Background
Air Nova flight 811 (ARN 811), a de Havilland DHC-8 aircraft, was on an instrument flight rules (IFR) flight from Sydney, Nova Scotia, to Halifax, Nova Scotia. Inter-Canadien flight 2240 (ICN 2240), an ATR 42, was on an IFR flight from Charlottetown, Prince Edward Island, to Halifax. ARN 811 was cleared to land on runway 33, and ICN 2240 was cleared for a visual approach to runway 24.
Sequence of Events
The airport controller initially planned for ARN 811 to land and hold short of the intersection of runway 24 in accordance with approved simultaneous intersecting runway operation (SIRO) procedures. He subsequently cancelled the hold short restriction but later decided that ARN 811 would have to hold short for ICN 2240 to land. The pilot of ARN 811 stated he was unable to comply. The controller then instructed ICN 2240 to execute a missed approach; the crew acknowledged but immediately requested to land beyond the intersection with runway 33. As ICN 2240 approached the intersection, the crew was cleared to land on runway 24. At the time ICN 2240 flew over the intersection, ARN 811 was entering the intersection of runways 33 and 24.
The controller had assumed from the radar display that ARN 811 could land before ICN 2240 and offered to cancel the hold short restriction if ARN 811 would fly directly to the threshold of runway 33. ARN 811 accepted. The controller then advised ICN 2240 that traffic was landing ahead on runway 33 and not to expect further clearance until 0.5 mile on final approach. ICN 2240 had not received a clearance to land on runway 24.
An operating irregularity occurred when the controller cleared ICN 2240 to land on runway 24 beyond the intersection with runway 33 without ensuring the approach path was clear. ARN 811 had not taxied through the intersection at the time ICN 2240 flew by with a clearance to land. The controller instructed ICN 2240, now at 0.3 miles from the threshold of runway 24, to initiate a missed approach. The pilot requested to land long instead of carrying out the missed approach, forcing the controller to re-evaluate. The controller's decision to allow ICN 2240 to land was based on his visual perception that ARN 811 had passed through the intersection, which proved erroneous. The shallow viewing angle from the tower prevented proper evaluation. The controller did not warn the pilot that the runway might not be clear.
Aftermath
NAV CANADA issued ATS Safety Bulletin Squawk 7700, Issue 2000-3, outlining dangers of not abiding by standard operating practices without establishing alternative separation. NAV CANADA also planned to amend its management and operating manuals by the end of January 2001 to direct appropriate additional defences when deviating from standard operating practices.
The Transportation Safety Board authorized the release of this report on 15 November 2000.