The Pave Hawk helicopter involved in the Norfolk air disaster has played a prominent part in US military and humanitarian aid missions over recent years.

A derivative of the more famous Black Hawk helicopter, the Pave Hawk gets its name from the PAVE acronym standing for Precision Avionics Vectoring Equipment.

A twin turrboshaft-engined helicopter made by Sikorsky, the Pave Hawk's main function is to fly in and then recover special operations personnel.

Capable of carrying not only men but also weapons and ammunition, Pave Hawks took part in Operation Desert Storm in 1991 helping air forces in the Middle East.

Seen as a particularly versatile aircraft, the Pave Hawk helped with helping victims in Sri Lanka following the devastating Boxing Day 2004 tsunami and later in 2005 it was Pave Hawks that went to assist following the destructive Hurricane Katrina in New Orleans, USA.

The Pave Hawk has a four-man crew and can carry up to 12 troops. It is just over 17 metres long (nearly 65ft) and has a maximum speed of 224 mph, with as cruising speed of around 184 mph. The aircraft can reach heights of 14,000ft.

The aircraft has a maximum range of more than 500 miles and is equipped with all necessary and up-to-date systems to enable it to fly in all conditions. In particular it is designed with night operations in mind and is equipped with night-vision aids and automatic flight controls.

Typically, the Pave Hawk crews' training flights would replicate as close as possible real missions which would mean weapons and ammunition would be carried.