I commence my general remarks with a preamble: I am a glider pilot, I am not opposed to transponders for gliders under all circumstances, but I believe that they should be a voluntarily fit at present. They cannot be mandatory. The reasons are well rehearsed and I won’t repeat them in this post. But an anecdote, for those tempted to think they are a panacea: when flying between Cambridge and Suffolk in the Lakenheath area, I heard the pilot of a transponder-equipped aircraft near Bury St Edmunds making repeated efforts for his squawk to be seen, and Lakenheath could see nothing of him, on either primary or secondary radar. So please don’t think that having a transponder automatically makes you visible to air traffic control. Like any other machine, they are not 100% reliable.
We could go on all day about differences in philosophy as to what is acceptable risk, and what is not, in somebody else's chosen field of aviation. I have long given up any hope of convincing power pilots about aspects of gliding that they don't involve themselves in. In the end, however, I do believe that the statistics are a fair reflection of the relative dangers. In the past four decades, I know of only two glider collisions in cloud, and probably two more, both fatal, at or close to cloud base when radio for separation was not being used. By contrast, instances of powered aircraft hitting the ground, and/or each other, are rather more numerous. I know where I think our dangers, and yours, seem to be greater.
It seems, however, to be a feature of the human condition to fear more a risk with elements beyond our own control than those we think we can avoid by our superior expertise.
What kills most in the power GA world? CFIT and loss of control in IMC?
This is from the CAA Safety Sense leaflet- Airmanship:
a. There is an average of one fatal GA accident a month in the United Kingdom.
b. The main fatal accident causes during the last 20 years have been:
• continued flight into bad weather, including impact with high ground and loss of control in IMC
• loss of control in visual met conditions, including stall/spin
• low aerobatics and low flying
• mid-air collisions (sometimes each pilot knew the other was there)
• runway too short for the aircraft’s weight or performance
• colliding with obstacles, perhaps being too low on the approach
What are people here most worried about? Collision with gliders.
I have seen two sorts of data. 1 – actual fatal collisions, glider-glider and glider-power. The former outnumber the latter by about 10 to 1. 2 – airprox data for GA/glider incidents. The vast majority are within or close to the gliding site circuit.
I don’t have data for power/power collisions (does anybody else?), but I believe there are more than the four power-glider collisions in the last 40 years, all in VMC:
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8 March 1981. (AAIB report 7/81). Blanik/PA28. The PA28 was doing an Overhead Join onto Cranwell Main. It flew into the glider which was being launched. 2 glider pilots killed.
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1984: A Rockwell Commander flew straight into the back of a glider flying straight, between thermals, that it caught up. The glider pilot was killed. The Rockwell and occupants survived. The only case I know of in the UK where it was not near a gliding club.
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(Dunno the date, but years ago) Over Farnborough airfield between a glider from the Farnborough gliding club and a light aircraft from Blackbushe. The Astir pilot baled out and landed safely on the airfield. The power pilot flew back to Blackbushe with his pupil instead .
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May 1996 Grumman.
A Grumman light single flew into a Ka13 from behind, sliced the outboard couple of feet off the Ka13's wing tip with its' rudder. The Ka13 landed safely at its nearby base (Haddenham), the Grumman went into a spiral dive and struck the ground very steeply at about 200 knots, the single occupant was killed.
The collision happened in the open FIR, in good visibility, well clear of cloud. From the heading of the Grumman it seemed quite likely it was tracking towards a nearby VOR.
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(I have omitted one or two collisions between gliders and tugs operating from the same gliding site – they were nothing to do with IMC, and nothing to do with general GA/glider collision risks. I know of one that was fatal.)
Glider/power collisions in IMC are zero so far, for at least two probable reasons, IMHO.
One is the much rehearsed “big sky, little bullet”, as mentioned by others.
The other is that glider IMC flights are relatively few, and those few are almost all in summer cumulus (and of course only in Class G), not continuous stratus etc. which is what I suspect most often causes power to be in IMC.
With glider cloud flying at least we have a procedure that is usually sufficient to ensure that there are not two gliders in the same cloud at the same height at the same time. My personal opinion is that it is probably more effective than, e.g., the see and avoid manoeuvres, which aerobatic pilots (power and gliding), to name just one field, indulge in prior to such exercises.
Gliders that cloud fly normally call out on 130.4. It is not a legal requirement, but most conform. Power pilots could listen out on that, but I believe most don't. That is their choice. As I have written before, “ . . . if [power GA] wishes to fly in cloud . . . when gliders may be in cloud (i.e. on days of separated summer cumulus, not in stratus which we can’t get into), I recommend listening out on 130.4 before entering such cumulus clouds. Of course, you don't have to do, but in my view it would be advisable in those circumstances.”
Power in IFR in class G is taking that risk. They also take the risk of colliding with each other - there is no one frequency that all power without exception will be using in class G IMC, and there may be some non-radio power anyway (just as some cloud-flying gliders may be non-radio). That's how things developed here, and there is no significant accident rate from these causes - unlike VMC/VFR where there are more frequent collisions between G/G (about 1 fatal every year), G/P (one every 10 years) and P/P (something in between?).
If you are still reading this long missive, thanks for your patience. Finally, may I point out that the present discussion arose from a “miss” between two aircraft both entitled to be where they were. Last time I got involved in such a thread, about the perceived need by power pilots for gliders to carry transponders and/or not to fly in cloud anyway, was triggered by a collision between two powered aircraft, in VMC, at low level, and both in touch with ATC. It is typical that powered aircraft collide most often with each other and very rarely with gliders.
So, where are the real risks? I know what I think.
Best wishes for your safe flying – Chris N.
[edit - spelling corrected]