History of the Flight
Air Canada Jazz flight JZA7779, operated with a DHC-8-100 (registration C-GTBP, serial number 066), departed Toronto/Lester B. Pearson International Airport, Ontario, under instrument flight rules for a regularly scheduled service to North Bay, Ontario. The flight crew planned a stabilized constant descent angle (SCDA) non-precision approach to Runway 08 at North Bay Jack Garland Airport.
Before departure, the crew reviewed weather and notices to airmen (NOTAM). A NOTAM indicated the glideslope for the instrument landing system (ILS) Runway 08 was unserviceable. The latest weather report showed reduced visibility due to light drizzle and mist with a low ceiling. The runway visual range (RVR) was 6000 feet. The forecast suggested improving conditions at the planned arrival time.
The runway surface condition (RSC) report for Runway 08/26 indicated the centre 120 feet was 60% bare and wet, 40% compact snow, with the remainder 100% compact snow. The Canadian Runway Friction Index (CRFI) was 0.33.
The flight departed Toronto at 2306. The first officer was the pilot flying, the captain was the pilot not flying. During the descent, the crew briefed for an SCDA localizer approach for Runway 08 using pilot monitored approach (PMA) procedures, targeting 120 knots indicated airspeed, crossing the final approach fix (FAF) at 2500 feet above sea level, descending at 700 feet per minute to the minimum descent altitude (MDA) of 1480 feet.
The autopilot was engaged throughout the approach. The aircraft turned onto the final approach track, levelling at 2500 feet 0.2 nautical miles before the FAF. It crossed the FAF at approximately 170 knots indicated (200 knots ground speed). The aircraft began decelerating after the FAF, slowed to flap and landing gear extension speeds, and initiated descent 1 nautical mile past the FAF at about 700 feet per minute, remaining above the desired path. At 3.3 nautical miles past the FAF, it reached the target airspeed of 120 knots (140 knots ground speed) in landing configuration. The aircraft crossed the missed approach point at an approximate altitude of 1700 feet, 220 feet above the MDA. The crew was unaware they were above the flight path.
Continuing descent, at or near the MDA, a limited number of runway edge lights became visible. Using PMA, the captain assumed control, disconnected the autopilot, and began landing. The aircraft touched down with an airspeed of 109 knots (Vref + 5 knots), with 1200 to 1050 feet of runway remaining. The runway end lights were not sighted; shortly after touchdown, the approach lights for Runway 26 appeared.
The aircraft departed the runway end at approximately 58 knots indicated airspeed and came to rest approximately 260 feet past the threshold of Runway 26 in two to three feet of snow. No apparent damage was noted, so the crew kept engines running for heat and electrical power.
Stabilized Constant Descent Angle Non-Precision Approach
Transport Canada issued Commercial and Business Aviation Advisory Circular (CBAAC) 0238 on 08 September 2006 regarding SCDA approaches. The aim is to minimize vertical manoeuvring during non-precision approaches, achieving a vertical path similar to a normal glide path. The aircraft descends stabilized from the FAF to the MDA, configured for landing, with stable airspeed, power, and attitude. When flown correctly, the missed approach point occurs before the published MAP.
The SCDA technique reduces pilot workload by decreasing the number of descent initiation points and level-off altitudes. It improves terrain and obstacle clearance for most of the approach.
Instrument Approach Design Criteria and Depiction
According to ICAO Annex 4, criteria for instrument approach procedures are in PANS-OPS (document 8168). Annex 4 requires a table showing altitudes/heights per distance when DME is used in the final approach segment. A rate of descent table and final approach descent gradient are recommended. PANS-OPS state that descent profile advisory information, such as distance/altitude tables, should be provided for continuous descent final approaches. In Canada, TP 308 is the standard for instrument procedure design, but it does not specify creation of DME/altitude checkpoints for non-precision approaches, and NAV CANADA does not publish them in the Canada Air Pilot. Consequently, Jeppesen charts for Canada omit altitude/distance checkpoints in their profile view.
Air Canada Jazz Procedures
The Air Canada Jazz aircraft operating manual (AOM) outlines SCDA approaches with limitations and guidance. For non-precision approaches, the aircraft is to be configured for landing with landing gear down, flap 15°, airspeed 120 knots, and landing check completed one to two miles before the FAF. The aircraft must be level crossing the FAF. Descent rate is determined from the profile view of the approach plate. For a ground speed of 120 knots, the rate is 646 feet per minute, rounded to 700 fpm.
The aircraft was equipped with a Universal Avionics System Corporation (UASC) FMS with a vertical navigation (VNAV) feature that could be coupled to the flight guidance control panel. However, the localizer approach for Runway 08 was not a stand-alone GNSS, and the AOM and aircraft flight manual prohibited using FMS navigation for localizer-based approaches, so the pseudo glideslope from VNAV was unavailable. Both flight crew members routinely flew approaches with vertical guidance.
The AOM outlines PMA procedures, where the pilot not flying monitors the approach and the pilot flying handles landing once the runway is in sight. The crew did not use distance information from DME or FMS during the final descent.