Mid-air collisions:
In principle the glider pilot has a smaller probability of having a mid-air collison when flying than a collision when driving because flight occurs in 3 dimension whereas the car is constrained to move in 2 dimensions. However this advantage is lost because pilots often fail to maintain a continuous scan for other aircraft while they are distracted reading maps, or adjusting instruments. In addition, aircraft typically converge at higher velocities and are difficult to spot because they approach from 3 dimensions. This is especially true of gliders that subtend a tiny solid angle looking along the fuselage axis. Since mid-air collisions are relatively rare the pilot can be seduced into complacency and into failing to continuously scan for traffic. The following examples of recent glider collisions illustrate that mid-air collisions continue to be an important danger when gliding.
June 7 2012: Air Sailing, NV: A Centrair Pegasus, N101LV, owned by the Bay Area Soaring Associates, collided with a Standard Cirrus N943SB at 6800msl over a ridge where 6 gliders were thermal and ridge soaring. The Cirrus lost 80% of the left aileron while the Pegasus lost 2 ft of the right wing tip and part of the right aileron. Tbe links provide pilot reports of this collision and a photograph of the damage to the Pegasus wingtip. Note the gorgeous lenticular cloud shown in the background of this picture of the damaged wing. This collision occurred at a thermal camp for less experienced pilots under circumstances similar to what we experience when soaring the ridge at Dansville.
June 15, 2010: Parowan, UT: At the 2010 US Sports Class National competition ASH26E, N455S, collided with Schempp Hirth Ventus 2CT, N514TW at 13500msl. The Ventus suffered minial damage whereas the ASH26E lost the outer 3ft of the left wing. Fortunately both pilots were unhurt and were able to land back at Parowan.
February 6, 2010:, Boulder CO: A Cirrus aircraft ran into a Pawnee towing a Schweizer 2-32 over Boulder. The 2 Cirrus occupants plus the Pawnee pilot were killed. Fortunately the Glider pilot released from the tow on seeing the collision so he and his two passengers landed safely.
28 November 2009, Cazy Creek, CA: An ASW27 collided with the Pawnee tow plane as they turned onto final and both pilots were killed. Like Dansville, the power traffic used a left-hand pattern while the glider traffic a right-hand pattern. Prior to the head-on collision they did not communicate nor see each other.
14 June 2009 Oxfordshire: A RAF Tutor training aircraft ran into a glider. The glider pilot parachuted to safety, the 2 power pilots were killed.
15 January 2009; New York: An Airbus 320 collided with a flock of geese and ditched in the Hudson. Sully the pilot was a glider pilot.
2006 Minden CA: A descending private jet collided with a thermalling ASG29. The glider pilot parachuted to safety while the jet made a safe emergency landing.
Keep your eyeballs busy scanning for other aircraft. Rely on the vario audio plus tactile senses to thermal.
FLARM:
In Europe the glider community has widely adopted use of the FARM anti-collision system and it has been reported recently that France intends to make use of FLARM mandatory for all gliders and towplanes. The US version of FLARM has undergone testing at several contests in the US during 2012 and there is widespread support for its adoption for soaring contests. The above examples of mid-air collisions illustrate that mid-air collisions are a widespread problem that is not restricted to only competition flying.