In early 1940, Alan Blumlein and his team at the EMI Central Research Labs began work on the technology behind the Capacitance Altimeter. This device works by measuring the differences in charge between a low lying aircraft and the charge at earth’s surface, therefore enabling aircraft and other vehicles to fly at night and in cloudy conditions.

In the summer of 1940, the first test flights using this new technology were conducted in Wellington, Whitley, Halifax, Stirling and Lancaster bombers. The development of the Capacitance Altimeter made ‘blind landing’ (landing at night or in foggy/cloudy/rainy conditions) a reality.

During the Second World War it was used extensively in the armed forces for low-level bombing and torpedo releases, mine laying and parachute dropping. The design and technology developed in this product were significant factors in shortening the length of the Second World War and are still in use today.