speed, cockpit placement, colour scheme or special equipment that changes the silhouette of the aircraft. Taken together these traits will enable the identification of an aircraft. If the observer is familiar with the airfield being used by the aircraft and its normal traffic patterns, he or she is more likely to leap quickly to a decision about the aircraft's identity – they may have seen the same type of aircraft from the same angle many times. This is particularly prevalent if the aircraft spotter is spotting commercial aircraft, operated by airlines that have a limited fleet. Spotters use equipment such as ADS-B decoders to track the movements of aircraft. The two most famous devices used are the AirNav Systems RadarBox and Kinetic Avionics SBS series. Both of them read and process the radar data and show the movements on a computer screen. Another tool that spotters can use are apps such as FlightRadar24 or Flightaware, where they can look at arrival and departure schedules and track the location of aircraft that have their transponder on. Most of the decoders also allow the exporting of logs from a certain route or airport. Spotting styles Some spotters will note and compile the markings, a national insignia or airline livery or logo, a squadron badge or code letters in the case of a military aircraft. Published manuals allow more information to be deduced, such as the delivery date or the manufacturer's construction number. Camouflage markings differ, depending on the surroundings in which that aircraft is expected to operate. In general, most spotters attempt to see as many aircraft of a given type, a particular airline, or a particular subset of aircraft such as business jets, commercial airliners, military and/or general aviation aircraft. Some spotters attempt to see every airframe and are known as "frame spotters." Others are keen to see every registration worn by each aircraft. Ancillary activities might include listening-in to air traffic control transmissions (using radio scanners, where that is legal), liaising with other "spotters" to clear up uncertainties as to what aircraft have been seen at specific times or in particular places. Several internet mailing list groups have been formed to help communicate aircraft seen at airports, queries and anomalies. These groups can cater to certain regions, certain aircraft types, or may appeal to a wider audience. Many of these groups originated from the original Oxford.vax group which pioneered this