When an Air China Cargo 747-400F lined up for departure, its engines turned loose runway ice into airborne projectiles.
The reason comes down to physics.
A fully loaded 747-400F powered by Pratt & Whitney PW4000 or GE CF6 engines produces enormous exhaust velocity. At takeoff power, jet blast near the nozzle can exceed 400 knots, with exhaust temperatures above 140°C. Even hundreds of feet behind the aircraft, the airflow is still powerful enough to move heavy objects.
When that exhaust hits cracked runway ice or frozen snow along the runway shoulders, it can get underneath the surface and lift large sheets into the air.
From a maintenance and operations standpoint, this is a foreign object debris (FOD) hazard with a winter twist. Runway sweepers may clear the main operating surface, but a widebody's engines and wings extend far beyond the centerline, exposing ice and debris at the edges.
Winter operations don't just mean keeping the runway centerline clear. If the shoulders and surrounding surfaces are neglected, a heavy aircraft can turn them into a source of dangerous FOD for itself and every aircraft that follows.
WATCH: Air China Cargo Boeing 747-400F's jet blast sends large ice blocks flying, leading to a runway closure at Schiphol Airport in February 2021.
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