Instrument: Airborne Vertical Atmospheric Profiling System (AVAPS)

The Airborne Vertical Atmospheric Profiling System (AVAPS), also known as the AVAPS Dropsonde System, is a key atmospheric instrument that measures high resolution vertical profiles of ambient temperature, pressure, humidity, wind speed and wind direction. Measurements are taken by a parachuted GPS dropsonde that is launched from the aircraft and descends to the surface.The dropsonde is composed of a small electronic circuit board, sensors, and a battery housed in a cardboard tube with a parachute. The inner electronic components of the dropsonde consist of precision temperature, pressure and humidity sensors, low powered telemetry transmitter, GPS receiver, and a microprocessor. The parachute deploys from the top of the sonde within seconds of being released from the aircraft. The square-cone parachute is very stable during the descent, reducing or eliminating any pendulum motion of the dropsonde. As the dropsonde descends, it continuously measures the atmosphere from the release altitude to the Earth’s surface. Measurements are transmitted via a 400-406 MHz meteorological band telemetry link to the receiving system onboard the aircraft.

The AVAPS system has been installed in numerous aircraft.