The air force was extensively used in the fighting in Chad in the 1980s, in support of Libyan ground units. It was reported that many Libyan People's Air Force bombing raids were carried out at excessively high altitudes when met with anti-aircraft fire, so the attacks were not very effective. On 17 February 1986, in retaliation for the Ouadi Doum air raid by the French air force, a single LPAF Tu-22B attacked the airport at N'Djamena. That aircraft ran into technical problems on its return journey – American early warning reconnaissance planes based in Sudan monitored distress calls sent by the pilot of the Tu-22 which probably crashed before reaching its base at Aouzou (maybe hit by twin-tubes that fired at it from N'Djamena airport). One Tu-22 bomber was shot down by a captured SA-6 missile during a Chadian attack on an abandoned Libyan base on 8 August 1987. Another Tu-22 was lost on 7 September 1987, when a battery of French MIM-23 Hawk SAMs shot down one of the two LPAF bombers that were attacking N'Djamena.