What happened
On 22 March 2003, an RAF Tornado GR4A, registration ZG710, was returning to Ali Al Salem Air Base in Kuwait following a combat mission over Iraq. While the aircraft was descending at approximately 17,938 feet, it was struck and destroyed by a US Army Patriot surface-to-air missile. The missile was launched after the Patriot battery crew identified the aircraft as an Iraqi Anti-Radiation Missile. Both members of the crew, the pilot and the navigator, sustained two fatalities and were killed instantly.
The investigation
The RAF Board of Inquiry, conducted alongside US Army investigations, examined the sequence of events leading to the engagement. Investigators reviewed the aircraft's flight profile, the Patriot battery's radar data, and the functionality of the Identification Friend or Foe (IFF) systems. The inquiry also scrutinized the command and control structures, the Rules of Engagement (ROE) in effect at the time, and the communications available to the ground-based air defence units.
Findings
The investigation established that the misidentification of the aircraft as an enemy missile was the immediate cause of the accident. Several contributing factors were identified:
- Classification Criteria: The Patriot system used broad, generic criteria for identifying Anti-Radiation Missiles which the descending ZG710 met.
- IFF Malfunction: While ground checks had confirmed the encrypted Mode 4 IFF was working, the aircraft suffered an undetected power supply failure that prevented it from responding to IFF interrogations. Additionally, Mode 1 codes were not loaded in the Patriot battery.
- Rules of Engagement and Training: The existing ROE for self-defence against Anti-Radiation Missiles were not robust enough to prevent the engagement of a friendly aircraft. Furthermore, training focused on generic threats rather than specific local profiles.
- Operational Isolation: The Patriot battery was operating autonomously without full integration into the wider airspace picture due to temporary communications limitations.
- Airspace Management: Inadequate aircraft routing and misleading instructions regarding operating procedures for aircraft with inoperative IFF contributed to the risk.