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| Title: | Loss of separation, Air Traffic Incident: HS25B, OY-RAA and B737, PH-BDO |
| Micro summary: | An en route air traffic conflict between a Boeing 737 and HS25B. |
| Event Time: | 2004-01-02 at 0935 UTC |
| File Name: | 2004-01-02-DK.pdf |
| Publishing Agency: | Accident Investigation Board (AIB) |
| Publishing Country: | Denmark |
| Report number: | HCL 04/04 |
| Pages: | 5 |
| Site of event: | 14 nm northwest of locator ML (324 KHz) near EKAH |
| First Airplane | Second Airplane | ||
| Departure: | Kangerlussuaq Airport, Greenland | Amsterdam Schiphol Airport, Amsterdam, Netherlands | |
| Destination: | Copenhagen Airport (Kastrup), Copenhagen, Denmark | Helsinki-Vantaa Airport, Helsinki, Finland | |
| Airplane Type(s): | HS25B | Boeing 737-306 | |
| Flight Phase: | Cruise | Cruise | |
| Registration(s): | OY-RAA | PH-BDO | |
| Operator(s): | Air Alsie | KLM Royal Dutch Airlines | |
| Type of flight: | Revenue | Revenue | |
| Occupants: | Unknown | ???? | |
| Fatalities: | 0 | ||
| Serious Injuries: | 0 | ||
| Minor/Non-Injured: | 0 | ||
| Other Injuries: | 0 |
| Executive Summary: | At 0933:52 hrs, a Short Time Conflict Alert (STCA) was presented to the air traffic controller on her radar display. On the radar display, the horizontal and vertical separation between aircraft A (FL 344) and aircraft B (FL 329) respectively were displayed to be 17,4 nm and 1500 feet. A TCAS Traffic Advisory (TA) advised the flight crew of aircraft B of a conflict with other traffic (aircraft A) at approximately 0934:40 hrs. On the radar display, the horizontal and vertical separation between aircraft A (FL 336) and aircraft B (FL 329) respectively were displayed to be 8,8 nm and 700 feet. At approximately 0934:55 hrs, the flight crew of aircraft B received a TCAS Resolution Advisory (RA) to take evasive action (“Climb”). The flight crew of aircraft B followed the TCAS RA without delay. At the same time, a STCA reappeared on the air traffic controller’s radar display. On the radar display, the horizontal and vertical separation between aircraft A (FL 333) and aircraft B (FL 329) respectively were displayed to be 6,0 nm and 400 feet. At 0934:57 hrs, the air traffic controller requested the flight crew of aircraft A to confirm that the aircraft was maintaining FL 340. At that time, it was the opinion of the air traffic controller that aircraft A was cleared FL 340. The flight crew of aircraft A reported that they were cleared FL 330. On the radar display at 0935:03 hrs, the horizontal and vertical separation between aircraft A (FL 332) and aircraft B (FL 330) respectively were displayed to be 4,6 nm and 200 feet. At 0935:12 hrs, the air traffic controller instructed the flight crew of aircraft A to climb to FL 340. The flight crew of aircraft B reported, “TCAS climb”, at 0935:19 hrs. At 0935:23 hrs, the air traffic controller instructed the flight crew of aircraft A to descend to FL 250. The flight crew of aircraft A did not acknowledge the instruction. Approximately at that time, the Commander of aircraft A disconnected the autopilot and initiated a climb towards FL 340 while keeping visual contact with the conflicting traffic. On the radar display, the horizontal and vertical separation between aircraft A (FL 330) and aircraft B (FL 335) respectively were displayed to be 1,9 nm and 500 feet. On the radar display at 0935:26 hrs, the horizontal and vertical separation between aircraft A (FL 330) and aircraft B (FL 335) respectively were displayed to be 0,6 nm and 500 feet. See enclosure 1. By the use of an Interactive Collision Avoidance Simulator (InCAS) programme, the Danish AAIB has calculated that the closest point of approach took place at approximately 0935:29 hrs. The calculated horizontal and vertical separation between aircraft A and aircraft B were 0,3 nm and 547 feet. Beyond this point, the separation between the two aircraft increased. |
| Learning Keywords: | Operations - Airspace - Air Proximity |
| Operations - Airspace - Air Traffic Control | |
| Operations - Airspace - TCAS |
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