Concerned by a spate of incidents in which commercial or corporate aircraft have "departed" airport paved surfaces during taxi, take off or landing, the US FAA has issued a safety alert calling on pilots, controllers and airport operators to better share winter hazard information.

The 16 incidents, which occurred between 17 December 2008 and 18 January this year, involved "factors such as loss of stopping capability, loss of steering control, speeds greater than surface friction conditions permitted, or reduced visibility of surface markings and signage", says the FAA in a safety alert for operators (SAFO) published on 11 February.

Common threads uncovered during the investigation of the events include flight crews not having the needed information about the surface conditions, airports not providing timely updates of information and controllers failing to understand the impact of contamination on runways and taxiways.

As a result, the agency is asking pilots to "consider contacting the airport directly" for updates on weather and ground conditions. When taxiing on a contaminated runway or taxiways, pilots are advised to slow the aircraft "to a fast walking speed". In slippery conditions, the FAA is recommending that crews "do not accept air traffic control (ATC) clearances to expedite taxiing or exit the runway sooner than prudent".

The FAA is recommending that airport operators report runway conditions "in a quick and timely manner" in changing weather conditions. "A few degrees of temperature variance can change an airport surface that had very good stopping and cornering friction to one that has little of no friction coefficient," the SAFO states.

Further, the FAA says airports, depending on their snow plan priorities, may only chemically treat runway centrelines, leaving runway sides and exist untreated.

Air traffic controllers too are reminded that "keeping field conditions and braking reports up to date is a vital function during inclement winter weather" and that traction and braking by aircraft "will likely be reduced" in winter weather.

"Operations in conditions of contaminated ramps, taxiways and runways are not 'ops normal,'" the SAFO states.

Source: Air Transport Intelligence news