UK investigators are proposing that on-board aircraft data be exploited as a source of runway friction information, following an inquiry into a series of wet-weather landing incidents at Bristol Airport.

The Air Accidents Investigation Branch (AAIB) is recommending that the European Aviation Safety Agency (EASA) research the feasibility of measuring aircraft braking friction with respect to runway position.

EASA should also develop methods, it adds, for sharing the information on a timely basis.

Three aircraft landing at Bristol on 29 December 2006 experienced poor braking or lateral control problems. Two of them - an Aurigny Air Services ATR 72 and a British Airways CitiExpress Embraer ERJ-145 - were unable to stay on the runway during their roll-out. The ATR suffered propeller damage.

Resurfacing work at Bristol meant some of the manoeuvring areas, including a 295m (968ft) central section of the runway, had temporary surfaces of ungrooved asphalt.

Various friction problems had been reported from 14 November, six weeks before the serious incidents that prompted the inquiry, but the surface friction of the ungrooved section was not properly assessed. The AAIB says it had "significantly less friction" than the grooved areas, and was probably below minimum friction levels.

Braking reports based on continuous friction measuring equipment, it adds, gave flight crews "false confidence" of braking action available on the wet runway.

The third aircraft involved in the 29 December incidents, an XL Airways Boeing 737-800, also experienced poor stopping performance at Bristol five days later.

Bristol Airport's operator subsequently closed the runway and grooved the temporary surface. After the runway re-opened, on 8 January 2007, no further braking difficulties were reported.

Source: Air Transport Intelligence news