Description

On 13 October 2008, a DHC-8 Q400 was on heading 056 inbound to Newcastle and in receipt of Radar Advisory Service in Class 'G' Airspace. It was rerouted to avoid Spadeadam Danger Area (EGD510), which was active with an extended vertical limit as published by Notice To Airmen. Approximately 24 nm west of Newcastle, the aircraft was instructed by Newcastle RADAR to stop descent and turn left 010 as Avoiding Action because of unknown traffic passing from right to left and climbing from below the current altitude of the DHC-8. A TCAS TA then occurred followed quickly by a TCAS RA to DESCEND. This was followed and the ATC left turn instruction then acknowledged. After the DHC-8 turned left onto 010 there was another TCAS TA. The ATC avoiding action had resulted in the DHC-8 entering the Danger Area EGD510.

The unknown traffic turned out to be a Tornado GR4 fast jet operating as part of a four aircraft formation. The formation was in receipt of a radar information service from a fighter controller aboard an E3 AWACS aircraft and then was asked to ‘contact’ Spadeadam Range Control. No ATC handover took place between the AWACS and Spadeadam radar controller nor did the AWACS inform the Tornados that their flight information service (FIS) was terminated. The Spadeadam radar controller provided traffic information to the Tormado formation about the DHC-8 as soon as it came on the frequency despite the fact that the crew advised that they were receiving ‘service’ from the AWACS. Neither TCAS nor any other form of collision warning system was fitted on the military jets.

Extracts from the UKAB Review

• "Service provided by the control team on the AWACS to the Tornado formation during this Exercise would have been limited generally to tactical information about the Exercise mission;
• The absence of a formal termination of the FIS provided by the Air Defense controller would not be unusual once the jets were inbound to their target area within the confines of the Spadeadam Danger Area;
• A ‘contract’ had evidently not been established with Spadeadam for a radar service and the Spadeadam Air traffic controller (SPD) had endeavored to clarify this point at an early stage;
• It was clear that SPD astutely provided accurate and pertinent traffic information to ensure that the GR4 crew was kept closely updated over what was happening so that they might spot the airliner at the earliest opportunity;
• For their part, the GR4 crew had obtained Range entry clearance and were plainly endeavoring to steer clear of the DHC-8 whilst still trying to salvage their Exercise attack run which needed a fairly precise set-up;
• Clearly the avoiding action instruction to the DHC-8 crew that resulted in their entry into the danger area unannounced was unwise, but controller […] (representatives) were aware that Newcastle RADAR had little room to manoeuvre so close to the boundary of the Danger Area.

UKAB-determined Cause

The TCAS RA stemmed from the unintentional entry of the airliner into Spadeadam Range as a result of the avoiding action issued by Newcastle RADAR whereupon the DHC-8 crew detected the presence of the jet whilst the GR4 crew were actively avoiding the airliner. The Board therefore concluded that the Cause of this Airprox was a sighting report (TCAS) with no inherent Risk of a Collision.

Related Articles

• Separation Standards
• State Aircraft and Formation Flights - Separation Minima
• Flexible Use of Airspace
• Airspace Infringement

Further Reading

• Analysis of Airprox in UK Airspace - Jul - Dec - 2008 - Report 21 (pp. 154 - 159), UK Airprox Board