By The CTS Team on March 9, 2017
Category: Ground Operations

Runway Braking From Good to Nil: Contaminated Runway Safety

Runway operations continue to be one of the most vital safety-related topics for both the FAA and the aviation community at large. No matter the conditions, the most critical moments of flight occur on and around the runway, making good preparation and practice important. This is increased tenfold when the runway is slick or contaminated, adding additional factors to consider when making takeoff and landing performance and safety calculations.

Last October, the FAA introduced the Takeoff and Landing Performance Assessment, or TALPA, to help reduce the risk of runway overruns by implementing an improved system of measuring wet runway conditions for landings. One of the biggest changes in the initiative is the addition of more descriptive braking action codes and definitions to indicate the condition of a wet runway. It uses a mix of Assessment Criteria from airport operators on the ground and Control and Braking Assessment Criteria from pilots to describe runway conditions to others.

One of the most obvious differences between the old system and the new Runway Condition Assessment Matrix is the removal of the “Fair” descriptor and its replacement with “Medium”. Pilot condition reports have also become more nuanced. Instead of simply using one of the four descriptors (Good, Medium, Poor, or NIL), pilots can also use “Good to Medium” or “Medium to Poor” both as a more specific indicator of conditions and to bring runway reporting up to ICAO standards.

Simply reporting and understanding braking action reports isn’t enough, of course. A myriad of factors determine braking action on contaminated runways and how you, as a pilot, ought to handle the landing.

Braking action is not only affected by how wet or slick the runway is, though that plays a major role. Tire wear and inflation, anti-skid systems, the runway surface itself, and the amount and type of contaminant all are factors that must be taken into account. With low tire pressure, reduced tread, or large quantities of water, tires may not be able to expel enough water to maintain contact with the runway. When this happens, the aircraft may hydroplane, resulting in a loss of nosewheel steering, directional control, and reduced braking performance.

With wet runways, hydroplaning is all but guaranteed to occur to some small degree, but the majority of negative effects can be prevented. A firm, on-speed touchdown will reduce hydroplaning at its most critical moment, allowing the tires to establish traction and begin slowing down the aircraft.

Aircraft and company specific procedures for contaminated runway operations should be addressed in more depth during initial and recurrent training, as well as by periodically perusing related reading for a refresher.

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