The Vaisala Dropsonde RD93 is a general-purpose dropsonde for high-altitude deployment from a variety of aircraft. Slowed in its descent through the atmosphere by a special parachute, the RD93 measures the atmospheric profiles of pressure, temperature, relative humidity and wind from the point of launch to the ground.

The RD93 transmits meteorological data via a 400 MHz meteorological band telemetry link to the receiving system onboard the aircraft. The receiving system can be the Vaisala AVAPS receiving system, which tracks up to four RD93s simultaneously, or the Vaisala AVAPS Lite receiving system, which tracks one RD93 at a time.

The onboard GPS receiver tracks the dropsonde’s horizontal movement as it is borne by the wind. The Atmospheric Technology Division (ATD) of the National Center of Atmospheric Research (NCAR) developed the hardware and software for the Vaisala Dropsonde RD93, the Vaisala AVAPS and the Vaisala AVAPS Lite. Production of the RD93 and AVAPS systems is licensed to Vaisala Inc., USA.