The Australian Transport Safety Bureau has released a preliminary report into its ongoing investigation of a mid-air collision involving two jet trainer aircraft over Port Phillip Bay, south of Melbourne, in November. 

On 19 November 2023, a pair of SIAI Marchetti S-211 aircraft were being used for an aerobatic formation filming flight when they came into contact, with one of the two aircraft subsequently departing controlled flight before colliding with the water below, fatally injuring both occupants. 

“Today’s preliminary report provides factual information from the early evidence gathering phase of our ‘no blame’ transport safety investigation,” ATSB Chief Commissioner Angus Mitchell explained. 

“It does not include any analysis or findings, which will be detailed in the final report we will release at the conclusion of the investigation.” 

The preliminary report notes the S-211s, both ex-military aircraft used for pilot training, had left Essendon in what was designated ‘Viper formation’. 

Viper 1, the lead aircraft, was carrying a pilot and safety pilot, while Viper 2 was carrying a pilot and camera operator. 

“As discussed in the pre-flight briefing, the pilots’ first planned manoeuvre involved Viper 1 flying inverted, straight and level, so Viper 2 could move alongside it, upright, to then manoeuvre as required to maintain separation and conduct filming,” Mr Mitchell said. 

During the second attempt at this manoeuvre, when Viper 1 rolled inverted, the pilot of Viper 2 passed below and to the left of Viper 1. 

“The safety pilot in Viper 1 observed Viper 2 pass beneath and alerted the pilot of Viper 1 to the manoeuvre,” Mr Mitchell said. 

“Afterwards, the pilot of Viper 2 advised the pilot of Viper 1 that it provided a good filming opportunity, and asked to repeat it.” 

After the pilots discussed this manoeuvre, they decided to attempt it again. 

“On this next attempt, after Viper 2 passed beneath, it began to pitch up and bank away from Viper 1, and the right wings of each aircraft collided,” Mr Mitchell said.  

Video footage taken from fixed cameras on board Viper 1 showed that as the aircraft collided, the outer right wing structure of Viper 2 immediately failed, with deformation to the forward wing spar and separation of the lower wing skin. The right aileron control system also appeared to be significantly damaged. 

Witnesses observed Viper 2 impact the water in a near-vertical, nose down attitude at high speed. The aircraft was extensively damaged and came to rest on the floor of Port Phillip Bay at a depth of 24 metres. 

Fortunately, Viper 1 was able to return to Essendon, having sustained only minor damage. 

“Several impact marks and paint transfers from Viper 2 were present on the upper surface of Viper 1’s right wing, and its landing light cover was shattered,” Mr Mitchell detailed. 

As the ATSB’s investigation progresses, it will include consideration of formation flying procedures and practices, further analysis of recorded video and audio, a review of the category of operation, and a range of other investigative activities. 

“A final report will be released at the conclusion of the investigation, but if we identify a critical safety issue during the course of the investigation, we will immediately notify relevant parties so appropriate and timely safety action can be taken.” 

Read the preliminary report: Mid-air collision involving SIAI-Marchetti S211s, VH-DZJ and VH-DQJ, 25 km west of Tyabb Airport, Victoria, on 19 November 2023 

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