With a lot of experience it is possible to differentiate between certain types, but great care is needed. Sound Sound is very often the first indication that an aircraft or helicopter is approaching. Weather effects and the varied abilities of human ears can however make sound very misleading. It may appear to come from completely the wrong quarter, causing the observer to miss the approaching aircraft altogether. With fast aircraft, the subject may be well ahead of its noise.
Sound is nevertheless important and certain basic facts can be gleaned from it.
It is important to both watch and listen in order to associate sound with a particular type. A great deal of practice is needed before making snap judgements on sound alone, and even then there is a higher chance of error. Teaching Recognition Teaching aircraft recognition, whether in the services or a club, is an exacting task calling for method, efficiency and, above all, background knowledge of the subject. The ace spotter who can recognise anything does not necessarily make a good instructor, as he may be too far removed from the novice's problems. Sometimes a film can provide excellent material, though a particular view cannot be shown again as quickly as with the other devices.