On 1 December 2013, a Piaggio 180 (C-GFOX) taxiing for departure at Ottawa from the Police Apron there at night in normal ground visibility crossed an active runway ahead of a Bombardier DHC8-300 (C-GEWQ) being operated by Jazz Aviation which was taking off on a scheduled passenger flight from Ottawa to Montréal as JZA 988. Neither of the aircraft flight crews were aware of the runway incursion, and both aircraft continued their respective departures without further event.
The occurrence was investigated by the Canadian Transportation Safety Board (TSB). It was determined that although the temperature was sub-zero and light snow had been falling, the prevailing weather conditions were not relevant. The necessary factual data were obtained from ATC recordings.
It was established that the GND controller had cleared the P-180 to taxi from the Royal Canadian Mounted Police (RCMP) Apron behind the terminal to hold short of runway 07 on a route via taxiways G, B and C with a crossing of runway 14/32 explicitly included (see the annotated taxi chart below). This clearance was accompanied by an instruction to contact TWR once at the runway 07 holding point.
An annotated version of the Ottawa Taxi Chart valid at the time [Reproduced from the Official Report]
One minute after this, the same controller had, in accordance with normal practice for departing aircraft leaving the remote de-icing pad when, as in this case, runway 07 was the active runway, offered the DHC8 a departure from runway 14 in order to minimise taxi time. The DHC8 crew had accepted the offer and had been cleared by the GND controller to taxi from the de-icing pad via taxiways A and L to runway 14 and instructed to change to TWR once holding short of the runway on L. One minute after this, coordination between the GND and TWR controllers was completed for the "exchange of responsibility for runway 14" in order to allow its use by the departing DHC8 and the TWR controller took over that responsibility. He "completed a scan of the airport manoeuvring area and the Extended Computer Display System (EXCDS)" and saw that an aircraft (the P-180) was approaching Taxiway C which crossed runway 14 but "as there was no indication on the EXCDS display screen that an aircraft was taxiing for a runway" he assumed that it was en route to the de-icing pad. He then cleared the DHC8 for take-off on runway 14. By the time the aircraft had entered the runway, commenced its take-off and was accelerating through about 60 knots, the P-180 was midway across Runway 14 and the two aircraft were approximately 1,340 metres apart (see the illustration below).
The GND controller "noticed the runway incursion and estimated that (the P-180) would be clear of the runway by the time (the DHC8) reached (it)” and so no call was made for the DHC8 to reject its take-off. The DHC8 flight crew did not see the P-180, a small and relatively inconspicuous aircraft, cross the runway in front of them but they were "able to see past the intersection of runway 14 and taxiway C and had noted an aircraft landing on runway 07 just before they were cleared for take-off". Following the occurrence the GND controller was routinely suspended and the TWR controller was left alone to provide all ATC service for 40 minutes until a second controller arrived to assist.
An annotated version of the recorded ASDE display as the P-180 crossed runway 14 [Reproduced from the Official Report]
It was noted that:
- ATIS stated that Runway 07 was being used for arrivals and departures. The ATIS did not mention that Runway 14 was also being used for departures
- The P-180 pilot would have been on the GND frequency when it would have been apparent from transmissions that aircraft were using runway 14 for departure.
- When the P-180 was given its taxi instructions, the DHC8 was on the de-icing pad and its crew were not monitoring the GND frequency so they were not aware that the P-180 was taxiing to Runway 07 without a restriction to hold short of Runway 14.
- Staffing guidelines for the Ottawa Control Tower suggested that a minimum of 4 controllers should be on duty during ab evening shift like the one during which the event occurred but only two were on duty, one working the GND position including clearance delivery and the other working the TWR position. It was found that staff shortages at the Ottawa TWR were "common".
- Use of the EXCDS functionality for departing aircraft, in particular by GND controllers, was found to vary and its updating was not subject to prescriptive procedure but left to "the discretion of individual controllers". The fact that the P-180 was taxiing as cleared was not evident from the TWR Controller's EXCDS display.
- In the exchange of responsibility for runway 14, the GND Controller did not mention that the P-180 was en route to the 07 hold and had been cleared to cross runway 14; there was "no indication that the GND controller recollected or recognised that (the P-180) was about to cross Runway 14". At the time he had "responsibility for 8 aircraft and 3 sets of vehicles", of which the only aircraft taxiing was the P-180.
- The Unit Operations Manual contained a list of five criteria, the presence of any one of which was expected, when staffing permitted, to result in the opening of the Clearance Deliver Position. At the time of the occurrence, four of the five listed criteria applied.
The formally stated Findings as to Causes and Contributing Factors were as follows:
- The Ground controller issued instructions to C-GFOX to taxi unrestricted from the Royal Canadian Mounted Police Apron to Runway 07, despite the frequent use of Runway 14 for departing aircraft.
- The Ottawa Tower Extended Computer Display System (EXCDS) Manual requires that the ground controller forward the flight data entry (FDE) of an aircraft taxiing for departure to the 'Taxied' panel so that an FDE will be generated in the applicable 'Departure' panel of the (Tower) controller’s display screen. However, the Ottawa Tower Unit Operations Manual and unit directives do not indicate when to initiate this transfer, leaving the decision to the discretion of individual controllers.
- Following the issuance of taxi instructions to C-GFOX, the Ground controller did not initially forward the C-GFOX flight data entry from the Cleared panel to the Taxied panel and, therefore, the (Tower) controller’s Extended Computer Display System display screen did not indicate that C-GFOX was taxiing for Runway 07.
- The Ground controller did not verify the position of C-GFOX relative to Runway 14 prior to transferring the responsibility for Runway 14 to the (Tower) controller.
- The (Tower) controller cleared JZA988 for take-off on Runway 14, and C-GFOX subsequently entered Runway 14 as JZA988 was departing, leading to the runway incursion and risk of collision.
The formally stated Findings as to Risk were as follows:
- If there is insufficient staff available to deal with staffing shortfalls, there is an increased risk of error due to workload and fatigue.
- If the air navigation service provider does not provide clear direction as to when flight data entries have to be forwarded within the Extended Computer Display System, there is a risk that control instructions will be issued without a complete understanding of the operational environment.
Safety Action taken by ANSP NAV CANADA as a result of the occurrence was noted to have included a review of its procedures for operating when short-staffed and the issue of a "Tower Operations Directive" at Ottawa which was subject to a mandatory verbal briefing. This introduced more effective use of the EXCDS when runway crossings are included in clearances.
The Final Report of the Investigation was authorised for release on 10 June 2015 and it was officially released on 16 July 2015. No Safety Recommendations were made.