The first officer raised the nose to 14 degrees to reduce the airspeed from 165 kn to 153 kn, the speed specified in the emergency procedure for engine failure during takeoff.
He reacted quickly, but he did precisely the wrong thing: he jerked back on the yoke, lifting the plane's nose and reducing its airspeed, instead of pushing the yoke forward to gain velocity.
But the helicopter's airspeed reduced to below 80 knots, unobserved by the crew.
Initially, this outflow causes a headwind that increases airspeed, which normally causes a pilot to reduce engine power if they are unaware of the wind shear.
Full or partial compensation reduces drift instantaneously but may potentially reduce migration speed: because the bird no longer dedicates its entire airspeed to travel along the preferred direction, its transport cost (mechanical flight energy per unit distance) will be higher.
If you're descending for a landing at an airport further away, reduce throttle to 2000 RPM to descend while maintaining a higher airspeed.
An interim report published by the AAIB said that, as the helicopter approached to within 2.3 nautical miles of the airport, the commander noted that its airspeed had reduced to 80 knots.
As the aircraft passes into the region of the downdraft, the localized headwind diminishes, reducing the aircraft's airspeed and increasing its sink rate.
At this time, the helicopter's airspeed was only 35 knots and reducing.
Moreover, by including climate homogeneity in the building design process, the occurrence of high airspeeds in specific regions of a building can be reduced during windy outdoor conditions, thereby reducing the cold-stressing of animals in these regions.
