26 August 2014 - Loss of seperation Groningen Airport Eelde

Notification

On 26 August 2014, two light aircraft breached the airborne separation minima during their approach to Groningen Airport Eelde (GAE). LVNL has reported this incident to the Dutch Safety Board and is conducting its own investigation.

Loss of separation

The horizontal or vertical distance between aircraft in flight is referred to as their “separation”. Separation minima have been established to maintain air traffic safety, whilst at the same time making optimum use of airspace. Air traffic control is responsible for maintaining these minimum distances between aircraft in its control zone. When two aircraft come closer to one another than the minima allow, the situation is known as a “loss of separation”.

The criteria for separation minima have been designed in such a way that they allow enough time to correct the situation before it presents a serious danger. An air traffic controller faced with a loss of separation must undertake a number of steps in a very short time.

  • Detect the loss of separation;
  • Identify an effective solution;
  • Communicate that solution to the pilot(s) concerned, in the form of instructions regarding their altitude, bearing and speed;
  • Ensure that the pilot(s) follow these instructions in order that safe separation is restored as quickly as possible;


Incident investigation

LVNL’s primary safety task is to maintain the separation of aircraft from one another, and also from vehicles and other obstacles when on the ground. Air traffic controllers internally report any incidents falling within our area of responsibility, with the aim of learning lessons from them and so reducing the chance that similar occurrences will take place again in the future. All reported incidents are investigated by LVNL, as part of our ongoing commitment to improving safety.

Summary investigation results

LVNL has conducted a summary investigation into the loss of separation between two aircraft at Groningen Airport Eelde (GAE). The results of this are now known. Below is a brief summary of the incident.

Summary

On 26 August 2014, the pilot of a Socata TB20 Trinidad (TB20) reported his wish to make a VOR/DME (VHF omnidirectional radio range/distance measuring equipment) approach to Runway 05 at GAE. At the time of this call the aircraft was flying under Visual Flight Rules (VFR) to the north of the approach path to Runway 05, on a south-westerly heading. Meanwhile, a Diamond DA42 was already making its approach to that runway.

The TB20 wished to make its VOR/DME approach under Instrument Flight Rules (IFR). One consequence of a transition to IFR is that a minimum radar separation of 3 nautical miles (nm) becomes applicable. The two aircraft were flying different courses as the TB20 switched from VFR to IFR, but their separation at that moment was just 1.8 nm (horizontal) and 500 feet (vertical). Because they were already on different courses, the loss of separation was resolved without additional corrective action being required. The incident was caused by the TB20 switching too early from VFR to IFR. Both aircraft landed safely. 

Classification: significant incident