5.5 Radio Communication and Frequencies
Key Takeaways
- 121.5 MHz is the emergency frequency — know this for the exam.
- All aviation times use UTC/Zulu time, not local time.
- CTAF at non-towered airports and ATIS at towered airports provide useful situational awareness.
- The NATO phonetic alphabet is standard for all aviation communication.
- VHF radio communication is line-of-sight and operates in the 118-137 MHz range.
5.5 Radio Communication and Frequencies
While Part 107 drone pilots are not required to communicate directly with ATC via radio, understanding aviation radio communication basics helps with situational awareness, emergency coordination, and exam questions.
Aviation Radio Basics
VHF (Very High Frequency) is the primary communication band for aviation:
- Range: 118.000 MHz to 136.975 MHz for communication
- Range: 108.000 MHz to 117.950 MHz for navigation aids
- VHF is line-of-sight — terrain and distance limit range
Key Frequencies
| Frequency | Purpose | When UAS Pilots Might Use |
|---|---|---|
| 121.5 MHz | Emergency frequency (Guard) | True emergencies — distress calls |
| 122.0 MHz | Flight Service Station (FSS) | Obtaining weather briefings |
| 122.9 MHz | Multicom (uncontrolled airports) | Self-announcing at non-towered airports |
| 123.025 MHz | Helicopter frequency | Monitor near heliports/hospitals |
| ATIS frequency | Automatic Terminal Information Service | Listen for current airport conditions |
| CTAF/Unicom | Common Traffic Advisory Frequency | Monitor traffic at non-towered airports |
CTAF (Common Traffic Advisory Frequency)
The CTAF is the frequency used by pilots to communicate at and around non-towered airports:
- Found on sectional charts and in the Chart Supplement (Airport/Facility Directory)
- Pilots self-announce their position and intentions
- Monitoring CTAF near non-towered airports provides excellent situational awareness for drone pilots
ATIS (Automatic Terminal Information Service)
ATIS broadcasts current weather and airport information on a continuous loop:
- Updated approximately every hour or when conditions change significantly
- Each update is designated by a phonetic letter (Alpha, Bravo, Charlie, etc.)
- Contains: wind, visibility, sky condition, temperature, dew point, altimeter setting, active runways, NOTAMs
- ATIS frequency is shown on sectional charts in the airport data block
Phonetic Alphabet
The NATO phonetic alphabet is used in all aviation communication:
| Letter | Phonetic | Letter | Phonetic |
|---|---|---|---|
| A | Alpha | N | November |
| B | Bravo | O | Oscar |
| C | Charlie | P | Papa |
| D | Delta | Q | Quebec |
| E | Echo | R | Romeo |
| F | Foxtrot | S | Sierra |
| G | Golf | T | Tango |
| H | Hotel | U | Uniform |
| I | India | V | Victor |
| J | Juliet | W | Whiskey |
| K | Kilo | X | X-ray |
| L | Lima | Y | Yankee |
| M | Mike | Z | Zulu |
Number pronunciation in aviation:
- 0 = Zero, 1 = Won, 2 = Too, 3 = Tree
- 4 = Fow-er, 5 = Fife, 6 = Six, 7 = Seven
- 8 = Ait, 9 = Niner, Decimal = Point
UTC/Zulu Time
All aviation times are reported in UTC (Coordinated Universal Time), also known as Zulu time (designated by "Z"):
| Eastern (EST/EDT) | UTC/Zulu |
|---|---|
| 12:00 PM EST | 1700Z |
| 12:00 PM EDT | 1600Z |
- UTC does not change with daylight saving time
- METARs, TAFs, NOTAMs, and flight plans all use UTC
- Convert local time to UTC for all aviation planning
For the Exam: Know that aviation uses UTC (Zulu) time, the phonetic alphabet, and that 121.5 MHz is the emergency frequency.
The international emergency frequency is:
All aviation times (METARs, TAFs, NOTAMs) are reported in: