The Mk 4.3 Aerosonde is a small, autonomous, high performance, high endurance, expeditionary unmanned aerial system. It is powered by a high-performance reciprocating engine and has a broad operational flight
envelope. The air vehicle and its core systems are incredibly robust, with mission success of supporting flights into the eye of several different hurricanes and tropical storms. In August 1998, an Aerosonde air vehicle completed the first transatlantic flight ever achieved by a UAV. In 26 hours and 45 minutes, it flew the 1,765 n miles (3,270 km; 2,032 miles) separating Newfoundland, Canada, and the Outer Hebrides, UK, under autonomous guidance by autopilot and GPS. Only 4 kg (8.8 lb) of its 5 kg (11.0 lb) fuel load was consumed.

The Mk 4.3 Aerosonde AV is extremely versatile; with several payloads varying widely in specification, performance and capability having already been integrated for a variety of customers. The list of integrated mission payloads consist of more than a dozen scientific payloads, including various radio sondes and other meteorological monitoring instruments; sensors and cameras; remote sensing equipment; laser scanner;
radiometers; and radar altimeter.
The airframe consists of a fuselage pod nacelle with a rear-mounted engine and high-mounted wing; twin
tailbooms with inverted V tail unit, constructed mainly of composites. the aircraft is launched from a cartop
mount and belly recovered (no landing gear).
The system consists of one or more air vehicles, payloads, single GCS and ground crew of three (minimum).
Aerosonde flight hours are now in excess of 5,000.