Civilian and military airplane “spotters” can convert themselves into mobile listening stations with the aid of a portable plane detector designed for use where more elaborate units are not available. Sound of an approaching plane is picked up by a microphone centered in a parabolic concentrator worn as a headpiece. When a low-pitched sound is heard in the earphones, the listener turns his body until the sound is at its loudest, in which position he will be facing its source and can focus his binoculars swiftly and accurately on the aircraft for identification. The amplifier, batteries and accessories are housed in a carrying case slung over the watcher’s shoulder. Three miniature tubes are used in the amplifier. Filters eliminate noises other than those created by airplanes. Volume can be controlled to suit the operator.