Canada A320 at Toronto on Feb 25th 2017, runway excursion on landing

Last Update: April 25, 2018 / 14:56:56 GMT/Zulu time

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Photo of Air Canada C-FDRP, Airbus A320 — Air Canada C-FDRP, Airbus A320 (Photo credit: abdallahh / Flickr / License: CC by)

Incident Facts

Date of incident
Feb 25, 2017

Classification
Incident

Cause
Runway excursion

Airline
Air Canada

Flight number
AC-623

Departure
Halifax, Canada

Destination
Toronto, Canada

Aircraft Registration
C-FDRP

Aircraft Type
Airbus A320

ICAO Type Designator
A320

Airport
Lester B. Pearson International Airport, Toronto

Airport ICAO Code
CYYZ

An Air Canada Airbus A320-200, registration C-FDRP performing flight AC-623 (dep FEb 24th) from Halifax,NS to Toronto,ON (Canada) with 112 passengers and 6 crew, landed on Toronto's runway 15R at 00:02L (05:02Z) in low visibility but veered right off the runway and came to a stop disabled on the runway. The crew announced "stopping on the runway" prompting tower to instruct the next two arrivals to go around. The crew subsequently advised they had veered right off the runway and needed the trucks (emergency services). Emergency services and busses responded, the passengers disembarked onto the runway and were bussed to the terminal.

The runway is still closed about 13.5 hours after the runway excursion.

The Canadian TSB have dispatched a team of investigators on site.

The airline reported the aircraft temporarily left the paved surface of the runway before returning onto the runway.

The airport reported the aircraft has been moved off the runway by now, repairs and runway inspection are underway, the TSB investigation is ongoing.

On Feb 26th 2017 the TSB reported the aircraft performed an ILS approach to runway 15R. During the landing sequence the aircraft travelled through the grass on the western (right hand) side of the runway and came to a stop on the runway center line. There were no injuries, the aircraft received minor damage, 5 runway edge lights were damaged, too.

On Apr 25th 2018 the TSB released their final report concluding the probable causes of the serious incident were:

Findings as to causes and contributing factors

- For undetermined reasons, during the transition to flare, while the aircraft was on the runway centreline, the pilot flying made a right roll command input, which resulted in the aircraft entering a shallow right bank and beginning to drift to the right.

- The flight crew had limited visual cues available to accurately judge the aircraft's lateral position given the weather conditions, reduced windshield wiper capability and lack of runway centreline lighting.

- Once over the runway surface, the flight crew had to judge the aircraft’s lateral position based solely on their assessment of the degree of asymmetry between the runway edge lights. As a result, the onset of drift was not initially noticed.

- The severity of the drift was not recognized until the aircraft was less than 10 feet above ground level and rapidly approaching the runway edge, leaving limited time to correct the aircraft’s trajectory before the aircraft contacted the surface.

- Once the flight crew recognized that the aircraft would exit the paved runway surface, the pilot flying continued the landing roll as opposed to executing a go-around following contact with unknown terrain and objects.

Findings as to risk

- There is an increased risk that visual cues may be reduced while flying in precipitation if fitted rain repellent systems are not used.

- If the distance between runway edge lights is greater than 50 m and runways are not equipped with centreline lighting, there is a risk that visual cues will be insufficient for flight crews to detect lateral drift soon enough to prevent an excursion, while operating aircraft at night during periods of reduced visibility.

The TSB analysed with respect to weather:

Although there was low-level wind shear in the area through which the aircraft transited during final descent, by the time the aircraft was below 500 feet above ground level (AGL) on approach, the wind had decreased to less than 5 knots, and the aircraft’s trajectory and speed were stable.

From this point until the pilot flying’s (PF’s) right roll control input, the angle between the aircraft’s longitudinal axis and the track over the ground was nearly 0, indicating there was no into-wind crab angle being applied and no significant lateral wind component.

Because the aircraft’s lateral movement was consistent with recorded control inputs, it was determined that a variation in wind speed or direction was not the cause of the aircraft’s lateral deviation.

With respect to visibility the TSB analysed:

The various weather reports received by the crew in the hour preceding the approach described the visibility as between 3/8 statute miles (sm) and ½ sm in fog. The runway visual ranges (RVRs) for Runway 15R were reported to be as low as 3000 feet, but occasionally variable up to 5500 feet.

While issuing the flight’s landing clearance approximately 2 minutes before touchdown, air traffic control (ATC) informed the flight crew that the RVR was 3000 feet.

The occurrence flight crew and a few other flight crews that were operating on the ground at Toronto/Lester B. Pearson International Airport (CYYZ) at the time of the occurrence perceived the actual visibility to be not as high as the visibility recorded and reported by ATC. However, the reason for this disparity could not be determined.

If the visibility was in fact less than reported, it would have reduced the visual cues available to the flight crew to accurately assess their position.

The TSB analysed the runway lighting:

Although Runway 15R complies with the regulatory standards for runway lighting, it does not follow the recommendations outlined in the edition of Transport Canada’s Aerodrome Standards and Recommended Practices (TP 312) that was in effect at the time of certification, or the recommendations in the current edition of the International Civil Aviation Organization’s Annex 14 to the Convention on International Civil Aviation.

These recommendations call for centreline lighting when the runway edge lights are spaced more than 50 m apart. On Runway 15R, the spacing is 63 m. On runways without centreline lighting, as the distance between runway edge lights increases, it becomes more difficult to judge lateral movement solely by assessing the degree of asymmetry between the runway edge lights—especially when the aircraft is close to the ground and the flight crew’s attention is focused directly ahead of them.

The TSB has investigated a number of lateral runway excursions that occurred on runways without centreline lighting. If the distance between runway edge lights is greater than 50 m and runways are not equipped with centreline lighting, there is a risk that visual cues will be insufficient for flight crews to detect lateral drift soon enough to prevent an excursion, while operating aircraft at night during periods of reduced visibility.

The TSB concluded the analysis with recognition of the drift and pending runway excursion:

The flight crew had limited visual cues available to accurately judge the aircraft’s lateral position given the weather conditions, reduced windshield wiper capability, and lack of runway centreline lighting.

Once over the runway surface, the flight crew had to judge the aircraft’s lateral position based solely on their assessment of the degree of asymmetry between the runway edge lights. As a result, the onset of drift was not initially noticed.

The pilot monitoring (PM) ultimately noticed the drift after it became significant and alerted the PF. However, the severity of the drift was not recognized until the aircraft was less than 10 feet AGL and rapidly approaching the runway edge, leaving limited time to correct the aircraft’s trajectory before the aircraft contacted the surface.

Reaction

Despite the drift, the PF initially felt that it was still possible to land on the runway surface and made control inputs to return the wings to level; however, this correction was insufficient to counteract the aircraft’s lateral momentum.

Two seconds after the inputs were made, the main wheels made initial contact with the ground, and the PF recognized the severity of the drift and the likely runway excursion. At this point, there remained only 2 options: to execute a go-around, or to continue the landing sequence and attempt to minimize the extent of the excursion.

The aircraft was in a low-energy state, as the thrust had already been reduced to idle. A go-around from this point, although possible, would have included an uncertain period of time travelling on the ground on a surface outside of the runway dimensions.

A go-around executed from a low level in response to significant drift may lead to contact with obstacles outside of the runway area, potentially causing damage to the aircraft. If the aircraft is damaged and then becomes airborne, executing the go-around may end up being more dangerous than continuing the landing from the same position.

In this occurrence, once the flight crew recognized that the aircraft would exit the paved runway surface, the PF continued the landing roll as opposed to executing a go-around following contact with unknown terrain and objects.

Related NOTAM:
02/037 (170118) - CYYZ RWY 15R/33L CLSD, AVBL AS TWY NORTH OF TWY H. 25 FEB 05:40 2017 UNTIL 25 FEB 17:00 2017. CREATED: 25 FEB 05:45 2017

Metars:
CYYZ 250718Z 13009KT 2 1/2SM RA BR OVC002 03/02 A2953 RMK NS8 SLP005
CYYZ 250700Z 16009KT 130V200 3SM -RA BR OVC003 03/03 A2953 RMK NS8 SLP006
CYYZ 250600Z 14002KT 3SM -RA BR OVC003 03/03 A2950 RMK NS8 SLP997
CYYZ 250542Z 08010KT 2SM -RA BR OVC003 03/03 A2949 RMK NS8 PRESFR SLP992
CYYZ 250528Z 06009KT 3/4SM R15L/P6000FT/U R06L/P6000FT/D R05/6000FT/D R15R/P6000FT/U -SHRA BR VV002 03/03 A2951 RMK FG8 PRESFR SLP998
CYYZ 250515Z VRB07KT 3/4SM R15L/2600VP6000FT/U R24R/3000V6000FT/U R15R/3000VP6000FT/U -TSRA BR VV002 03/03 A2956 RMK FG8 OCNL LTGIC SLP016
CYYZ 250500Z VRB02KT 3/8SM R15L/2800FT/N R24R/3000FT/D R15R/3500FT/U -TSRA FG VV001 03/03 A2956 RMK FG8 OCNL LTGIC PRESFR SLP018
CYYZ 250450Z CCA 22005KT 170V230 3/8SM R15L/3000FT/N R24R/3500V5000FT/U R15R/3500FT/U -TSRA FG VV001 03/03 A2959 RMK FG8 OCNL LTGIC PRESRR SLP028
CYYZ 250429Z VRB03KT 3/8SM R15L/3000FT/N R24R/3000FT/N R15R/3000FT/D FG VV001 03/03 A2956 RMK FG8 PRESFR SLP017
CYYZ 250400Z 12006KT 1/2SM R15L/4500VP6000FT/N R24R/4000V5500FT/D R15R/3000V5500FT/D FG VV002 03/03 A2956 RMK FG8 SLP017
CYYZ 250313Z 11007KT 1/4SM R15L/2800VP6000FT/D R24R/2600FT/N R15R/3500V4500FT/NFG VV001 03/03 A2956 RMK FG8 SLP017
CYYZ 250300Z 11007KT 1/2SM R15L/3500VP6000FT/U R24R/3500FT/D R15R/5000FT/D FG VV001 03/03 A2957 RMK FG8 SLP020
CYYZ 250232Z 09007KT 070V140 1/2SM FG VV001 04/03 A2958 RMK FG8 SLP022
CYYZ 250224Z 12008KT 3/4SM BR VV002 04/03 A2958 RMK FG8 SLP023
CYYZ 250200Z 12006KT 2SM BR OVC002 04/03 A2959 RMK ST8 PRESFR SLP026