South Korea planned to resume flights with its Boeing F-15Ks on 21 August after concluding that the 7 June loss of an aircraft and its two crew was caused by the pilots' g-induced loss of consciousness (G-LOC). All F-15K pilots have been retrained in aerophysiology, says the South Korean air force, which plans to enhance its biological training structure and introduce G-LOC training equipment.
G-LOC, which can occur when the body is subject to acceleration sufficient to force blood away from the brain, can be prevented through anti-g straining by the pilot. The two-seat F-15K crashed during air combat training after the crew became too focused on manoeuvring into the best position for an attack, lost height and suffered G-LOC while recovering altitude, the air force believes.
A rash of G-LOC incidents which followed the US Air Force's introduction of the F-15 and Lockheed Martin F-16 led to aeromedical studies that concluded the best prevention was training, particularly for pilots new to the aircraft. Studies of USAF mishaps in the 1980s and 1990s showed the incidence of G-LOC was low, with no fatalities in two-crew aircraft, making the Korean crash unusual.
The F-15K crashed in the East Sea off Pohang during a night-time training mission. The air force says it was able to recover 75% of the debris, including the enhanced crash-survivable memory unit, caution/warning panel, oxygen adjuster, standby attitude director indicator and parts of the engines. The digital video recorder that records the cockpit displays was recovered, but the memory chip was severely damaged and the data unrecoverable.
The air force says the F-15K left Daegu airbase at 19:42. The aircraft discharged simulated air-to-air weapons at 20:11 but, while manoeuvring to respond to an opponent's attack, the crew sent a "knock it off" signal at an altitude of 11,000ft (3,350m) - the aircraft crashing 16s later, at 20:12:19.
"After executing air-to-air attacks on enemy aircraft, the pilots avoided the enemy's counter- attacks and were so focused on the tactical movements when taking an advantageous position for later attack, that they fell too deep and suffered from G-LOC while recovering from the [low] altitude," says the air force.