It is important for a pilot to know the direction of the wind. At facilities with an operating control tower, this information is provided by ATC. Information may also be provided by FSS personnel located at a particular airport or by requesting information on a common air traffic frequency (CTAF) at airports which have the capacity to receive and broadcast on this frequency.
 When none of these services are available, it is possible to determine wind direction and runway in use by visual wind indicators. A pilot should check these wind indicators even when information is provided on the CTAF at a given airport because there is no assurance that the information provided is accurate.
 

Wind direction indicators include a wind sock, wind tee, or tetrahedron. These are usually located in a central location near the runway and may be placed in the center of a segmented circle which will identify the traffic pattern direction if it is other than the standard left-hand pattern. [Figures 6-11 and 6-12] The wind sock is a good source of information since it not only indicates wind direction, but allows the pilot to estimate the wind velocity and gust. The wind sock extends out straighter in strong winds and will tend to move back and forth when the wind is

gusty. Wind tees and tetrahedrons can swing freely, and will align themselves with the wind direction. The wind tee and tetrahedron can also be manually set to align with the runway in use, therefore a pilot should also look at the wind sock if available.
 

RADIO COMMUNICATIONS Operating in and out of a controlled airport, as well as in a good portion of the airspace system, requires that an aircraft have two-way radio communication capability. For this reason, a pilot should be knowledgeable of radio station license requirements and radio communications equipment and procedures. Radio License  There is no license requirement for a pilot operating in the United

States; however, a pilot who operates internationally is required to hold a restricted radiotelephone permit issued by the Federal Communications Commission (FCC). There is also no station license requirement for most general aviation aircraft operating in the United States. A station license is required however for an aircraft which is operating internationally, which uses other than a very high frequency (VHF) radio, and which meets other criteria.
 

Figure 6-13.—Phonetic alphabet.

Radio Equipment

 In general aviation, the most common types of radios are VHF. A VHF radio operates on frequencies between 118.0 and 136.975 and is classified as 720 or 760 depending on the number of channels it can accommodate. The 720 and 760 uses .025 spacing (118.025, 118.050, etc.) with the 720 having a frequency range up to 135.975 and the 760 going up to 136.975. VHF radios are limited to line of sight transmissions; therefore, aircraft at higher altitudes are able to transmit and receive at greater distances.

Radio Procedures

 Using proper radio phraseology and procedures will contribute to a pilot’s ability to operate safely and efficiently in the airspace system. A review of the Pilot/Controller Glossary contained in the Aeronautical Information Manual (AIM) will assist a pilot in the use and understanding of standard terminology. The AIM also contains many examples of radio communications which should be helpful.

 The International Civil Aviation Organization (ICAO) has adopted a phonetic alphabet which should be used in radio communications. When communicating with ATC, pilots should use this alphabet to identify their aircraft. [Figure 6-13]

Lost Communication Procedures

 It is possible that a pilot might experience a malfunction of the radio. This might cause the transmitter, receiver, or both to become inoperative. If a receiver becomes inoperative and a pilot needs to land at a controlled airport, it is advisable to remain outside or above Class D airspace until the direction and flow of traffic is determined. A pilot should then advise the tower of the aircraft type, position, altitude, and intention to land. The pilot should then continue and enter the pattern, report his or her position as appropriate, and watch for light signals from the tower. Light signal colors and their meaning are contained in figure 6-14.

Figure 6-14.—Light gun signals. If the transmitter becomes inoperative, a pilot should follow the previously stated procedures and also monitor the appropriate air traffic frequency. During daylight hours air traffic transmissions may be acknowledged by rocking the wings, and at night by blinking the landing light.

 When both receiver and transmitter are inoperative, the pilot should remain outside of Class D airspace until the flow of traffic has been determined and then enter the pattern and watch for light signals.

 If a radio malfunctions prior to departure, it is advisable to have it repaired if possible. If this is not possible, a call should be made to air traffic and the pilot should request authorization to depart without two-way radio communications. If authorization is given to depart, the pilot will be advised to monitor the appropriate frequency and/or watch for light signals as appropriate.