Runway Condition Assessment Matrix - RCAM[PDF]
Following several runway excursions leading to fatal accidents in the last few years, a workgroup from the FAA has been formed in order to determine a course of action in the prevention of runway overrun and excursions, one of the main causes of fatal injuries in aviation accidents nowadays.
A matrix has been created to correlate the runway contamination versus the expected braking action.
See below the dramatic runway overrun of flight SWA1248 at Chicago Midway Airport in 2005:
Definitions used by the matrix
- standing water more than 3 mm deep;
- slush more than 3 mm deep;
- loose snow more than 20 mm deep;
- compacted snow or ice, including wet ice.
Given the preceding definition, a wet runway is not a contaminated runway.
- Snow (dry, compacted, wet)
- Water (standing water, slippery wet)
If a specific contaminant is not listed previously, there is no possible correlation between the expected and the actual braking actions.
Most of the time, operators will prohibit operations on such runways.
Find below the ICAO Runway Condition Assessment Matrix (RCAM) sorted by Runway Condition Code (RCC).
The determination of takeoff performances, specifically of the acceleration-stop performance, lies on a different computation which requires the selection of the contaminant.
|RCC||Runway surface description||Aeroplane control observation||Braking action|
Wet (less than 3 mm of water)
Less than 3 mm depth of:
|Braking deceleration is normal for the wheel braking effort applied
Directional control is normal.
|4||-15°C and colder Outside Air Temperature:
|Braking deceleration is not as good as expected for the wheel braking effort applied.
Directional control is not as good as expected.
|GOOD TO MEDIUM|
|3||Slippery when wet
Dry snow or wet snow over compacted snow
Greater than 3 mm depth of:
Warmer than -15°C Outside Air Temperature:
|Braking deceleration is noticeably reduced for the wheel braking effort applied.
Directional control is noticeably reduced.
|2||Greater than 3 mm depth of:
|Braking deceleration is reduced for the wheel braking effort applied.
Directional control is reduced.
|MEDIUM TO POOR|
|1||Ice||Braking deceleration is significantly reduced for the wheel braking effort applied.
Directional control is significantly reduced.
Slush over ice
Water over compacted snow
Dry snow or wet snow over ice
|Braking deceleration is minimal to non-existent for the wheel braking effort applied.
Directional control is uncertain.
|LESS THAN POOR / NIL|
For example, most operators and aircraft manufacturers will forbid runway operations when runway is considered runway condition code 0.
The term "FAIR" is not existing anymore in regard to braking action.
It has been replaced by the term "MEDIUM".
Recommendation to flight crew
Mu Friction Coefficient
For a while, airport operators were providing runway state by measuring the Mu Friction Coefficient.
In most cases, this friction coefficient underestimates the actual adverse consequences of the runway contamination. The sensors used such as vehicle braking were not reliable.
The runway contamination information should be communicated either by NOTAMs or SNOWTAMs using thirds of the runway length.
- Presentation to the ICAO of the FAA workgroup conclusions regarding runway condition assessment: https://www.icao.int/SAM/Documents/2019-GRF/19SAMGRF%20S1.4%20Alberto%20FAA%20(Background).pdf
- VID 200696 - Creation
DATE OF SUBMISSION
- 12:51, 23 February 2021
- This documentation is copyrighted as part of the intellectual property of the International Virtual Aviation Organisation.
- The content of this documentation is intended for aviation simulation only and must not be used for real aviation operations.