Airport Operations

easily be aware of your presence when they are expecting Character Morse Code Telephony Phonic Pronunciation the standard radio calls. AAa BB Air Traffic Control (ATC) Services b C C c Besides the services provided by an FSS as discussed in DDd Chapter 12, “Aviation Weather Services,” numerous other EEe services are provided by ATC. In many instances a pilot is required to have contact with ATC, but even when not FF f required, a pilot may find their services helpful. GGg hH h Primary Radar II Radar is a device that provides information on range, azimuth, i JJj and/or elevation of objects in the path of the transmitted pulses. It measures the time interval between transmission and KKk reception of radio pulses and correlates the angular orientation LL L of the radiated antenna beam or beams in azimuth and/or MMm elevation. Range is determined by measuring the time it takes NNn for the radio wave to go out to the object and then return to the OO receiving antenna. The direction of a detected object from a o radar site is determined by the position of the rotating antenna P Pp when the reflected portion of the radio wave is received. QQq R R r Modern radar is very reliable and there are seldom outages. SSs This is due to reliable maintenance and improved equipment. TTt There are, however, some limitations that may affect ATC U services and prevent a controller from issuing advisories Uu concerning aircraft that are not under his or her control and VVv cannot be seen on radar. WWw XXx The characteristics of radio waves are such that they normally YYy travel in a continuous straight line unless they are “bent” by Z atmospheric phenomena, such as temperature inversions, Z z reflected or attenuated by dense objects such as heavy clouds 11 1 and precipitation, or screened by high terrain features. Radar 222 signals degrade over distance, cannot penetrate through solid 33 objects such as mountains, and the fastest radar updates every 3 444 4.7 seconds. By contrast, the satellite signals used with Automatic Dependent Surveillance−Broadcast (ADS−B) do 555 not degrade over distance, provide better visibility around N6n mountainous terrain and allows equipped aircraft to update O7 o their own position once a second with better accuracy. P8p Q 9q ATC Radar Beacon System (ATCRBS) R0 The ATC radar beacon system (ATCRBS) is often referred to r as “secondary surveillance radar.” This system consists of three components and helps in alleviating some of the limitations Figure 14-41. Phonetic alphabet. associated with primary radar. The three components are an interrogator, transponder, and radarscope. The advantages of If radio communication is lost, it may be a prudent decision ATCRBS are the reinforcement of radar targets, rapid target to land at a non-towered airport with lower traffic volume, if identification, and a unique display of selected codes. practical. When operating at a non-towered airport, no radio communication is necessary. However, pilots should be extra Growing air traffic in the National Airspace System (NAS) vigilant when not using the radio. Other traffic may not as will be addressed through the use of ADS-B, which not only 14-24