See and Avoid

[mary meagher]

On another thread is mentioned a midair collision in Canada on 30 June, between a glider and a Cessna 150; four fatalities .....The Canadian Safety Board will no doubt issue a comprehensive report in due course.

Goes on to say that midair collision is one of four most usual cause of fatal accidents in gliders. I know the British Gliding Association does keep track of these accidents in the UK, is this done for all of Europe as well? and the rest of the world?

Gliders make a habit of flying very close to each other in thermals, eyes on stalks, and head swiveling to keep track of those nearby, but the pilots do wear parachutes. The midair between a Tutor power plane and a glider near Didcot a few years back, the problem was the Tutor pilot could not because of a physical problem turn his head well enough to see and avoid, so hit the glider from behind. Another midair near Aylesbury between a K13 glider and a power plane also seemed to have occured in the same way, the power pilot didn't see the glider and hit it from behind.

A midair can spoil your entire day.

[Maoraigh1]

Flying solo near a glider site yesterday, not looking at instruments. Nothing in sight. Asked to change squawk. Did so. Still nothing in sight.
I hope nothing passed near me in the time it took to rotate a single Trig number, or was missed in the quick glance before moving to the next number.:(

[sharpend]

The skies are getting crowded. My solutions:

1. Look out more.
2. Look also with your ears!
3. Fly aeroplanes with big windows.. Bulldogs are great!
4. Get TCAS.
5. If an aeroplane is maintaining a steady angle to you, it will hit you.

[Mariner9]

Sad fact is gliders can be difficult to spot. Better and wider usage of Flarm/tcas and the like on all aircraft would probably do more to reduce the chance of collision than any amount of head-swivelling training.

Can glider pilots hear powered aircraft approaching Mary?

[tmmorris]

In the Didcot Tutor/glider midair, the glider pilot was on record as saying he heard the Tutor, but only a couple of seconds before impact. (This was one reason for his successful bale-out, as he was mentally prepared.) So yes, but not usefully so, in this case. Mary will have better knowledge, though.

Tim

[Pittsextra]

The midair between a Tutor power plane and a glider near Didcot a few years back, the problem was the Tutor pilot could not because of a physical problem turn his head well enough to see and avoid, so hit the glider from behind.

Lets be frank. That crash was just complete idiocy on the part of the Tutor pilot. That accident was preventable at the pre-flight planning stage.

[mary meagher]

I do know you can clearly hear the engine of the towplane that is pulling your glider up; but as I do look out constantly, especially when entering or leaving a turn, I have managed to see the other guy before there was any chance of hearing him.

Interesting though, the first warning I have had of a glider being rather near was noticing an extra shadow on the ground......this at circuit height.

[cumulusrider]

Yes you can hear other aircraft from a glider, particularly if it is something like a chinnook. Unfortunately when flying a glider I have difficulty judging the direction. Anyone else have this problem?

[JW411]

Fifty years ago I was a young co-pilot on Argosys at Benson. I was also a keen member of the Chilterns Gliding Club. Benson was also the home of The Queen's Flight.

We didn't have radios then but we had a strict rule that if ATC fired off a red flare, we had to make a decision. If we were soaring and able to clear the circuit and stay airborne then we could continue, otherwise we had to come in and land.

One beautiful summers afternoon I was soaring with a pupil in an open cockpit Slingsby T-21 when up came the red flare. We were now south of the airfield and on top of the Chilterns so we stayed airborne.

Next thing was the noise of a helicopter. It got louder and louder and it didn't matter which way I turned, I couldn't see it. Eventually it sounded like it was right in the open cockpit with us.

Eventually, a Royal Wessex appeared alongside and, with a wave, it went off to land at Benson. It was Ron K. (who was Phillip's helicopter pilot) on his way back from Windsor Castle and he decided to have some fun!

The Navy always were a bit different!

[John R81]

The clue is there - 'see' and avoid. Do all you can to help others see you.

Happy flying

[abgd]

one of four most usual cause of fatal accidents in gliders

But only the 9th most common cause of accidents in GA. Unfortunately looking out of the window is only of limited usefulness though:

http://www.atsb.gov.au/media/4050593/limit_see_avoid.pdf

The exception being when you're in the circuit, and traffic is likely to be in a much more limited range of the sky.

We all know from experience that when we do see another aircraft out there in the cruise, often as not you catch sight of it at the last moment, then.. whoosh - it's gone before you could possibly have taken avoiding action. Or ATC asks you to 'report traffic in sight' and you can't find it even though you know more or less where to look.

[mary meagher]

A careful reading of the Australian assessment of See and Avoid as a method of avoiding mid air collision must give rise to concern that as only 50 percent of the time one is looking outside the cockpit of your average airliner, and probably due to limitation of the eyeball and brain of your average pilot, its not much use bothering to look out at all at all.

So lets just bumble along with our eyes shut, right?

[abgd]

I checked the link to make sure I'd put up the right one...

Here's the bit that really stands out for me:

FAA Advisory Circular 90-48 C recommends scanning the entire
visual field outside the cockpit with eye movements of ten degrees
or less to en sure detection of conflicting traffic. The FAA
estimates that around one second is required at each fixation. So to
scan an area 180 degrees horizontal and thirty degrees vertical
could take fifty four fixations at one second each = 54 seconds.
Not only is this an impracticable task for most pilots, but the scene
would have changed before the pilot had finished the scan.

Harris (1979) presents even more pessimistic hypothetical calculations.
He estimates that under certain conditions, the search of an area 180
degrees by thirty degrees would require 2700
individual fixations and take around fifteen minutes


I'm not advocating keeping your eyes in the cockpit the entire time.
Just pointing out that doing so is hardly a guarantee of avoiding
collisions. The idiot pilot who didn't see you may well be keeping just
as good a lookout as you are!

In practical terms, the message I take home from this is that the
most important means you can use to avoid collisions is to rely
on other strategies such as the semicircular rule over MSA,
'random' cruising altitudes below and avoiding busy areas such
as gliding sites or nice-looking ridges. And in the circuit there's
probably more to be gained from looking in the directions you're
expecting aircraft to come from, rather than trying to scan for
random people passing through which would distract you from
the former...