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Braking Action & Runway Friction Reports & Advisories

Introduction:

  • Friction is defined as the ratio of the tangential force needed to maintain uniform relative motion between two contacting surfaces to the perpendicular force holding them in contact
    • Simply stated, friction quantifies slipperiness of pavement surfaces

Braking Action Reports and Advisories:

  • When available, ATC furnishes pilots the quality of braking action received from pilots
    • The quality of braking action is described by the terms "good," "good to medium," "medium," "medium to poor," "poor," and "nil"
    • When pilots report the quality of braking action by using the terms noted above, they should use descriptive terms that are easily understood, such as, "braking action poor the first/last half of the runway," together with the particular type of aircraft
  • FICON NOTAMs will provide contaminant measurements for paved runways; however, a FICON NOTAM for braking action will only be used for non-paved runway surfaces, taxiways, and aprons
    • These NOTAMs are classified according to the most critical term ("good to medium," "medium," "medium to poor," and "poor")
      • FICON NOTAM reporting of a braking condition for paved runway surfaces is not permissible by Federally Obligated Airports or those airports certificated under 14 CFR Part 139
      • A "NIL" braking condition at these airports must be mitigated by closure of the affected surface. Do not include the type of vehicle in the FICON NOTAM
  • When tower controllers receive runway braking action reports which include the terms medium, poor, or nil, or whenever weather conditions are conducive to deteriorating or rapidly changing runway braking conditions, the tower will include on the ATIS broadcast the statement, "BRAKING ACTION ADVISORIES ARE IN EFFECT"
  • During the time that braking action advisories are in effect, ATC will issue the most recent braking action report for the runway in use to each arriving and departing aircraft
    • Pilots should be prepared for deteriorating braking conditions and should request current runway condition information if not issued by controllers. Pilots should also be prepared to provide a descriptive runway condition report to controllers after landing

Runway Friction Reports and Advisories:

  • Aircraft braking coefficient is dependent upon the surface friction between the tires on the aircraft wheels and the pavement surface
    • Less friction means less aircraft braking coefficient and less aircraft braking response
  • Runway condition code (RwyCC) values range from 1 (poor) to 6 (dry)
    • For frozen contaminants on runway surfaces, a runway condition code reading of 4 indicates the level when braking deceleration or directional control is between good and medium
    • A RwyCC of “0” is used to delineate a braking action report of NIL and is prohibited from being reported in a FICON NOTAM
  • Airport management should conduct runway condition assessments on wet runways or runways covered with compacted snow and/or ice
    • Numerical readings may be obtained by using the Runway Condition Assessment Matrix (RCAM)
    • The RCAM provides the airport operator with data to complete the report that includes the following:
      • Runway(s) in use
      • Time of the assessment
      • Runway condition codes for each zone (touchdown, mid-point, roll-out)
      • Pilot-reported braking action report (if available)
      • The contaminant (for example, wet snow, dry snow, slush, ice, etc.)
    • Assessments for each zone (see 4−3−9c1(c)) will be issued in the direction of takeoff and landing on the runway, ranging from “1” to “6” to describe contaminated surfaces
      • A RwyCC of “0” is used to delineate a braking action report of NIL and is prohibited from being reported in a FICON NOTAM
    • When any 1 or more runway condition codes are reported as less than 6, airport management must notify ATC for dissemination to pilots
    • Controllers will not issue runway condition codes when all 3 segments of a runway are reporting values of 6
  • When runway condition code reports are provided by airport management, the ATC facility providing approach control or local airport advisory must provide the report to all pilots
  • Pilots should use runway condition code information with other knowledge including aircraft performance characteristics, type, and weight, previous experience, wind conditions, and aircraft tire type (such as bias ply vs. radial constructed) to determine runway suitability
  • The Runway Condition Assessment Matrix identifies the descriptive terms "good," "good to medium," "medium," "medium to poor," "poor," and "nil" used in braking action reports
Major Migratory Flyways, U.S. Fish and WIldlife Service
Figure 1: Runway Condition Assessment Matrix (RCAM)

Conclusion:

  • Pilots are responsible for advising ATC about breaking conditions

References: