The crash of a Ukrainian air force Sukhoi Su-27 fighter into the crowd at an air show at Sknyliv airbase near Lviv on 27 July could force a rethink of display safety by regulators including the UK's Civil Aviation Authority. The accident killed 83 on the ground, while 116 were injured.

The Ukrainian organisers have been criticised for permitting the display to take place over the crowd. Civilian air show regulations in the European Joint Aviation Authorities countries are largely based on the CAA's CAP403 regulations and prohibit overflying of the crowd, except under "exceptional conditions". Military regulations, like those enforced at the Farnborough and Paris shows, do not differ significantly from CAP403.

Permitted proximity to the crowd line is dependent on an aircraft's speed and manoeuvres. The closest is 50m (165ft) for non-aerobatic flying under 100kt (185km/h). For an aircraft flying over 200kt and performing aerobatics, the separation required is 250m.

The CAA issued a consultation document late last month for the ninth edition of CAP403. Potential revisions include much greater provision of emergency services and tighter regulations on formation flying. This revision should be in place by the first quarter of next year.

During the Ukrainian display the aircraft appeared to have insufficient height to complete a manoeuvre and its speed was too low, with the fighter apparently stalling and the left wing dropping and hitting the ground. Both pilots ejected and are being questioned.

Smoke was seen coming from the aircraft's engines before the crash, but this is not unusual for the Su-27. Although the air force initially suggested an engine problem as the cause of the accident, Sukhoi is eager to clear the aircraft of any technical malfunction.

Source: Flight International