This was the British plan for the operational use of the Long Aerial Mine, a contact-fused mine suspended from a parachute by a long cable and designed to be dropped in large numbers into the path of German bomber formations (1940/6 December 1941).
From top to bottom, the LAM comprised a medium-sized parachute, a 1-lb (0.45-kg) explosive charge, 2,000 ft (610 m) of piano wire, and a parachute in a container. The dropping aircraft were six obsolete Handley Page Harrow bomber transports of No. 420 Flight, which was formed in 29 September 1940 and on 7 December of the same year became No. 93 Squadron with one and two flights of Vickers Wellington and Douglas Havoc aircraft respectively.
Each Harrow could carry 120 LAMs and, cruising at an altitude of 20,000 ft (6095 m), released its LAMs at 200-ft (60-m) intervals at right angles to the approaching German bomber stream. The mines thus formed a curtain, some 4.5 miles (7.25 km) long and about 2,700 ft (825 m) deep, across the bomber streamís line of flight, and descended under their upper parachutes at the rate of about 1,000 ft (305 m) per minute. If a bomber struck a wire, the shock caused the release of the upper parachute and deployed the lower parachute, which then dragged the explosive charge down onto the bomber, where it detonated on impact.
It is believed that LAM-equipped Harrow aircraft destroyed six German bombers, but the scheme was scarcely practical and No. 93 Squadron was disbanded on 6 December 1941.