to radar derived height info and the known issues with the aircraft instrumentation.
Having read again, and pasted here, the section you refer to, I am still unable to find a suggestion by the AAIB to support your assertion that:
The report does state that the GoPro had poor performance when inverted:
I started this thread to discuss the report. People selectively misquoting it is not likely, in my opinion, to result in a better understanding of the risks to flight safety. All three of my GoPro cameras work just fine when inverted.
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I had mistakenly written that the AAIB report makes no mention of GoPro by name, it has however referred to GoPro 7 times and Action Camera at 29 other times.
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Hi Airpolice --
You asked:--
And from Appendix M Page 408 Paragraph 7 ---
Seems like a very sloppy and inconclusive report in places. Doesn't do justice for the victims, relatives, survivors or the whole display aviation community.
You asked:--
Having read again, and pasted here, the section you refer to, I am still unable to find a suggestion by the AAIB to support your assertion that:
Quote:
The report does state that the GoPro had poor performance when inverted:
Can you tell me where they say it has poor performance when inverted?
Quote:
The report does state that the GoPro had poor performance when inverted:
Can you tell me where they say it has poor performance when inverted?
1.11.7.4 Recent Jet Provost display flying
The pilot displayed a Jet Provost on both days of the weekend prior to the
accident. Cockpit video recordings from both displays were provided. They
captured the airspeed indicator and altimeter on both days but also suffered
the same image contrast problems as the G-BXFI cockpit imagery when the
aircraft was inverted. Two loops were flown as part of the display on both
days. The indicated airspeeds and altitudes for each of the loops are given
in Table 6. The wider tolerance of indicated altitude in the 'loop apex' column
accounts for the reduced quality of the video due to poor image contrast when
inverted.
The pilot displayed a Jet Provost on both days of the weekend prior to the
accident. Cockpit video recordings from both displays were provided. They
captured the airspeed indicator and altimeter on both days but also suffered
the same image contrast problems as the G-BXFI cockpit imagery when the
aircraft was inverted. Two loops were flown as part of the display on both
days. The indicated airspeeds and altitudes for each of the loops are given
in Table 6. The wider tolerance of indicated altitude in the 'loop apex' column
accounts for the reduced quality of the video due to poor image contrast when
inverted.
7. Review of video evidence. The in-cockpit video for the entry to the loop and the bent
loop itself was reviewed. The overall phases of the manoeuvre were identified and a set of
characteristics were defined for each second of video. These characteristics included pilot
head movements, instrument panel contrast, position of sun, and control movements made.
loop itself was reviewed. The overall phases of the manoeuvre were identified and a set of
characteristics were defined for each second of video. These characteristics included pilot
head movements, instrument panel contrast, position of sun, and control movements made.
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Lemain, it also doesn't criticise GoPro as having poor performance when inverted. The report points out that the video is of "reduced quality" due to contrast. The term "Poor Performance" seems to be of your making, not a phrase that the AAIB attribute to Go Pro.
The issue is that when (the aircraft) is inverted, the daylight coming in overwhelms the camera compared to the view when upright. The problem comes from the camera being fitted to an aircraft which turns upside down, not the camera being upside down.
Your original point about the camera being able to see the altimeter comes from the JP display, not the Hunter, I think, or did I miss that bit?
The issue is that when (the aircraft) is inverted, the daylight coming in overwhelms the camera compared to the view when upright. The problem comes from the camera being fitted to an aircraft which turns upside down, not the camera being upside down.
Your original point about the camera being able to see the altimeter comes from the JP display, not the Hunter, I think, or did I miss that bit?
Quite so.
The report makes it clear that being inverted didn't directly affect the operation of the camera.
Instead, it's a reference to the fact that both the pilot's and the camera's view of the instruments was affected when the panel was partly in sunlight and partly in shadow (e.g. when the aircraft was inverted) and particularly when the aircraft's relationship to the sun was rapidly changing (i.e. during aerobatic manoeuvres), hence the reference to "image contrast" in Lemain's quote.
Edit: Beat me to it!
The report makes it clear that being inverted didn't directly affect the operation of the camera.
Instead, it's a reference to the fact that both the pilot's and the camera's view of the instruments was affected when the panel was partly in sunlight and partly in shadow (e.g. when the aircraft was inverted) and particularly when the aircraft's relationship to the sun was rapidly changing (i.e. during aerobatic manoeuvres), hence the reference to "image contrast" in Lemain's quote.
Edit: Beat me to it!
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Hi airpolice: I think you must have missed that bit. Don't forget the conditional tense "would have" rather than "did" or "indicated". Obviously it's implausible that the GoPro didn't function when inverted - the report says that the recording was imperfect.
To be honest, as a bit of a language pedant myself, I think the report is unclear.
Edit:- Guys I'm not playing devil's advocate. I'm trying to put myself into the position of a lay juror at a trial. I think I know the cause having read the report and listened to all the comments here from experienced jet and display pilots. But there is a huge difference between "thinking you know" and "being certain beyond reasonable doubt".
But only the lawyers will be the winners.
To be honest, as a bit of a language pedant myself, I think the report is unclear.
Edit:- Guys I'm not playing devil's advocate. I'm trying to put myself into the position of a lay juror at a trial. I think I know the cause having read the report and listened to all the comments here from experienced jet and display pilots. But there is a huge difference between "thinking you know" and "being certain beyond reasonable doubt".
But only the lawyers will be the winners.
Last edited by Lemain; 11th Mar 2017 at 20:25. Reason: See my comment after 'edit'.
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Lemain, help me out here then, in relation to the Hunter crash flight, where did you get:
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.
We were told that the GoPro could see the altimeter. The report might have said "should have" or just "indicated". We are not told what the conditional tense is for. The report does state that the GoPro had poor performance when inverted:
The images included a part of the ASI, some of the fuel system controls and
indicators, some of the oxygen system controls and indicators, the JPT indicator,
and occasionally the engine rpm gauge when the pilot moved sufficiently for it
to come into view21. Determining their indications was complicated by image
resolution, contrast and partial obscuration.
The altimeters, thrust levers, and many other indicators and controls, were not in the camera’s field of view.
indicators, some of the oxygen system controls and indicators, the JPT indicator,
and occasionally the engine rpm gauge when the pilot moved sufficiently for it
to come into view21. Determining their indications was complicated by image
resolution, contrast and partial obscuration.
The altimeters, thrust levers, and many other indicators and controls, were not in the camera’s field of view.
Just a note about the take-off at NW;rwy 02 is downsloping about 1.5% for approx half it`s length,and the first third of it`s length is asphalt,then concrete.There are numerous `patch` repairs to the asphalt and a couple of `ripples`across it,which can cause the nosewheel to bounce on take-off or landing.The crosswind at the time was 160/10,but it can be variable along the runway length. The aircraft took approx 28 secs to be airborne,using the video on utube .Other videos of similar Hunters taking-off,also appear to be airborne in a similar timeframe.Aircraft acceleration initially also appears to be about 13-14 ft/sec/,for a thrust/wt. ratio of about .405..
Another reason to use 02 is that the overrun,and initial departure is over open ground,whereas,20 is `uphill` and over a main road ,golf course and trees.Landings are usually done on rwy20,,accepting light tailwinds by the Gnats and Hunters.
I was at NW preparing to fly a JP,and would have used 02 for departure ,but as word about the accident caame ,cancelled as the `fuel` was quarantined` in case it had been contaminated.
Another reason to use 02 is that the overrun,and initial departure is over open ground,whereas,20 is `uphill` and over a main road ,golf course and trees.Landings are usually done on rwy20,,accepting light tailwinds by the Gnats and Hunters.
I was at NW preparing to fly a JP,and would have used 02 for departure ,but as word about the accident caame ,cancelled as the `fuel` was quarantined` in case it had been contaminated.
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Re Aircraft times
I am not sure why there is any conversations about knowing the aircraft total times and cycles. All jet aircraft have maintenance and time limited components controlled by hours and cycles so it would be very strange if these are not readily available. It should be available at any time particularly when someone is signing the aircraft off as airworthy.
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With regard to camera recordings at high contrast levels such as sunshine and shade, it is worth remembering that even the very best cameras only cover a fraction of the dynamic range of the human eye. Even though a camera may not clearly display instrument readings, they might still be perfectly visible to a pilot.
AAiB reports are not intended to assign blame, merely to identify the cause(s) of an accident with the aim of preventing the same thing happening again. Given the detail contained in the report and the extent of the investigation, it is obvious that some of the content has been deliberately worded so as to present a neutral view. Taken as a whole, the report is quite damning in its conclusions, although for the reasons given, a great deal of care has been taken to ensure that no direct blame is assigned to any person(s).
AAiB reports are not intended to assign blame, merely to identify the cause(s) of an accident with the aim of preventing the same thing happening again. Given the detail contained in the report and the extent of the investigation, it is obvious that some of the content has been deliberately worded so as to present a neutral view. Taken as a whole, the report is quite damning in its conclusions, although for the reasons given, a great deal of care has been taken to ensure that no direct blame is assigned to any person(s).