5.5 Radio Communication and Frequencies

Aviation Radio for Drone Pilots

A Part 107 Remote PIC is not required to hold a radio operator certificate or transmit to Air Traffic Control. Even so, understanding aviation radio improves situational awareness near airports, helps you coordinate during an emergency, and answers a predictable cluster of exam questions about frequencies, time, and phraseology.

The VHF Band and Line-of-Sight

Very High Frequency (VHF) is the workhorse band for civil aviation:

• Communication: 118.000 MHz to 136.975 MHz
• Navigation aids (VOR/ILS): 108.000 MHz to 117.950 MHz

VHF is line-of-sight, meaning terrain, the curvature of the earth, and distance all limit its range — two stations must essentially "see" each other. That property is why a low-altitude ground transmitter has limited reach and why aircraft, being higher, hear traffic from much farther away.

Key Frequencies

121.5 MHz is the single most-tested frequency — it is the international emergency (Guard) frequency monitored by Air Traffic Control facilities, reserved for genuine distress.

CTAF and ATIS

The Common Traffic Advisory Frequency (CTAF) is the frequency pilots use to self-announce position and intentions at and around a non-towered airport. It is printed on sectional charts and in the Chart Supplement (formerly the Airport/Facility Directory). Monitoring CTAF is one of the best free situational-awareness tools when you fly near an untowered field.

The Automatic Terminal Information Service (ATIS) is a continuous looped broadcast of current airport information — wind, visibility, sky condition, temperature, dew point, altimeter setting, active runway, and pertinent NOTAMs. Each update carries a phonetic letter (Information Alpha, Bravo, Charlie). A pilot calling the tower will state which letter they have, confirming they heard the latest data.

The Phonetic Alphabet

The NATO phonetic alphabet standardizes spoken letters so they survive a noisy radio.

Numbers are spoken to avoid confusion: 0 = "zero," 3 = "tree," 4 = "fow-er," 5 = "fife," 9 = "niner," and a decimal is "point."

UTC / Zulu Time

Every aviation time stamp is reported in Coordinated Universal Time (UTC), also called Zulu time and marked with a trailing Z. UTC never shifts for daylight saving, so it removes time-zone ambiguity from METARs, TAFs, NOTAMs, and flight plans.

To convert, add the offset to your local hour: Eastern Standard adds 5, Eastern Daylight adds 4, Pacific Standard adds 8. Always work weather and NOTAM times in Zulu, then convert to local for your own planning. A frequent test item gives a METAR observation time in Zulu and asks for the local equivalent, or vice versa — practice the arithmetic in both directions so a daylight-saving offset does not trip you up.

Do Drone Pilots Need a Radio?

No Part 107 rule requires a Remote PIC to carry, monitor, or transmit on an aviation radio, and a routine Part 107 flight does not involve talking to a control tower the way a manned pilot does. Authorization to enter controlled airspace is obtained ahead of time through LAANC or a DroneZone request, not by a radio call. Where a radio adds value is situational awareness: a handheld aviation receiver tuned to the local CTAF lets you hear an aircraft announce a position and intentions near a non-towered field, giving you seconds of warning to descend and yield.

If you do transmit, remember the airwaves are a shared safety resource — never block the frequency with non-essential chatter, and reserve 121.5 MHz strictly for genuine distress.

Reading an ATIS Broadcast

Because the Automatic Terminal Information Service packs a lot into one loop, knowing its order helps you extract what matters. A typical broadcast names the airport and the information letter, then gives the time of the weather observation in Zulu, wind (direction in degrees magnetic and speed in knots), visibility, sky condition, temperature and dew point in Celsius, the altimeter setting, the active runway(s), and any notices. For a drone pilot, the wind and visibility lines confirm whether the Part 107 weather minimums are met, and the observation time tells you how current the data is.

For the Exam: Memorize that 121.5 MHz is the emergency frequency, aviation communication lives in the VHF 118-137 MHz line-of-sight band, all times are UTC/Zulu, and the phonetic alphabet plus number pronunciation are standard. Monitoring CTAF and ATIS is the practical takeaway for flying near airports.