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ASN Wikibase Occurrence # 176663
Last updated: 24 May 2017
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Date:05-JUN-2015
Time:14:57
Type:Silhouette image of generic B736 model; specific model in this crash may look slightly different
Boeing 737-6CT
Owner/operator:WestJet
Registration: C-GWCT
C/n / msn: 35112/2016
Fatalities:Fatalities: 0 / Occupants: 112
Other fatalities:0
Airplane damage: None
Category:Serious incident
Location:Montreal-Pierre Elliott Trudeau International Airport, QC (YUL/CYUL) -   Canada
Phase: Landing
Nature:Domestic Scheduled Passenger
Departure airport:Toronto-Pearson International Airport, ON (YYZ/CYYZ)
Destination airport:Montreal-Pierre Elliott Trudeau International Airport, QC (YUL/CYUL)
Investigating agency: Transportation Safety Board (TSB) - Canada
Narrative:
WestJet flight 588 (WJA588) departed Toronto/Lester B. Pearson International Airport (CYYZ), Ontario, on a scheduled flight to Montréal/Pierre Elliott Trudeau International Airport (CYUL), Quebec. The captain was the pilot flying (PF) and the first officer was the pilot not flying (PNF). While en route, the PNF uploaded the applicable standard arrival procedure and the runway 24L approach to the flight management system before completing the approach briefing. The calculated landing distance obtained from the aircraft communications addressing and reporting system (ACARS) was 7784 feet with flaps set to 30° and the autobrake system set to 1. Because the gate where the aircraft was to park was close to the end of the 9600-foot-long runway, the PF planned to exit at the far end of runway 24L, and the crew set up for a landing with flaps set to 30° and the autobrake system set to 1.
During descent, the crew obtained automatic terminal information service (ATIS) information Lima, issued at 14:18, which was as follows: weather at 1412, wind 240° magnetic (M) at 8 knots, visibility 15 statute miles (sm) in light rain showers, broken towering cumulus clouds at 4500 feet above ground level (AGL), another broken layer at 7500 feet AGL and overcast at 24 000 feet AGL, temperature 23°C, dew point 16°C, altimeter 29.91 inches of mercury, instrument flight rules approach instrument landing system (ILS) runway 24L and ILS runway 24R, visual flight rules runway 24L. Based on this information, the PF planned to carry out a visual approach to runway 24L with the ILS approach as back-up.
While being vectored for the approach, the crew observed on the aircraft weather radar that there was moderate to heavy rain activity north-northwest of the field. Once on a heading of 330°M, on the left base leg for runway 24L, the crew observed that the weather radar showed heavy rain on the approach path, but no turbulence or hail. At 14:53, when it was approximately 8.8 nautical miles (nm) from the runway, the aircraft was configured for landing: flaps extended to 30°, landing gear extended, and speedbrakes armed.
At 14:55, WJA588 called the tower controller to advise that the aircraft was established on the ILS for runway 24L. Shortly thereafter, WJA588 received clearance to land and was told to expect to exit at the end of the runway. The wind reported to the crew was 350°M at 17 knots with gusts to 22 knots. At that time, the aircraft was flying through heavy rain showers. The wipers were selected on.
The ILS approach was coupled with the autopilot and autothrust (A/T) engaged. The A/T was in SPEED MODE, and the initial selected speed on the mode control panel (MCP) was 130 knots. However, it was increased to a final value of 140 knots while the aircraft was descending through 740 feet AGL. The recorded landing reference speed (Vref) was 125 knots; therefore, the final selected speed was Vref + 15.
The autopilot was disengaged as the aircraft descended through approximately 280 feet AGL. The aircraft began to deviate above the glideslope and crossed the threshold at 52 feet AGL at a speed of 145 knots (Vref + 20) at 14:57:48. Ten seconds later, the aircraft touched down on its right main landing gear about 2550 feet beyond the threshold at a speed of 133 knots. The speedbrakes automatically deployed. The aircraft briefly bounced after final touchdown, and, at 14:58:01, the autobrakes activated and both thrust reverser levers were brought to idle detent.
At 14:58:08, at a speed of 103 knots, with 4940 feet of runway remaining, the PF manually stowed the speedbrakes, which disarmed the autobrakes. Nine seconds later, at 14:58:17, the PF applied manual braking; the speed was 92 knots, with 3320 feet of runway remaining. Full brake pressure was obtained while the aircraft was at a speed of 85 knots, with 2270 feet of runway remaining. At 83 knots, the PF applied maximum reverse thrust. At that point, the PF had steered the aircraft to the right of the runway centreline to avoid the runway end lights and the approach lighting system for the opposite runway. Full reverse thrust (83% N1) was obtained 10 seconds later. At that point, the aircraft speed was 55 knots, with 550 feet of runway remaining. At 14:58:43, at a ground speed of approximately 39 knots, the aircraft departed the paved surface of the runway and travelled approximately 200 feet into the grass before coming to a stop 200 feet to the right of the runway centreline at 14:58:48.
No one was injured, and all passengers and crew deplaned by a mobile staircase placed at the front right door.


Findings as to causes and contributing factors
1. The knowledge that precipitation was intensifying at the airport did not prompt the crew to expect that the runway could be contaminated rather than just wet, and, as a result, they continued to expect good braking performance on a wet runway.
2. The crew calculated an inaccurate target approach speed and crossed the threshold 15 knots faster than recommended. Combined with a tailwind and a slightly high flare, this resulted in the aircraft touching down beyond the normal touchdown zone, thus reducing the amount of runway available for stopping.
3. The captain delayed the selection of maximum thrust by approximately 25 seconds after touchdown. Consequently, the distance required to stop the aircraft increased.
4. The captain stowed the aircraft's speedbrakes above the speed of 80 knots specified in WestJet's standard operating procedures, and they were not redeployed during the landing roll. This reduced the normal load on the gear and the aerodynamic drag. Consequently, the deceleration rate decreased, which increased the stopping distance.
5. The instruction to exit at the end of the runway contributed to the minimal use of deceleration devices early in the landing roll, as the crew were attempting to expedite their exit at the end of Runway 24L.
6. It is likely that viscous hydroplaning occurred when the aircraft was approaching the end of the runway, as shown by the lack of deceleration once maximum braking was applied. Combined with the downslope, this reduced the possibility of stopping on the runway.

Findings as to risk
1. If operators do not consider making more conservative time-of-arrival assessments when active heavy precipitation exists, then there is a risk of runway overrun.
2. If there is no specific guidance on how to assess and report runway surface conditions during non-winter months, then there is a risk that crews will be unable to properly assess landing conditions.
3. If procedures and guidance do not prompt flight crews to anticipate less-than-good braking conditions on wet runways, then there is a risk that landing distance and aircraft management will be inadequate to provide for safe stopping performance.
4. If pilots do not identify a point at which a go-around should be initiated if the aircraft is not on the ground, then there is a risk that the landing will result in a runway overrun.
5. If crews are not provided with clear clues to indicate how far from the end of a runway they are, then there is a risk that deceleration devices will not be used in a timely manner to prevent a runway overrun.
6. If pilots limit the use of deceleration devices to comply with a real or perceived requirement to expedite exiting at the end of the runway, then there is a risk that the landing will result in a runway overrun.
7. If Code 4 runways do not have a 300 m runway end safety area or a means of stopping aircraft that provides an equivalent level of safety, then there is a risk of injuries to occupants in the event of a runway overrun.

Other findings
1. The crew's initial plan for the arrival, using autobrake setting 1 and thrust reverser to provide minimal deceleration, was consistent with existing guidance that a wet runway should provide good braking action.
2. The pilot flying intentionally disarmed the autobrake by retracting the spoilers at 103 knots and no manual brake application occurred until 16 seconds after touchdown. Therefore, it is reasonable to believe that the pilot flying judged that there was sufficient runway remaining when the spoilers were retracted, based on the observed runway condition.

Sources:

http://www.bst-tsb.gc.ca/eng/rapports-reports/aviation/2015/a15q0075/a15q0075.asp

http://flightaware.com/live/flight/WJA588/history/20150605/1800Z/CYYZ/CYUL
http://www.flightradar24.com/data/airplanes/c-gwct/#6723854

Accident investigation:
cover
investigating agency: Transportation Safety Board (TSB) - Canada
status: Final
number: A15Q0075
released:16 May 2017
duration of investigation: 1 year and 12 months
download report: A15Q0075

Images:



Revision history:

Date/timeContributorUpdates
05-Jun-2015 19:23 harro Added
05-Jun-2015 19:31 harro Updated [Time, Aircraft type, Registration, Phase, Nature, Departure airport, Destination airport, Embed code, Narrative]
05-Jun-2015 19:34 harro Updated [Cn, Source, Embed code, Narrative]
05-Jun-2015 19:42 harro Updated [Narrative]
27-May-2016 19:13 AF5541 Updated [Total fatalities]
16-May-2017 19:15 harro Updated [Time, Total fatalities, Source, Damage, Narrative]
16-May-2017 19:18 harro Updated [Photo, ]
16-May-2017 19:18 harro Updated [Photo, ]
16-May-2017 19:31 harro Updated [Source, Narrative]

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