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Originally Posted by c5000052
(Post 10471051)
I suppose take off distance on grass with sr22 is close to limits at this airfield.
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I was meaning distance to reach 50 feet on grass. Anyway, we may know from the pilot at some stage. Would be useful lesson for all of us.
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Daily Mail report of the rescue with photos:
https://www.dailymail.co.uk/news/art...road-halt.html |
the additional dangers posed by the ballistic parachute system. Are you referring to the explosive charge? I can see that this is relevent but I have never seen this specific hazard detailed before. |
ARFF Considerations Working Around Ballistic Recovery Parachutes | ARFF Resource
I'm not too skilled in adding attachments but a suitable Google search will no doubt point you in the right direction. And this is aimed at professionals, not innocent bystanders.... |
So obvious when you think about it, but to non GA bystanders I suggest a real danger. Must admit it would not (until-now) have been uppermost in my mind seeing a GA aircraft down. It would be now. There will have to be a general awareness of the possibility of high explosives in the roof of a ‘downed’ GAAircraft. |
Originally Posted by funfly
(Post 10471430)
So obvious when you think about it, but to non GA bystanders I suggest a real danger. Must admit it would not (until-now) have been uppermost in my mind seeing a GA aircraft down. It would be now. There will have to be a general awareness of the possibility of high explosives in the roof of a ‘downed’ GAAircraft. |
If you’re keen to drag pax out of an upside down cab that’s probably full of fuel then I think the solid fuel ballistic parachute probably comes in at the PXR phase (Debrief) of the incident. |
A solid fuel rocket is not an explosive, let alone a high explosive.
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Three days in nobody has been blamed or maligned yet .. PPRuNe losing the plot ?
OK genuine question .. What actually happened to put the aeroplane from a runway that looks to be parallel to the A40 (on whichever side) onto the road ? was it taking off or landing ? undershoot or overshoot ? engine failure ? Thought all these things would have been debated by now |
Well the Daily Mail says here (https://www.dailymail.co.uk/news/art...road-halt.html ) that it hit some "overhead train lines". I'm sure those weren't shown on the charts so that's got to be reason enough for the crash, has it not?!
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Typical DM, they should have checked and they would have known that the railway line does not have overhead electrical lines. |
The power line that was hit is a typical 3 phase line feeding farm builduings. It crosses the runway centreline, A40 and railway at 90 degrees one field (150 metres) beyond the 33 threshold. Poles are about 25 ft high. The line is clearly marked on OS maps.
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The hazard posed to people by the pyrotechnics in the ballistic parachute cooking off in a fire are interesting , during the Vietnam war there was a huge fire on the USS Forristal, an aircraft carrier, while the reason for the fire was the initiation of a rocket by an EMP but the consequences of having old WW2 bombs on the deck ( used for financal reasons ) made things far worse as these cooked off quickly when exposed to fire giving the fire crew very little time to react, modern ordinance is much more resistant to fire and gives fire crews time to put out the fire and cool the area. I would be very interested to know the fire resistant standards applied to the ballistic parachute pyrotechnic. |
Originally Posted by Whopity
(Post 10472166)
The power line that was hit is a typical 3 phase line feeding farm builduings. It crosses the runway centreline, A40 and railway at 90 degrees one field (150 metres) beyond the 33 threshold. Poles are about 25 ft high. The line is clearly marked on OS maps.
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It's clearly marked on the 1:50k, but not on the 1:25k at least not on the online Streetmap version. They are also on some aeronautical charts - I don't have one to hand, suspect it's the 1:250k not the 1:500k. Could well be wrong about that though!.
Streetmap.co.uk - Map of 331674,210680 |
Originally Posted by Dave Gittins
(Post 10471843)
OK genuine question .. What actually happened to put the aeroplane from a runway that looks to be parallel to the A40 (on whichever side) onto the road ? was it taking off or landing ? undershoot or overshoot ? engine failure ? Thought all these things would have been debated by now
A later BBC report (https://www.bbc.co.uk/news/uk-wales-48251547) shows that the Cirrus had previously landed at the private strip alongside the A40 to pick up two pax. It had just taken off when the accident happened. |
and in his earlier post he said it was trying to land .. and there seems to be some mix up about a railway track with overhead lines, apparently brought down and run over by a train.
My point is it seems hardly crystal clear what happened and I'd have expected some speculation as to why. Surprisingly I'd have expected an email from AAIB saying they had dispatched a team but nothing from them, nothing on their website either. |
From the position of the accident site it looks as if the take off was from 15. The runway is reported to have a significant "hump" which would substantially affect t/o run. Additionally the wind in the area at the time appears to have been predominantly northerly 5-7kts but it is impossible to be certain due to local effects, valley etc. However that seems likely.
So, take off downwind on grass, fairly heavy and with an up-gradient on at least part of it? Plus the terrain is rising gently in that direction. Of course we don't know the fuel state but with three adults on board it's likely to have been well towards the higher end. I'd foresee difficulties heading off under those (speculative) conditions. The telling thing of course is the distance to clear a 50ft obstacle which is what a 30ft pole with a 20ft terrain rise over that distance might well be... I've looked at the performance tables and made a few assumptions about TOW etc and the numbers come out remarkably close to 50ft right about where those wires are. A bit rough and ready I know but might be an explanation. |
The attached may be helpful in order to provide a fuller picture of what is involved:
Jack |
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