Description

On 25 November 2010, a Boeing 737-800 being operated by Thompson Airways on a passenger fight from Arrecife, Lanzarote to Newcastle UK marginally overran Runway 07 at destination onto the paved stopway during a night landing in normal ground visibility. None of the 197 occupants were injured and the aircraft was undamaged. Passengers were disembarked to buses for transport to the terminal. An acceptable disposition of frozen deposits had been advised as present on the runway prior to the approach after a sweeping operation had been conducted following a discontinued approach ten minutes earlier because of advice from ATC that the runway was contaminated with wet snow.

Investigation

A Field Investigation was carried out by the UK AAIB. Useful Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) data were available to assist the Investigation with the CVR recording having been stopped promptly after the accident.

It was found that with the aircraft in its final stopping position, the nose landing gear had remained on the 15 metre long paved stopway surface which extended for a distance of 3 metres beyond the marked runway end. The runway had been described just prior to landing as ‘WET’ throughout its full length with a 2mm depth of wet snow present.

It was noted that the First Officer had been PF and that the LDA had been calculated as 300 metres greater than the 2209 metre LDA. This calculation took account of the reported runway surface condition for landing. FDR data showed that the aircraft had touched down at a normal speed approximately 450 m from the Runway 07 threshold which is approximately 150 m beyond the optimum touchdown point and would have increased the LDR. Initially, deceleration had appeared normal but, in the latter stages of the landing run, deceleration had reduced despite the application of full manual braking. At 50 knots, the aircraft commander took control when he perceived a risk of an overrun occurring.

The Investigation team were advised by the two pilots that upon leaving the aircraft after the overrun, both of them had independently walked on the runway back towards the Runway 25 displaced threshold and assessed the surface as “very icy”.

It was noted that on a runway contaminated with other than frozen deposits, UK procedures do not permit the communication of measured braking action to pilots derived from CFME devices, only the measured or estimated depth of contamination. If the option of taking actual measurement of the depth of contaminant is utilised, procedures require the use of a mechanical device which must be stood vertically on the runway surface penetrating the contaminant layer so that a coaxial disc can then be lowered onto the upper surface of the contaminant and the depth above the runway surface read off in mm. Measurements every 300 metres along a runway at 5-10 metres each side of the centreline are prescribed in these procedures. There was self-evidently insufficient time for this process to take place prior to the overrun landing – the Investigation noted that to comply with the depth measurement regime, the device operator would need to disembark any vehicle being used for transit a total of 18 times to measure and fully assess the 2329 metre length of runway 07 at Newcastle. It was noted that touchdown had been made with a slight tail wind component, which had been similar to that reported on the Automatic Terminal Information Service (ATIS) current shortly before the overrun occurred.

The Investigation considered that because the depth and type of contaminant on the runway had in this case been visually assessed, that there had been the potential for a slight but critical difference between the actual and reported surface conditions. In addition, it was considered that other factors that may have had an adverse effect on the actual versus expected landing distance besides the slightly late touchdown were the selection of reverse thrust to idle before a safe stop was assured and the decision prior to landing not to use maximum autobrake on the grounds that it was “not necessary”

It was noted that all methods available to the crew at the time of the event which might have enabled them to gauge the likely braking action after landing on a runway at the time of the event were based on correlations between type and depth of contaminant and expected braking action.

It was also noted that UK CAA had current documentation giving two contradictory definitions of ‘contamination’ of runway surfaces.

The Conclusion of the Investigation was as follows:

“The aircraft entered the stopway of Runway 07 at Newcastle Airport because the braking action on the runway was less than the pilots had anticipated. It is possible that there was a significant difference between the actual and reported conditions because the depth and type of contaminant on the runway was assessed visually. Touchdown of the aircraft beyond the normal touchdown zone, and selection of idle reverse thrust before the aircraft was at taxi speed, may have contributed to an increased landing distance.”

Two Safety Recommendations were made a a result of the Investigation:

• That the CAA publishes a single definition of Contaminated Runways. [2011-087]

• That the CAA develops a system of contaminant depth measurement that provides accurate and timely runway contamination information to enable pilots to determine the landing distance required. [2011-088]

The Final Report of the Investigation AAIB Bulletin: 2/2012 EW/C2010/11/05 was published on 9 February 2012.

Further Reading

• Runway Excursion
• Landing on Contaminated Runways
• Runway Surface Friction
• Beyond the Runway End Safety Area
• Runway Availability
• Pilot Perception
• Situational Awareness