Kelowna B722 at St. John's on Jul 16th 2011, overran runway

Last Update: February 14, 2013 / 21:05:37 GMT/Zulu time

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Incident Facts

Date of incident
Jul 16, 2011

Classification
Incident

Aircraft Type
Boeing 727-200

ICAO Type Designator
B722

The Canadian TSB released their final report concluding the probable causes were:

Findings as to causes and contributing factors

1.The aircraft touched down about 1850 feet from the threshold, and at a higher than required airspeed, which reduced the available runway length to stop the aircraft.

2.Excessive tread wear and the wet runway caused the aircraft to hydroplane, which led to a loss of directional control and braking ability, resulting in the aircraft overrunning the runway.

3.The brakes were not released when the skid occurred, which reduced the effectiveness of the anti-skid system.

Findings as to risk

1.Utilizing tires that are more than 80% worn reduces the wet runway traction thereby increasing the risk of hydroplaning and possible runway overruns.

2.The practice of not testing the runway surface microtexture increases the risk of wet runway hydroplaning due to an incomplete assessment of the runwayÂ’s overall friction characteristics

3.The lack of adequate runway end safety areas (RESA) or other engineered systems or structures designed to stop aircraft that overrun increases the risk of aircraft damage and passenger injuries.

4.The use of non-grooved runways increases the risk of wet runway overrun due to a reduction in braking characteristics.

5.If all employees do not fully understand their reporting obligations and have not adopted a safety reporting culture as part of everyday operations, SMS will be less effective in managing risks.

6.When an operatorÂ’s SMS is not fully effective, there is an increased risk that hazards will not be identified and mitigated.

7.The lack of clearly defined runway surface condition (RSC) reporting standards related to water on runways increases the risk of hydroplaning.

8.If cockpit voice recorders (CVR) and flight data recorders (FDR) are not checked in accordance with regulations, there is risk that the recorded data will not be useable and potentially valuable information may not be recorded.

Other finding

1.Main wheel assembly part number 10-61287-14 is not identified on the list of approved-main landing gear wheel assemblies for aircraft operating up to 195 500 pounds maximum taxi weight.

The Canadian TSB reported that the crew, the captain (ATPL, 8,688 hours total, 6,171 hours on type) was pilot flying and the first officer (ATPL, 2,750 hours total, 2,500 hours on type) pilot monitoring, performed an ILS approach to runway 11, the computed Vref was 154 knots (140 knots for flaps 30 plus 7 knots for steady wind compensation plus 7 knots for gust compensation), there was light rain and the runway was wet. The crew became visual with the runway about 1 minute prior to touchdown, the main wheels contacted the runway about 1850 feet past the runway threshold at a speed of between 157 and 162 knots. The spoilers were deployed manually about 1 second later, reverse thrust was applied from 7 to 16 seconds after touchdown. Maximum wheelbrakes were applied manually about 8 seconds after touchdown and maximum brakes pressure was maintained throughout the roll out, but the crew immediately recognized the aircraft was skidding. About 9 seconds later, about 5500 feet past threshold, the aircraft veered left off the center line, the crew determined they would not be able to stop the aircraft on the runway and radioed tower, who in response pressed the crash alert to activate emergency services, the aircraft skidded about 2500 feet left of the center line then, about 400 feet short of the end of paved surface, veered right while further turning left, the aircraft exited paved surface at about 40 knots turning further and veering left and came to a stop about 350 feet past the end of paved surface and 60 feet to the left of the extended runway center line.

Emergency services reached the aircraft 3 minutes after touchdown and observed all 4 brakes were hot, the brakes were foamed, about 5 minutes later the temperature had dropped to 200 degrees F.

The aircraft sustained damage to the gear doors, lower fairing, trailing edges of flaps, the aft fuselage showed several dents and holes due to debris thrown up by the tyres. Engine #1 inlet was coated with dried mud, the low pressure compressor sustained damage from ingesting debris. All 4 brakes were damaged, all 4 main tyres had cuts, scrapes and patches of reverted rubber, 2 of the tyres burst at the flat spots.

Fragments of reverted rubber were collected from the runway from touchdown to stop position.

The TSB reported that the active runway was 16 with an 11 knots headwind component and 8 knots crosswind, concerned over turbulence on approach to runway 16 the captain however opted for the longer runway 11 with a 3 knots tailwind component and 14 knots crosswind.

The TSB reported that macrostructure as well as microstructure of the runway surface influece braking efficiency. While the friction of the macrostructure of the runway surface can be tested at a speed of 65 kph, the microstructure would be tested at a speed of 95 kph, the general recommendation is to conduct both tests for determining the braking efficiency and friction index. Transport Canada however only requires the macrostructure test but has no rules for microstructure tests.

None of the runways at St. John's were grooved.

The TSB analysed: "Although the exact depth of water could not be determined, the presence of water on the runway caused the aircraft to hydroplane, which led to a loss of directional control and braking ability, increasing the required stopping distance. This condition was exacerbated because the brakes were held on throughout the landing roll and the tires had excessive tread wear."

Three tyres were 80% worn, the fourth was 65% worn. This significantly reduced their wet runway friction values.

The TSB continued: "Aircraft landing performance on wet runways is a widely recognized safety concern. Grooved runways improve drainage thereby minimizing skids and drift, improve braking, and reduce the risk of hydroplaning. Studies have shown that wet, grooved runways often provide almost the same level of braking as on dry runways. The use of non-grooved runways increases the risk of wet runway overrun due to a reduction in braking characteristics."

The TSB analysed the brakes were hot after landing indicating that the brakes had worked and the antiskid system had been operating.

The TSB went on: "While it is understood that measuring the effects of water on runways presents certain challenges, the lack of clearly defined RSC reporting standards related to water on runways increases the risk of hydroplaning."

The TSB further analysed that the operator had a safety management system (SMS) in place however failed to introduce clear guidelines as to what had to be reported to the SMS, the employees thus were unclear what to report. In addition, the operator did not review earlier occurrences of hydroplaning at St. John's and thus missed an opportunity to avoid the runway overrun.

The airport of St. Johns introduced an enhanced friction measurement procedure as result of the investigation, the operator took 2 safety actions as result, too.
Incident Facts

Date of incident
Jul 16, 2011

Classification
Incident

Aircraft Type
Boeing 727-200

ICAO Type Designator
B722

This article is published under license from Avherald.com. © of text by Avherald.com.
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