Grob/Cirrus collision June 2009 - report out

[cats_five]

http://www.aaib.gov.uk/cms_resources.cfm?file=/5-2010%20G-BYXR%20and%20G-CKHT.pdf

[S-Works]

RAF accident reports always seem to be very well written and detailed.

[cats_five]

This is an AAIB report, not one written by the RAF.

[S-Works]

I don't think so. I think it is an RAF report in conjunction with the AIB. Been involved in a couple if them in my time and the structure is familiar and different to a normal AIB report.

Either way interesting reading.

[BossEyed]

The corresponding Service Inquiry report is here (http://www.mod.uk/DefenceInternet/AboutDefence/CorporatePublications/BoardsOfInquiry/ServiceInquiryInvestigatingTheAccidentToTutorGbyxr.htm).

[mary meagher]

They each have made a detailed and comprehensive report. I have been sent a copy from the RAF, and have read the one from the AAIB as well.

The instructor in the Tutor, which was performing aerobatics in a very very crowded air corridor, ran into the rear of the glider, which was in straight flight at the time. It transpires that the instructor suffered from a condition which made it difficult to turn his head sufficiently for a good scan.

It is also possible that the condition rendered him after the collision unable to recover from the spin, although the Tutor was still fit to control.

The whole program in my mind is in need of serious overhaul. I would not dream of giving aerobatics to kids, or indeed to anyone until they were well advanced in training. The RAF is very defensive indeed on the whole matter, as you may see from reading their reaction to the other midair concerning their Tutors, also in 2009. This may be found in the military forum on PPRuNe.

[A and C]

I have to totaly disagree with you on the subject of aerobatics with ATC cadets, these young people are motivated and take responsibility well, They would not respond well to the nanny state wrapping them in cotton wool.

The report bring's into question two things, the pilots ability due to a medical condition to maintain the very high standard of look out required for aerobatics and the quality of the escape training that was avalable to the cadet.

It would seem that the pilot was incappacitated and even with the training that has come into question the cadet initiated the escape drill, unfortunatly time was not on the cadets side.

This accident shows me that young people given training and encouragement respond well and as shown in the report will take resopnsibility and act corectly even in extream situations.

As a cadet in the ATC I was shown a loop on my first flight in the chipmunk, this and the rest of the training in the ATC set me on course for a lifetime of aviation..............I don't intend to see the "elf & safety" nanny state take away those oportunitys from the youth of today.

[Cows getting bigger]

I detect a mud-slinging session brewing. To me, Class G is quite simple. We all value the freedom it gives us and cherish the lack of regulatory interference. However, there are disadvantages. Yes, you could ask whether the VR(T) pilot was fit enough to fly cadets; the medics appear to have said so. You could also ask about the merits of aeros in uncontrolled airspace.
Equally, you could ask why we are faced with a fraternity who make little effort to increase their visibility (How come the ATC manage to 'paint' dayglow stripes on their gliders?) and have a reputation for not reading the NOTAMs (eg Red Arrows at Siverstone).

But, the bottom line is that Class G is a jungle and we all have a part to play. Trying to highlight elements of an accident report in an apparent attempt to apportion blame is off-side and completely counter productive. Yes, the cadets may need to do some soul-searching but I don't think any of us have the right to take any moral high ground.

[NigelOnDraft]

I wrote the following in response to Mary in the Mil Aircrew forum, to a similar post by her there:Mary...

Prior reading your post I read the whole 107 pages off the AAIB report.

I then read your post. A couple of major disagreements:

Quote:
by the whole mess

It was not a "whole mess" IMHO. It was a tragic accident, unforeseeable, but lessons have been learned.


Quote:
and by the practice of giving young teenagers aerobatics on a first or a second flight

Quote:
if aerobatics had not been normal practice, there might have been a better outcome

Quote:
and that in the future, aerobatics are not offered until the student is well advanced

You clearly have some concern, even obsession with "aerobatics"? The AAIB report list 13 recommendations, the word "aerobatics" features not once in these.

My reading of the report is that the aerobatic maneouvre, whilst it did immediately precede the collision, could equally have been a turn. Furthermore, there was no "student" involved - but a "passenger". That passenger could have been on their 1st, 2nd, 10th or 100th flight and what difference would it have made?

In short, and IMHO, a tragic accident with nobody culpable, nobody doing anything other than trying their best to give young people a supervised experience in life, one that did carry risks, but the best of intentions to reduce those. Lessons have been learnt, and I am not sure that without the accident, they could/would have been unearthed?

In short, AEFs have for many years given many cadets truly memorable experiences, with few incidents. A bad run last year, but my understanding is that the "uptake" in such flying by parents has been more realistic than your post suggests, and continues largely unaffected.

NoDI see little different in her post her to alter my reply.

My only concern might be I have been sent a copy from the RAF and wonder if Mary is directly affected? In which case, my words would probably sound harsh for which I apologise.

NoD

[L'aviateur]

General Aviation, including the Air Experience Flights has an inherant risk associated with it. Of course, a good aviator does all he can to reduce those risks to an acceptable level and more.
We could of course become transponder mandatory, with flight plans required before all VFR flights and remain in contact with a radar service at all times. Personally, I wouldn't want this. I value the freedom outside controlled airspace to 'play' around responsibly whilst keeping a proper visual lookout, I like the idea of being able to freely follow a river, climb up to 3020ft and back down to a 1092ft or track a coastline or perform aerobatics.
The unfortunate result is these kind of tragic accidents, but lets face it we'll never eliminate the risks, and everyone going up into these skies knows (or should be aware of) the risks they face.
This could be said for many other activities, including riding a motorcycle, climbing, extreme sports etc.

[cats_five]

<snip>
Equally, you could ask why we are faced with a fraternity who make little effort to increase their visibility (How come the ATC manage to 'paint' dayglow stripes on their gliders?)
<snip>


Have you read the Cranfield Glider Conspicuity study?

http://www.dg-flugzeugbau.de/Data/glider-conspicuity-study.pdf

[A and C]

Thank you..............I was about to add that one!

[Rod1]

The Glider had FLARM and the Tutor mode S. If the Tutor had had a FLARM (£580) it would have given lots of warning of the Glider long before the collision. If the Glider had had PCAS (£400) it would have detected the Tutor long before the collision. The report gives an indication of the level of traffic in the area, which is quite astounding. It also points out that assisted see and avoid (using a system like FLARM or PCAS) is 8 times more effective than unassisted see and avoid.

The BGA has been proactive in encouraging its members to fit collision avoidance, perhaps others should do the same.

Rod1

[snapper1]

The RAF report concludes that conspicuity was unlikely to have been an issue as the Cirrus would have presented a plan view to the Grob crew who were in an almost vertical climb immediately prior to the collision. There were no NOTAMS relevent to the air activity in the area on the day. The medical issue is stated as a potential contributory factor in the RAF report.

Whilst I can understand aerobatics being an important part of air experience flights, would it not be prudent to discontinue them on a very busy day in a very contricted area?

[The Old Fat One]

It's not "defensive" to insist on the facts when discussing a fatal accident. So to clarify here, as I have done on the military thread...

Air Experience Flying (AEF) is not flying training; there are no students, only passengers (generally Air Cadets). AEF is part of the broader aviation related activities of the Air Cadet and Combined Cadet Force organisation, which includes gliding scholarships and flying trainining scholarships. The flying training scholarships are provided under CAA regs at a civilian FTO following the PPL syllabus.

I do not believe that anything whatsoever can be gained by arguing whose approach is the safer, but comments like " the whole programme needs an overhaul" need to be placed in the correct context, by comparing like with like. There have been a great many "ill informed passengers" killed in light aircraft accidents, including many who have been the unknowing victims of horribly poor airmanship and flight safety awareness. Many of these accidents have been played out in the full spotlight of the media.

As far as flying training in the UK is concerned, accidents are few and far between - incluing all the different scholarship programmes.

So I see no compelling case to overhaul anything in approved flying training and if the regs regarding the carriage of passengers need looking at, there seems to be a far greater need in ordinary GA, rather than in a specialised outfit like AEF.

Be careful what you wish for.

[UAV689]

Without doubt it is an awful accident to have happen, especially so close to the St Athan accident as well.

But we must as a society restrain ourselves from going down the nanny state route, from stopping youngsters having this experience. How many 1000s of cadets have taken part in an AEF flight, and how many accidents? I imagine the ratio is massively low.

How many children from poor backgrounds (myself included!) would never have experienced a flight or aerobatics if it was not for the AEF, it cannot stop, to do so would be criminal, once you lose something like an AEF it will NEVER return.

Mary I have to disagree with you on this one. How is it different from a parent sending their Kid off to a civi school to do aeros in an ex-RAF bulldog at some uncontrolled airfield? Is that to be banned as well? In my eyes the AEF are safer, these chaps that take them up are hugely experienced ex service pilots, I have flown with many of them and they have forgotten more about flying than I will ever know. Much respect to all the AEF fraternity.

UAV

[MichaelJP59]

I like Rod was struck by the level of traffic in the area, I haven't seen an analysis like that before. Also amazed by 70-80 gliders launched per hour by Lasham, an eye-opener for me, and especially without a NOTAM being necessary.

[sammypilot]

Any comment from an AME as to whether a PPL would have got a Class 2 Medical if he was suffering from the same medical condition as the Tutor Instructor.

[Torque Tonight]

I too sympathize if Mary was in some way directly affected but a kneejerk reaction is not what is required here. The AEF has an excellent safety record and over the years has done a great deal of good for young people and aviation in general (not just military). It is not possible to achieve a zero accident rate in aviation and life would be very boring if we were totally risk averse.

[Fitter2]

I like Rod was struck by the level of traffic in the area, I haven't seen an analysis like that before. Also amazed by 70-80 gliders launched per hour by Lasham, an eye-opener for me, and especially without a NOTAM being necessary.

On a good weather weekend day this is normal activity. How many movements are there at a busy GA airfield, un-NOTAMed? I understand you can only normally NOTAM activity from a licenced airfield, scheduled gliding competitions being a permitted exception. And what practical use would a NOTAM saying there may be up to 1,000 gliders flying in UK Class G airspace?

What is also normal is that the choke point between the Brize zone and the TMA has a high density of cross-contry gliding activity, given the number of gliding clubs in the area, and the limitations of where else to route a task. If you are in that area on a good summer's day, and don't see several gliders, it's probably because you aren't looking for them.

[MichaelJP59]

On a good weather weekend day this is normal activity. How many movements are there at a busy GA airfield, un-NOTAMed? I understand you can only normally NOTAM activity from a licenced airfield, scheduled gliding competitions being a permitted exception. And what practical use would a NOTAM saying there may be up to 1,000 gliders flying in UK Class G airspace?


Normal activity but a surprise nonetheless. I doubt if you'd get 70-80 aircraft taking off in an hour at a busy GA field, unless a Duxford airshow's just finished:)

As for a NOTAM, one saying we will launch 120 gliders between 1000 and 1130 UTC would get the attention. As the report under discussion says, maybe there ought to be a better i.e. quicker and easier way of notifying GA about things like this than the current system.

[UAV689]

another problem is the lack of understanding between power pilots and glider pilots and vice versa.

During the summer you will always get an airfield somewhere in the country at a given week hosting a competition that will launch that many gliders in a few hours, not really of a surprise to glider pilots but a massive one to some power folk.

Much in the same way some a/c fly striaght over a gliding site @ 1500ft in the way of a 5mm steel cable traveling invisbly through the air at 50mph...

If a greater understanding could be gained of each others needs then safety would be improved no end.

[ProfChrisReed]

Having read both reports there are two elements which I don't think anyone has mentioned yet but are worthy of note:

1. The effect of controlled airspace in the area was to funnel most traffic into a very small area - the AAIB report even says that because traffic tends to stay in the middle of the Brize "corridor" (presumably to reduce the risk of airspace infringement) the concentration was even greater than the chart would suggest. This problem of choke points seems not to be considered in controlled airspace design - for example, the recent grant of controlled airspace to Doncaster produced new choke points.

2. Both reports conclude that the Tutor pilot;s medical condition would have made him unable to undertake a proper lookout, particularly overhead, as is necessary for aerobatics such as loops. The MoD report seems to suggest that the pilot would probably not have realised that his lookout was inadequate for the flying he was doing, which makes sense as I cannot think that a pilot with his level of experience and background would have intentionally subjected the cadet or the glider pilot to this risk. This raises the question how we, as pilots, should assess changes to our capabilities. For example, I am aware that age has reduced the suppleness of my own neck (though I don't suffer from AS I'm happy to say). As a glider pilot I am conscious of my lookout capabilities and try to monitor whether I'm capable, and have annual instructor checks which I hope would note any failings - but what else am I missing and how could I know?

[Flying Lawyer]

mary meagher The whole program in my mind is in need of serious overhaul.
As you say, it's in your mind.
The reality is that the AEF programme has an excellent safety record. Keeping programmes under review to see if any changes are necessary is a different matter, and wise.

I would not dream of giving aerobatics to kids, or indeed to anyone until they were well advanced in training.
I don't understand why you hold that view, but it's your choice. I'm very pleased I didn't have to wait until I was well advanced in my training before aerobatics were demonstrated to me.

The RAF is very defensive indeed on the whole matter, as you may see from reading their reaction to the other midair concerning their Tutors, also in 2009. This may be found in the military forum on PPRuNe.
That's very unfair.
I have considerable experience of closely examining air accident reports in my former job and regard the RAF Inquiry into the midair collision of the two Tutors as thorough and entirely objective. The AAIB report into the incident is currently in draft form and will be published late this year or early next. We'll see in due course whether the AAIB findings differ greatly, or at all, from those of the RAF Inquiry.
You appear to have a chip on your shoulder about the RAF.
I read several RAF Reports in my former job and, with one exception, was impressed. The exception was an occasion when an RAF Board of Inquiry found that an RAF pilot caused an accident which was clearly the fault of a PPL. The AAIB Report was more balanced and IMHO more accurate.


.

[bad bear]

Lasham does run at around 200 movements per hour on good club weekends and competitions. A previous survey of the Didcot area done 7 years ago as part of a UKAB reprort showed slightly higher figures for traffic density over a longer period.
The interesting question is WHY do so many aeroplane and gliders follow this route?
Answer? because they are avoiding Controled Airspace that is almost empty!
So, how many movements were there in Brize that day? If Brize or other controlers of empty air were to have a better system of allowing guaranteed transits the density would drop dramatically.
There is really only one ground track for VFR pilots to follow from the south west of London north bound. We need less controlled airspace.

The report itself makes sad reading and I cannot imagine how the cadets family must feel.
bb

[Katamarino]

You appear to have a chip on your shoulder about the RAF.

Mary's previous posts suggest that she has a chip on her shoulder about powered aircraft in general; given that, I tend to disregard her views on the subject :ok:

[421C]

The only thing worse than Regulators regulating GA would be pilots doing the regulation.....

The pilot forum tendency to want to ban things, impose more regulation etc is quite extraordinary, but it does give you an insight into how we end up with the regulatory environment we have, when people react in a "from first principles, my personal reaction to this issue is...." way.

OK, there is a worse thing. If pilots, rather than regulators, ran enforcement actions. The pilot forum 'lynch mob' tendency, when confronted with the scantiest hint that another pilot did something wrong is scary. (Not prevalent on this forum as much as another I read at times).

brgds
421C

[MichaelJP59]

I've had transits through Brize, but I guess getting a transit for a transponder-less glider might be harder.

Also a lot of people would rather stay in class G and not bother with all the extra radio calls. Another factor and I know it's probably not like this but I always feel as though you're asking the busy controller for a favour to get the transit.

[Rod1]

The last twice I have been down that way I have transited the Brize zone. Now I understand just how busy it is through the gap, I will be avoiding it!

Rod1

[cats_five]

Mary's previous posts suggest that she has a chip on her shoulder about powered aircraft in general; given that, I tend to disregard her views on the subject :ok:

Surprised as Mary flies power as well as flying gliders, so has seen it from both sides of the divide, which is more than most of us have. As far as I know she has a considerable number of hours in both gliders and power, and when I visited her club a couple of years ago she often flew their tug.

However, two gliding friends are horrified (sorry but that's about the measure of it) that the pilot was allowed to continue flying P1 with his spinal problems and the difficulty he had in doing a satisfactory lookout. One of those friends has a PPL as well, and I believe they would have been equally horrified at him flying P1 with or without an engine.

[greenedgejet]

Having read both reports there are significant differences as well as points of agreement:

SEE AND AVOID:

Both reports state the glider pilot heard the Tutor before making a considerable visual search.

Speed of sound v speed of light - the Tutor is hard to see unless there is contrast (eg: dark sky behind).

He then saw the aircraft in planform about 200 - 300 feet away before it suddenly pitched up towards him. Had he seen it 6000 feet away things would have been very different.

The SI report plays down the Tutor conspicuity issue by mis-quoting from the Cranfield University document: The SI says the study concluded that black undersides "marginally" improve visibility whereas the actual document states "significantly". It also says "Dayglo (R) stripes effectively reduced the range at which the aircraft was detected".

However, the Cranfield report states "the two studies, in 2000 and 2002, which examined conspicuity of MG during constant bearing convergence, have failed to demonstrate a significant increase in detection distance with the use of the DayGlo© patches on the MG. However, there appeared to be no measurable negative effect upon conspicuity either."

The Welsh SI report states that Grob were willing to trial an all black Tutor.

LOOKOUT:

The SI starts off suggesting the Spinal issue was a factor and concludes it was the main issue along with authorisation issues and medical clearances.

Although the QinetiQ trials were published for the Welsh accident SI, the AAIB considers the Tutor canopy design:

VIEW OUT:

The radar traces show the Tutor entering a decent before pitching up rapidly. Most EFT aerobatic lookout is taught pre-manoeuvre (above and behind) and wingovers are often used to position and clear airspace before a sequence.

Whilst the AEF pilot's spinal problems have been well documented, the canopy arch design is a significant factor in the AAIB report.

Considering the dive to acquire speed (130KIAS for a loop) may have been post initial lookout, the arch at 2 o'clock high becomes a real blind spot. If the crew were properly strapped in then looking around it would have been difficult even without spinal problems.

Then during a loop, once feet are above the horizon, where do AEF pilots look? To the wingtip(s), 2nd half to line feature ahead? Does 4G not prevent some head movement around cockpit obstructions?


CANOPY "JETTISION":

The difficulties associated with the Tutor's "jettison" mechanisms above 100 KIAS:

The AAIB includes Police interviews with other 14 year old cadets about how to exit a Tutor aircraft. None of them knew the correct method and the safety video shown to them has since been changed.

The evidence shows the passenger on this tragic flight tried to exit the aircraft after collision. It is unlikely he pulled the red locking device before operating the main handle although it was found in the LH footwell post crash.

The manufacturers tests did not jettison a canopy in full but tested the latch system up to 100 KIAS. Anyone who has flown a G115E will know how difficult it is to move the canopy back a few inches to ventilate the cockpit unless the aircraft is slowed to 80 KIAS or below.

AIRSPACE / CONGESTION:

Clearly a major factor with choke points of CA, numerous gliders and GA below 5000 feet.

Vertical separation: AEF sorties are around 20-25 mins long. In that time a Tutor can just about climb to 10000 feet but then the sortie length leaves no time for anything else. Airspace permitting, a more powerful machine could do aeros at 8000' without height loss - away from GA at 2000' and the congested 4000' layer that day.

AERODYNAMICS:

In addition the AAIB investigated Spin and Longitudinal Static stability of the machine in their consideration of aircraft controllability post glider collision.

The conclusion was the Tutor can recover itself from a spin but not a vertical dive.


Overall, the Tutor is a fine AEF/GA machine in clear airspace but there are limitations that even TCAS can't address.

[Flying Lawyer]

421C The pilot forum tendency to want to ban things, impose more regulation etc is quite extraordinary, but it does give you an insight into how we end up with the regulatory environment we have .....

The pilot forum 'lynch mob' tendency, when confronted with the scantiest hint that another pilot did something wrong is scary.

I agree. :ok:
It may be because so many of the posters in this forum are Brits. Most Brits actually like rules and regs; perhaps it's a symptom of our 'nanny knows best' culture.

I've often noticed that even when PPLs ask if it's legal to do something they are inundated with a variety of reasons why it would be illegal. Many of the reasons given display great and often tortuous ingenuity. In contrast, very few contributors put the same degree of effort or ingenuity into coming up with a way in which the objective could, perhaps with a minor variation, be achieved entirely legally.


FL

[A and C]

I envey your ability to get right to the heart of the matter, the British have a culture that assumes that unless there is a rule that permits something it must be wrong and you can't do it.

This has resulted in the "elf & safety" culture that is putting huge burdens on us all, fortunatly there is light at the end of the tunnel with the soon to be relesed report by Lord Young, I understand that this is should result in the rolling back of the "nanny state".

We also have an aviation regulator that thinks it is the final word on aviation regulation within the UK and keeps trying to gold plate EASA regulations, the sooner they cop on to the fact that they are now only the UK office of EASA the better. I suspect that some work may be coming your way as the CAA are being overly restrictive and inventing reasons not to issue EASA licences when other states are, this is to the disadvantage of the UK aviation industry and in conflict with Europan free trade.

No wonder the Brit's like rules!

[IO540]

I would not underestimate the ability of the CAA to create work in the face of EASA. They have had decades of practice and so have the other European CAAs, who are in a similar boat and whose employees get together regularly to work the next anti-EASA-takeover strategy.

Back to the report, it seems to say that see and avoid just doesn't work very well... does this suprise anybody???

TCAS would work but at £15k or so few people are going to install it and even then you are up against the civil liberties brigade who won't carry a transponder.

[astir 8]

The AAIB report states that in addition to the two aircraft involved in the collision, there were four other gliders plus one powered aircraft within 3.5 nm of the collision site. At least two of the gliders seem to have been less than 1 nm away.

Purely out of curiosity, if in theory all those seven aircraft had been fitted with transponders, how would a TCAS unit react to such traffic density?

[IO540]

TCAS would show the other traffic.

What the pilot chooses to do about it is another matter... I suspect in many cases he might continue on the current track and just look out harder :)

[NigelOnDraft]

TCAS, even if you could get a high % in use, has it's limitations in this environment:
It is designed to only give you range & relative altitude
Although most "appear" to give a reasonable bearing, it is not part of the spec, and can be significantly in error. And that is from Airliner installations, I am not sure GA installations would be as good?
It relies on Mode C values being accurate to, say, 100-200'? Whilst again that is not an issue for professional ops, the LAA world has little requirement / experience in ensuring Altimeters and Mode C are calibrated. A TCAS aircraft with it's Mode C in error can cause a midair by itself (almost happened between 2 widebodies in China).
As various accidents / incidents have shown, we have enough trouble with professional crews not strictly adhering to TCAS SOPs. Failure to follow SOPs 100% can make things more hazardous e.g. one pilot does follow the RA, the other tries to avoid visually.
TCAS displays "overload" by design and do not show all traffic. They claim that a target not displayed is still being monitored, and RAs will be generated if required.I am not knocking it - if all GA / gliders etc. had it and fitted it - safety would improve, but it would not be a cheap / perfect / easy answer.

NoD

[IO540]

GA "TCAS" systems don't do RAs; they just show other traffic. My (limited) experience with them, and input from pilots flying with by far the most common system (the Avidyne 600) suggest that the azimuth information is pretty good.

My understanding of CAT TCAS is that an RA is only vertical; you are not supposed to change the heading to avoid something. In the GA context, you are usually pretty significantly performance limited when it comes to climbing (although a zoom climb by maybe 500-1000ft is possible if really pushed, ending up at Vs at the top) so most pilots change their heading to avoid, especially if the target is close.

Occassionally one can also see the tail number of an N-reg plane on the display. EASA has made the emission of most useful data de facto illegal for Euro-reg planes.

I was going to install the 600 system on my TB20 but have resisted, due to the almost total interior stripdown, existing antenna relocation/rewiring, and the resulting downtime of about 6-12 weeks, commencing from when the existing workshop customer stops screaming for his plane to be finished :) I suspect other pilots feel the same, because the cost is not that much on the scale of common avionics upgrades.

All in all, it seems a good working system but it is awfully hard to justify on the midair stats because one only has to climb up to say 3000ft+ and there is practically nobody up there. This is a lot cheaper than £15k... the risk is lower down but a lot of people like to fly low because it is more fun.

I am also certain that discretionary non fitment of transponders correlates strongly with low flying, which is another factor meaning that flying in an area of high traffic density is always going to be risky and technological solutions will be only partial. You fly low and you takes the risk :)

[NigelOnDraft]

Hi IO540...

Thanks for that. I interpreted "TCAS" to be as fitted to airliners, as opposed to a generic system.

In CAT again, the bearing tends to be OK, but not 100%, and the danger comes when people use it for purposes it is not designed for e.g. checking approach is clear on a parallel runway.

The GA systems, if different in design, might have the bearing side designed more strongly?

In practice vertical deviation required need not be a lot, so long as it is not getting further updated by the other traffic (see the LCY incident). I had an RA in a 767 v BizJet and it just told us "Maintain V/S" (which was zero) and it was quite happy with a 500' separation.

As you deduce, it is largely a waste of time fitting anything now for GA since it will only work against a small % of traffic.

NoD

[astir 8]

Thanks for the info on TCAS guys

IO - your statement

"All in all, it seems a good working system but it is awfully hard to justify on the midair stats because one only has to climb up to say 3000ft+ and there is practically nobody up there."

is a horribly dangerous assumption.

a) The Tutor/glider midair was at 4150 feet.

b) Height to a glider pilot is fuel in the tank. e.g. if the thermals were going up to 5000+ feet (rare in the UK but it happens on good days), you would find a lot of gliders in the height band 4000 - 5000+ feet.

[IO540]

The Tutor/glider midair was at 4150 feet.That is extremely rare.

The UK midair stats, post-WW2, are 100% in VMC and nearly all below 1000ft. One recent one was at 1800ft. This one (if 4150ft AGL) is incredibly rare. I know gliders do fly high (up to the base of CU) and thus probably form 99% of the risk above 2000ft, but at the same time they are evidently statistically rare when away from known concentrations.

Are you aware of different stats Astir?

Class G is Class G and nothing can be done about that. And even CAS is not a perfect protector since somebody can bust it, and if they are not Mode C and if the CAS does not touch the ground they will remain undetectable.

IMHO, for most GA TCAS owners, the system addresses a powerful emotional (Russian roulette) issue. Speaking to a non-flying person, or more importantly a non-knowledgeable family member, one of their most alarming realisations is that IMC flight is purely done on chance. So I just tell them there are no known IMC mid-airs in the UK. (And the GA activity level in the rest of Europe is usually far lower or nonexistent).

And flying with TCAS does show you that much if not most traffic presumably visible to a radar controller providing a Traffic Service is not actually reported to you due to controller workload :)

[chrisN]

IO: "The UK midair stats, post-WW2, are 100% in VMC and nearly all below 1000ft." Not strictly true, if you meant to include gliding incidents in that generalisation, although the exceptions do not alter the general thrust of your argument.

I have gliding collision statistics since 1987, and powered aircraft statistics for a recent ten-year period, and know the circumstances of some of each. A lot of the information, however, is not in the public domain.

I also have Airprox data covering a 22 year period. These inevitably are underreported, particularly like-on-like at the low end - e.g., there are no glider on glider or paraglider on paraglider Airprox reports, though I know that there are incidents that fall in the former category and expect there will be in the latter - but we don't report on each other when flying the same sort of thing.

It is certainly true that there is a preponderance of incidents within the circuit area and at heights not dissimilar from circuit heights - that is where most flying things mostly come into proximity.

I think I have been corresponding with your alter ego recently, by e-mail. If that is so, I have an e-mail address for you, and can send you some information privately, if you are interested.

Chris N

[IO540]

Yes, just realised :)

No, I did not include glider-on-glider midairs which I gather are more common.

[astir 8]

It's an interesting thought actually. I've remained puzzled that a very experienced pilot, who presumably realised that he couldn't move his head as much as he once could, should have chosen to do aerobatics in one of the busiest bits of Class G sky in the UK - despite warnings broadcast by the Benson ATC about heavy glider traffic.

And in all fairness to the poor bloke, all the other Tutors flying out of Benson on that day seem to have flown similar flight paths.

I wonder if they also relied on the assumption that the sky is much quieter at 3000+ feet and that midairs are (fortunately) even more unusual at those levels? It's probably a valid assumption - EXCEPT ON A GOOD SOARING DAY.

[astir 8]

I see on the BBC that the inquest has started

[mNav]

BBC News - Drayton crash pilot Flt Lt Mike Blee 'had back condition' (http://www.bbc.co.uk/news/uk-england-oxfordshire-17049294)

[Fraggle_Rock]

How would you propose that gliders are allowed into Brize zone then? Bearing in mind that the Brize zone exists to protect passenger airlines (civil and military) with sometimes up to 260 POB? Surely that is far more important that a few gliders?

If anything has to give stop the gliders flying or put AEF into the Benson visual circuit. Then the kids would still get their flying but not be put into danger.

[A and C]

Why the post now such a long time after the last posting on the subject ?

[Pittsextra]

No idea why this has been pulled forward from 2010 but interesting that no one commented on Astir8's post.

In the end you can complicate this as many ways as you might like to with full medical analysis and potential technical solutions but ultimately poor airmanship on the part of the Tutor pilot is to blame.

He shunted circa 1 hour after warnings from Benson ATC of heavy glider traffic and one would have expected him to have had visual with much of that traffic in the prior flights. Still he chose to continue with what would seem a routine path.

Then one might ask what about the Location and Lookout of his pre-aeros HASELL check?

[Boudreaux Bob]

"The UK midair stats, post-WW2, are 100% in VMC and nearly all below 1000ft."


I seem to recall a Wessex and Harrier that came together IMC and amazingly both landed safely with no loss of life.

Did the two Tornado's that smacked into one another a few years back meet below a 1,000 feet?

[Rod1]

The "all below 1000ft" is not true. Many examples of collisions above this height but it is generally true that the higher you fly the less likely it is. Above 3000ft there are very few. Another example was the crash near Rugeley on 16 December 2007 Between a Luscombe 8E Silvaire and a Pacific Aerospace 750XL which happened at around 1500ft AGL. The two people in the Luscombe were killed, the 750XL landed at East Mids.

Rod1

[mad_jock]

http://www.airproxboard.org.uk/docs/423/BOOK%2028.pdf

See if this works

The front section has a good set of statistics for the various danger zones for GA.

Also that not taking a basic or traffic service means less airprox's