What happened
An AirBC DHC-8, registration ABL819, departed runway 26L at Vancouver on an instrument flight rules (IFR) flight bound for Prince George. Following its departure, a Central Mountain Air Beechcraft 1900D, registration GLR738, was cleared to depart the same runway. While the preceding DHC-8 was climbing at approximately 150 knots, the following Beechcraft 1900D accelerated rapidly to about 190 knots.
As the two aircraft climbed, the distance between them decreased significantly. The Beechcraft 1900D closed to within 300 feet vertically and 2 nautical miles horizontally, violating the required separation standards of 1,000 feet and 3 nautical miles. The loss of separation was further exacerbated when the DHC-8 initiated a right turn at 3,000 feet, causing the flight paths to converge. The departure controller attempted to stabilize the spacing by instructing the Beechcraft 1900D to reduce speed to 140 knots.
The investigation
Investigators examined the performance characteristics of both aircraft and the air traffic control procedures in place at the time. It was established that the Beechcraft 1900D had only recently begun operating in the Vancouver area, and controllers were not yet fully familiar with its high acceleration and climb capabilities.
Data from flight strips indicated that the tower controller had based the initial separation on en route cruise speeds rather than initial climb profiles. The investigation also found that while other controllers had observed similar "run-down" events with this aircraft type, these instances had not been formally reported to Nav Canada supervisors. Furthermore, the departure controller's radar module initially showed the Beechcraft 1900D as an uncorrelated target without a speed data tag, limiting the ability to identify the rapid closure rate.
Findings
- The departure controller had insufficient time to recognize and react to the unexpected high-overtake situation immediately after takeoff.
- A lack of awareness among air traffic control personnel regarding the initial climb performance of the Beechcraft 1900D contributed to the event.
- The pilot of the Beechcraft 1900D elected to climb at approximately 190 knots, which was significantly faster than the preceding aircraft.
- The tower controller's decision to use en route speeds to judge separation was based on incomplete data regarding the aircraft's climb profile.
- Prior similar incidents involving the Beechcraft 1900D had not been captured by the Nav Canada reporting system.
Safety action
- Vancouver ACC and Tower supervisors issued operations letters to establish new initial spacing protocols for the Beechcraft 1900D, coordinated with local airlines.
- Central Mountain Air instructed its pilots to maintain a 160-knot climb speed when following DHC-8 aircraft.
- Nav Canada implemented a new reporting system and database on January 1, 1998, to improve trend analysis and identify system deficiencies.