The Czech Republic air force pilot of a Saab Gripen came within an estimated 10m (33ft) of hitting a target-towing Bombardier Learjet 35 with nine cannon rounds after operating procedures broke down during a live-fire exercise, according to a report published by the Swedish Accident Investigation Board.
The incident happened on 11 October 2006, during manoeuvres involving five Czech Gripen C/Ds and five Aero Vodochody L-159 light combat aircraft, all operating from Sweden's Vidsel test range.
Also involved was a Saab Special Flight Operations (SFO) Bombardier Learjet 35 with three crew members on board, with this flown from Luleå air base and using the call sign "Target 03". Registered SE-RCA, this was towing a 4.5m-long sleeve target 600m behind its wing, with a spare target also deployed around 9m behind the aircraft.
With around 1,000 flight hours experience, including more than 270h on the Gripen, the pilot of single-seat aircraft 9235 mistakenly fired on the spare target using his 27mm Mauser BK27 internal cannon, after first checking with his wing man. "The Czech pilots discussed the target configuration in Czech on their squadron frequency. They considered that the target was close to the towing aircraft, but as they had been cleared to attack, they assumed that they had permission to fire," the report says.
© Gripen International
"During the first attack the crew of Target 03 heard a clattering sound that they had never heard before." As the hit indicator on the aircraft's spare target was switched off for the sortie, it was only after landing that the Learjet crew discovered that this had been hit nine times in its rear half, "with a good close grouping". The aircraft was not damaged during the incident, but further firing was suspended.
The report identifies factors including a "too comprehensive campaign during a limited time", and a lack of updated safety instructions for having contributed to the incident. The Czech pilots - who had little or no previous experience of live gun firing against an airborne target - also received confusing briefing instructions and were not told that the spare target would be visible during their attack runs, it adds.
Saab was meanwhile criticised for not having an established standard operating procedure for towing targets during live gun firing. "The Saab SFO Learjet 35 is not equipped in such a way that live gun firing from other aircraft at a towed target could be carried out in a manner that is consistent with flight safety," the report says. "The crew have no possibility to see the target or attacking aircraft in their rear sector, so they cannot order [an] attacking aircraft to hold its fire if the attack profile is abnormal."
The board recommends that the Swedish military review its regulations for the operation of "foreign governmental aviation on Swedish territory", and has also called on Saab to improve its ability to monitor an attacking aircraft under future such conditions. Responses are expected by 18 April 2008, it adds.