Definition

Braking Action Reports are reports made by pilots on the deceleration and directional control they perceive as they stop aircraft on runways contaminated by standing water, slush, snow, or ice.

Description

Rain, snow, and ice affect the braking action and controllability of aircraft attempting to slow down and stop. The International Civil Aviation Organization (ICAO) has adopted a standardized system for reporting the condition of runways to pilots, and for pilots to report the resulting braking action. This overall system is called the Runway Condition Assessment Matrix (RCAM).

Within the RCAM, Runway Condition Codes (RCC), ranging from 6 to 0, report the condition of the runway surface. A dry runway is indicated by a 6. A wet runway, or a runway with light snow or slush, is indicated by a 5. Compacted snow is indicated by a 4. Higher levels of dry or wet snow are indicated by a 3. Slush and standing water are indicated by a 2. Ice is indicated by a 1. Wet ice or water on top of compacted snow is indicated by a 0. Aircraft performance calculations take these readings into account when determining factors such as required landing distance.

The RCAM also includes standard terminology for pilots to report braking action. No report verbiage is established for a dry runway. For a wet runway, or a runway with light slush or snow, with an RCC of 5, pilots are to report “GOOD” braking action if deceleration is normal for the braking effort applied, AND the directional control is normal. For a runway with compacted snow and an RCC of 4, pilots are to report “GOOD TO MEDIUM” if deceleration OR directional control is between Good and Medium, with only a slight reduction in effectiveness. For a runway with snow depths of more than three millimeters, or with other conditions that meet an RCC of 3, pilots are to report “MEDIUM” braking action if deceleration or directional control are noticeably reduced. For a runway contaminated with more than a three-millimeter depth of slush or standing water, with an RCC of 2, pilots are to report “MEDIUM TO POOR” for the reduced deceleration or directional control. For icy runways with an RCC of 1, pilots are to report “POOR” braking action if deceleration or directional control is significantly reduced. For runways with wet ice, water over compacted snow, or snow over ice, with an RCC of 0, pilots are to report “LESS THAN POOR” braking action if deceleration is minimal to nonexistent or if directional control is uncertain.

RCC numbers are issued for each third of a given runway. So, for example, a wet runway with compacted snow along the last third would be reported as 5/5/4. Pilots receive these reports from the Automatic Terminal Information Service (ATIS).

RCAM aims to standardize braking action reporting and reduce its subjectivity. The system replaces earlier methods, including surface friction reports based on a value represented by the Greek letter Mu (pronounced “mew). Mu values ranged from 0 to 100, with 100 representing the greatest braking action. Generally, Muvalues were not reported unless they were 40 or less, and there was no official correlation between a given value and the expected braking action.