The UK’s Air Accidents Investigation Branch (AAIB) has released a further update on its investigation into the August 23 ditching of a Eurocopter AS332L2 Super Puma off the Shetlands islands. The latest document reveals that during the approach the pilot’s attention was drawn several times to a too-low-height warning.
Aboard the CHC Scotia-operated helicopter, the second warning came when the copilot advised, at 2.2 nm from the airport at 560 feet, that the target altitude at 1 nm was 390 feet. The pilot answered that he was reducing the rate of descent, which decreased to 500 fpm from 700 fpm.
However, the aircraft’s 74-knot airspeed was still too fast for the descent to meet the target. An automated alert could be heard on the cockpit voice recorder at 300 feet, the report said.
During the final stages of the flight, the AAIB said, the helicopter entered vortex-ring state, a condition where the main rotor’s effectiveness is significantly reduced. This was due to the combination of the nose-high attitude, low airspeed, high descent rate and high power.
The AAIB’s ongoing investigation will focus on how the pilots monitored instruments during the approach.