The English Electric Thunderbird was a British surface-to-air missile produced for the British Army. Thunderbird was primarily intended to attack higher altitude targets at ranges up to approximately 30 miles, providing wide-area air defence for the Army in the field. AA guns were still used for lower altitude threats. Thunderbird entered service in 1959 and underwent a major mid-life upgrade to Thunderbird 2 in 1966, before being slowly phased out by 1977. Ex-Army Thunderbird I's were also operated by the Royal Saudi Air Force after 1967.