11.2 The Greek letter MU (pronounced “myew”), is used to designate a friction value representing runway surface conditions.
11.3 MU (friction) values range from 0 to 100 where zero is the lowest friction value and 100 is the maximum friction value obtainable. For frozen contaminants on runway surfaces, a MU value of 40 or less is the level when the aircraft braking performance starts to deteriorate and directional control begins to be less responsive. The lower the MU value, the less effective braking performance becomes and the more difficult directional control becomes.
11.4 At airports with friction measuring devices, airport management should conduct friction mea-surements on runways covered with compacted snow and/or ice.
11.4.1 Numerical readings may be obtained by using any FAA approved friction measuring device. As these devices do not provide equal numerical readings on contaminated surfaces, it is necessary to designate the type of friction measuring device used.
11.4.2 When the MU value for any one-third zone of an active runway is 40 or less, a report should be given to ATC by airport management for dissemination to pilots. The report will identify the runway, the time of measurement, the type of friction measuring device used, MU values for each zone, and the contaminant conditions; e.g., wet snow, dry snow, slush, deicing chemicals, etc. Measurements for each one-third zone will be given in the direction of takeoff and landing on the runway. A report should also be given when MU values rise above 40 in all zones of a runway previously reporting a MU below 40.
11.4.3 Airport management should initiate a NO-TAM(D) when the friction measuring device is out of service.
11.4.4 When MU reports are provided by airport management, the ATC facility providing approach control or local airport advisory will provide the report to any pilot upon request.
11.4.5 Pilots should use MU information with other knowledge including aircraft performance character-istics, type, weight, previous experience, wind conditions, and aircraft tire type (i.e., bias ply vs. radial constructed) to determine runway suitability.
11.4.6
No correlation has been established between MU values and the descriptive terms “good,” “fair,” “poor,” and “nil” used in braking action reports.
12.
Communications Prior to Departure
12.1 Nontower Controlled Airports
12.1.1 At airports not served by a FSS located on the airport, the pilot in command should broadcast his/her intentions on the prescribed frequency prior to aircraft movement and departure.
12.1.2 At airports served by a FSS located on the airport, the pilot in command should obtain airport advisory service prior to aircraft movement and departure.
12.1.3 Aircraft departing on an IFR clearance must obtain the clearance prior to departure via telephone, the appropriate FSS, or via direct communications with the ATC facility issuing the clearance as appropriate. An IFR clearance does not relieve the pilot from the communication stated above prior to aircraft movement and departure.
12.2 Tower Controlled Airports
12.2.1 Pilots of departing aircraft should communi-cate with the control tower on the appropriate ground control/clearance delivery frequency prior to starting engines to receive engine start time, taxi, and/or clearance information. Unless otherwise advised by the tower, remain on the frequency during taxiing and run up, then change to local control frequency when ready to request takeoff clearance.
NOTE.
Refer to Automatic Terminal Information Service (ATIS) for continuous broadcast of terminal information.
13. Gate Holding Due to Departure Delays
13.1 Pilots should contact ground control/clearance delivery prior to starting engines as gate hold procedures will be in effect whenever departure delays exceed or are anticipated to exceed 15 minutes. The sequence for departure will be maintained in accordance with initial call up unless modified by flow control restrictions. Pilots should monitor the ground control/clearance delivery frequency for engine startup advisories or new proposed start time if the delay changes.
Federal Aviation Administration Twentieth Edition
13.2
The tower controller will consider that pilots of turbine.powered aircraft are ready for takeoff when they reach the runway/warm.up block unless advised otherwise.
14.
Taxiing
14.1 General. Approval must be obtained prior to moving an aircraft or vehicle onto the movement area during the hours an airport traffic control tower is in operation.
14.1.1 Always state your position on the airport when calling the tower for taxi instructions.
14.1.2 The movement area is normally described in local bulletins issued by the airport manager or control tower. These bulletins may be found in FSSs, fixed base operators offices, air carrier offices, and operations offices.
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