Have you ever watched an airplane flying overhead and wondered where it was going and wished you could listen to the Air Traffic Controller (ATC) telling the pilot what to do? Well with todays modern techonology you can do just that by buying a radio scanner. They can cost anything from £50 for a cheap and simple 'analogue' (move a dial to alter the waveband) receiver to around £350+ for a digital (use a keypad to type in the frequency you want) memory enabled one.
My first scanner was actually an old Tandy (Radioshack) radio which had a telescopic aerial and a dial for maually scanning the frequencies. I could only pick up Farnborough LARS which is a few miles away from me and the odd airliner when overhead. I then started taking flying lessons and visiting airshows and got tired of manually scanning, and only guessing what frequency I was listening to so I visited various web pages and got a 'digital'scanner. I got the GRE PSR-244 receiver from Javiation (www.javiation.co.uk) for £100 which is a simple 'digital' scanner with 50 memory settings and is far more accurate and has a better range than the little Tandy receiver. The scanner will automatically scan the memories or a frequency range and lock onto a broadcast. When you have a frequency you can proram it into a memory so you can find it later, for example I have the Farnborough LARS frequency (125.250MHz) on channel 1, so I can simply press the 1 button to quickly get it. I currently use the scanner at home using the power supply unit but you can run it off batteries (it can even recharge the rechargable batteries) and use it at airshows. It has a handy belt hook and a short antenna which makes it handy for portable use, and the LCD display easily shows what frequency you are listening to. It has a frequency range of:
Using these 4 bands it is possible to pick up all sorts of radio traffic, not just aircraft but taxis, company radios and the emergency services, BUT, it is illegal to listen to these broadcasts as they are private communications. The authorities 'allow' air band listening as it poses no threat (go to any airshow and you will see hundreds of scanners in use), but obviously transmitting on these frequencies is incredibly stupid & dangerous. I have heard of 2 incidents (USA & Japan) where airliners received false directions from someone with a transmitter. The results had these airliners acted on these instructions could have been horrific, thankfully the pilots ignored them and contacted the real ATC.
There are more advanced scanners which can receive CB, Ham (Amateur), Military Airband and even space communications (NASA & Mir) which can scan the whole wavelength from 0.25MHz to 1300MHz, and many can now be controlled by computer, (cost is about £300+, look at the AOR models).
The file scanner_database.zip contains a (Mac) Filemaker Pro 3 file containing the airband frequencies and allows you to store your own information. There are a number of scanner sites out there if you want more information there are also some good books such as David J.Smith's "Air band Radio Handbook" which you can get from Transair