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METAR runway state group coding

Runway States

Coding Requirements

General format: DRDRCEttBB

Where

DRDR is the runway designator

C is the runway deposits designator

E is the extent of contamination

tt is the depth of the deposit

BB is the friction coefficient or braking action

When runways are affected by snow, slush or other contaminants, an encoded runway state report for each runway in use is required to be appended to METARs. Ideally, a new report should be prepared for each change. If a report is not received, the previous message may be repeated once, although it is important that repeated messages are kept to a minimum.

If a runway inspection is not possible, it is preferable to report changes by general assessment rather than let a clearly unrepresentative message be repeated, for example, when:

a) Snow is judged to be turning to slush.

Thunderstorm RETS

Freezing rain REFZRA

Freezing drizzle REFZDZ

Moderate or heavy rain RERA

Moderate or heavy snow RESN

Moderate or heavy drizzle REDZ

Moderate or heavy ice pellets REPL

Moderate or heavy snow grains RESG

Moderate or heavy showers of rain RESHRA

Moderate or heavy showers of snow RESHSN

Moderate or heavy shower of small hail RESHGS

Moderate or heavy showers of snow pellets RESHGS

Moderate or heavy showers of hail RESHGR

Moderate or heavy blowing snow REBLSN

Sandstorm RESS

Dust storm REDS

Funnel cloud REFC

Volcanic ash REVA

b) It is apparent that snow depth has increased/decreased.

c) It is considered that braking action is deteriorating.

Appropriate local arrangements should be in place to ensure that a runway state message is available to the observer in good time for insertion into the next METAR.

NOTE: Data used to compile the runway state group is commonly provided by the aerodrome authority.

The depth of the deposit reported should be the average of the readings for the usable length of the runway.


Examples of METAR runway state group coding

a) 99421594 A repetition of the last message because no new information received, dry snow is covering 11% to 25% of the runway to a depth of 15 millimetres. Braking action is medium or good.

b) SNOCLO The aerodrome is closed due to contamination of the runways.

c) 74692225 Runway 24 right has slush covering 51% to 100% of the runway to a depth of 22 millimetres. The friction coefficient has been measured and is 25%.

d) 88CLRD95 Contamination has been cleared from all runways and the braking action is good.


Table  Runway state group coding for use in the METAR

DRDR Runway designator

27 = Runway 27 or 27L

77 = Runway 27R (50 added for ‘right’)

88 = All runways

99 = A repetition of the last message because no new information received

C Runway deposits

0 = Clear & dry

1 = Damp

2 = Wet

3 = Rime or frost covered

4 = Dry snow

5 = Wet snow

6 = Slush

7 = Ice

8 = Compacted or rolled snow

9 = Frozen ruts or ridges

/ = Not reported due to runway clearance in progress

E Extent of contamination

1 = 10% or less

2 = 11% to 25%

5 = 26% to 50%

9 = 51% to 100%

/ = Not reported due to runway clearance in progress

tt Depth of deposit

00 = <1mm

01 = 1mm etc

thru’ to

90 = 90mm

91 = not used

92 = 10cm

93 = 15cm

94 = 20cm

95 = 25cm

96 = 30cm

97 = 35cm

98 = 40cm or more

99 = Runways non operational due snow or clearance

// = Not measurable or not significant

BB Friction coefficient / Braking action

28 = Friction coefficient 28%

35 = Friction coefficient 35%

or

91 = Braking action poor

92 = Braking action med/poor

93 = Braking action medium

94 = Braking action med/good

95 = Braking action good

99 = Figures unreliable

// = not reported e.g. runway closed

If the aerodrome is closed due to contamination of runways, the abbreviation SNOCLO is used in place of a runway state group.

If contamination ceases to exist, the abbreviation CLRD is used between 88 and braking action.

 

This site was last updated 02/22/10