The Tornado GR4 is a two-seat, all-weather, day/night attack and reconnaissance aircraft. It has been in service with the RAF for more than 30 years, but a combination of major upgrade programmes and numerous continual enhancements has kept the aircraft amongst the forefront of all attack aircraft. In 1984, the UK Ministry of Defence began studies for a GR1 Mid-Life Update (MLU). The update to GR4 standard, approved in 1994, would improve capability in the medium-altitude role based on lessons learned from the GR1's performance in the 1991 Gulf War. British Aerospace (later BAE Systems) upgraded 142 Tornado GR1s to GR4 standard, beginning in 1996 and finished in 2003. 59 RAF aircraft are receiving the CUSP avionics package which integrates the Paveway IV bomb and installs a new secure communications module from Cassidian in Phase A, followed by the Tactical Information Exchange (TIE) datalink from General DynamicsWhen the Tornado GR1s were upgraded to become GR4s, GR1A aircraft were upgraded to GR4A standard. The switch from low-level operations to medium/high-level operations means that the internal TIRRS is no longer in use.
