A helicopter was as little as 20 seconds away from colliding with a military jet near Aberdeen.
An official probe into the incident has blasted war game planners over the reported near miss.
The investigation was launched after a Sikorsky S92 was returning from an offshore rig to Aberdeen on November 14 cruising at a height of 2000 feet.
But at 5.47pm – about 60 miles east of the city- the helicopter pilot was alerted by air traffic control to a fast-jet descending out of 10,000 feet.
This was soon updated by control to say the Hawk aircraft was now at 2000 feet, heading directly towards them. A controller immediately issued an avoiding action turn to the north.
While in the turn, the helicopter crew observed the fast-jet’s navigation lights and their cockpit Traffic Alert and Collision Avoidance System (TCAS) issued a 20 second alert.
The helicopter pilot assessed the risk of collision as ‘medium.’
In the Aberdeen Controller’s report to the UK Airprox Board – which investigates near misses – the S92 pilot said that his TCAS showed the aircraft to have come within 300 feet vertically and two nautical miles away on the same level.
But with a closing speed of 700 knots “and within 20-48 seconds of a collision.”
The Hawk was part of an exercise that involved several other military aircraft and being controlled by “Blackdog” based at RAF Scampton in Lincolnshire.
The board said the main cause of the Airprox was that the Hawk pilot had been tasked into the Aberdeen airspace and had flown into conflict with the S92.
There were also a number of contributory factors including a lack of overall exercise safety supervision; a lack of “rigour in exercise planning and coordination” and the Hawk pilot had not been sufficiently aware of the rules relating to operating in the vicinity.
The Board commended the Aberdeen controller for his “prompt action in helping to resolve the conflict.”
The Board were also told by the military members that a safety investigation had been convened by the RAF to review the incident and had made recommendations to ensure that the mistakes were not repeated.
This incident was still the subject of a detailed investigation which has yet to be finalised.
“This incident stems from poor adherence to and/or briefing of published procedures Finally, the more ‘active’ barriers of a radar service, TCAS and see-and-avoid all functioned to some extent to prevent the situation becoming worse.” added the report.
But it added:”Notwithstanding, when it came to assessing the risk, the Board quickly agreed that there was no risk of collision because both pilots had taken avoiding action and were visual with each other well before the closest point of approach – the risk was accordingly agreed as Category C.”