FAA Asks Operators to Increase Safety Margins When Landing on Wet Runways

Sept. 22, 2015

A recent FAA Safety Alert for Operators (SAFO) emphasizes the need for flight crews to take a conservative approach when landing on water-slickened surfaces, going beyond the manufacturer’s published landing distances and advisory data, and even the agency’s own prior guidance on the matter.

Last year, the FAA published Advisory Circular 91-79A, which offered information to assist pilots with identifying, understanding and mitigating the risk factors that lead to runway overruns on landing. That was followed by a SAFO calling on turbojet aircraft operators to add a margin of at least 15 percent above the manufacturer’s published dry-runway landing distances when landing on wet runways.

In many cases, though, even that allowance may not provide adequate stopping margins under all conditions. “When determining published landing distances, the manufacturer was trying to hit the absolute, best-case numbers,” noted Ben Kohler, lead member of the Technical Excellence Working Group of NBAA’s Safety Committee and a Dassault 2000EX and Gulfstream GIV-SP captain.

“That generally means crossing the threshold at 50 feet, at Vref and applying maximum braking immediately after touchdown,” Kohler explained. “If you actually operated like that, however, the passengers in back likely would never fly with you again.”

For single-plane/single-pilot operators and small flight departments, Kohler suggested emulating the best practices of larger flight departments, not only in planning greater margins when landing on wet or contaminated runways, but also in looking for additional opportunities to incorporate similar safety guidelines throughout other phases of their operations.

“Such an approach extends from preflight planning, to incorporating more conservative performance margins (minimum runway length or width, maximum crosswind, etc.), post-flight debriefings and gathering feedback from crews regarding the effectiveness of planned mitigations for a given flight,” said Kohler.

Additionally, a guide being drafted by the Technical Excellence Working Group will assist operators in developing these practices, as well as incorporating case studies and performance problems to generate discussions at flight department safety meetings.

“Without question, we all must work harder to prevent runway excursions,” he concluded. “The Flight Safety Foundation examined 14 years of accident data for commercial aircraft and found that 30 percent of those accidents involved runway operations. Of those, 97 percent involved a runway overrun. That’s a big chunk, and the risk factors apply to other aircraft types, as well.”

Review the FAA SAFO: “Turbojet Braking Performance on Wet Runways.” (PDF)