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The term Runway Maintenance is usually used to refer to activity required to keep the runway in a safe condition for aircraft use. Whilst this self evidently means making sure that the integrity of the top surface is absolute, it is also defined in terms of minimum surface friction.
Runway Occupancy for Surface Maintenance Purposes
The necessary occupancy for runway maintenance activity is achieved by access when a runway is scheduled for closure anyway such as overnight, or for longer periods during which part or all of a runway is taken out of service. If a runway is going to be unavailable when an airport is open then a NOTAM must be used to advise accordingly. Whilst such NOTAMS are available in Airport Flight Briefing facilities and, increasingly, online, many larger aircraft operators take responsibility for making their flight crew aware of relevant NOTAMS through their own directly-provided procedure or an equivalent sub contract service provision.
The Maintenance Process
The integrity of runway surfaces is assured by regular inspections. Pavement maintenance requires periodic renewal of the top or wearing surface. The interval between surface re-making will vary according to the type of surface. The most commonly used hard surface types are concrete and asphalt. To aid surface water dispersal, the former is frequently grooved laterally to allow surface water to drain in the grooves and the latter employ a porous top layer, which allows surface water to run off below the surface rather than across it. Certain types of asphalt can also be grooved. Minor repairs such as joint re-sealing, crack stopping and the removal of rubber deposits from the TDZ may need relatively little continuous occupancy time but major works will either involve complete or partial runway closure for a continuous period of several weeks or a carefully managed programme of night closures during which a complex resurfacing programme can be progressively accomplished. In such cases, the friction characteristics of various parts of the available surface may vary on a daily basis which will invite very careful pre flight attention to NOTAM information, especially if adverse weather conditions may occur.
Risk Management and Runway Maintenance
There is a long history of accidents and serious Runway Excursion incidents which have especially occurred during take off or attempted take off as a result of a lack of flight crew awareness of the temporary closure of part of all of a runway to facilitate runway maintenance. It demonstrates that the lessons of proper pre flight briefing on runway availability and on positive Runway Identification have still to be learned.
Accidents and Incidents
- B744, Taipei Taiwan, 2000 (On 31 October 2000, the crew of a Singapore Airlines Boeing 747-400 taxiing for a night departure at Taipei in reduced (but not 'low') visibility with an augmenting crew member present on the flight deck failed to follow their correctly-confirmed taxi instructions and commenced take off on a partially closed runway. The subsequent collision with construction equipment and resultant severe post crash fire destroyed the aircraft killing over half the 170 occupants and injured 71 others. All three flight crew survived.)
- B738, Manchester UK, 2003 (On 16 July 2003, a Boeing 737-800, being operated by Excel Airlines on a passenger flight from Manchester to Kos began take off on Runway 06L without the flight crew being aware of work in progress at far end of the runway. The take off calculations, based on the full runway length resulted in the aircraft passing within 56 ft of a 14 ft high vehicle just after take off.)
- A343, Changi Singapore, 2007 (On 30 May 2007, at about 0555 hours local time, the crew of an Airbus A340-300 had to apply (Take-off Go Around) power and rotate abruptly at a high rate to become airborne while taking off from Runway 20C at Singapore Changi Airport, when they noticed the centreline lights were indicating the impending end of the available runway. The crew had calculated the take-off performance based on the full TORA (Take-off Run Available) of 4,000 m because they were unaware of the temporary shortening of Runway 20C to 2,500 m due to resurfacing works.)