TV signals used to track aircraft as alternative to radar

[Ian K]

Research carried out by the air traffic control provider Nats and its partners suggests that existing TV signals could be used to track aircraft, providing a cheaper alternative to radar

http://www.bbc.co.uk/news/technology-33063353

[mezoo]

In a similar way aircraft are being used by radio amateurs to increase their range.

http://www.nitehawk.com/w3sz/AircraftScatter.htm
http://www.g4ztr.co.uk/amateur-radio/aircraft-reflection/
http://www.rtl-sdr.com/fingerprinting-aircraft-with-aircraft-scatter/

Just google "Aircraft scatter"