When spotting aircraft observers notice the key attributes of an aircraft. They may notice a distinctive noise from its engine or the number of vapour trails it is leaving. They will assess the size of the aircraft and the number, type and position of its engines. Another clue is the position of wings relative to the fuselage and the degree to which they are swept rearwards. Are the wings above the fuselage, below it, or fixed at midpoint, perhaps it is a biplane or triplane. The position of the tailplane relative to the fin(s) and the shape of the fin are also clues to its type. If it is an antique or light aircraft it might have a tail wheel. Some aircraft types have a fixed undercarriage while others have retractable wheels.
Other features include the speed, cockpit placement, colour scheme or special equipment that changes the silhouette of the aircraft. Taken together these clues 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.
Some spotters will note and compile the markings, a national insignia or airline livery or logo perhaps, 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.
Ancillary activities might include listening-in to air traffic 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.
The hobbyist might travel long distances to visit a different airport from their usual one, to see an unusual aircraft or to view the remains of aircraft withdrawn from use. Some aircraft may eventually be placed in the care of museums (see Aviation archaeology) – or perhaps be cannibalised in order to repair a similar aircraft already preserved.
Some spotters are competitive and may get a thrill from seeing all the aircraft of a particular operator, military or civil. Aircraft registrations can be found in serial books, such as Military Aircraft Serial Review, or magazines, like Scramble.