Emergency Communications Frequency Planning: Where to Meet When It Matters
Why frequency planning is the first lesson
In normal operating, frequency is disposable — this spot is crowded, move to the next. Disaster does not allow that.
Three reasons. The person who needs help and the person who can help may never have met; the only thing that can bring them together is a frequency agreed in advance. Second, “let’s try another channel” in the middle of chaos usually means lost contact — both sides move to different places and never find each other again. Third, repeaters and the power grid can both fail, so you need a degradation path for when the infrastructure underneath you disappears.
The core work of emergency communications is therefore to fix the frequencies and procedures in advance, write them on a card, and tape it to the equipment.
Design the layers by infrastructure availability
A complete plan is layered by what infrastructure still works:
- Layer 1: local repeater available — use the repeater’s primary output
- Layer 2: repeater failed — drop to simplex (direct, radio to radio)
- Layer 3: all local VHF/UHF gone — move to HF: NVIS for short range, skywave for distance
- Layer 4: fully off-grid, no HF gateway either — digital store-and-forward, or plain human relay
Each layer has to be thought through beforehand, because the moment you need to degrade is usually the moment you are least able to think.
Simplex: the frequencies worth memorizing
Two simplex frequencies appear in almost every national and regional emergency scheme:
- 2 meters — 146.520 MHz, the national FM simplex calling frequency in ITU Region 2 (the Americas). When repeaters are gone, this is the most commonly designated fallback
- 70 cm — 446.000 MHz, which serves the same role across much of ITU Region 1 (Europe)
Around the primary, plans usually list a few adjacent working frequencies (for example 146.460, 146.475 and 146.490 MHz on 2 m) so traffic can spread out when the calling channel congests.
These are international conventions, not legal assignments everywhere. In China, the frequency table published by your provincial radio management authority, or the one agreed with your local emergency group, always outranks any generic advice. If a local emergency frequency table exists publicly, that table wins.
Repeaters and Winlink gateways
Besides voice channels, the card should carry data frequencies. Published regional tables typically list, in addition to repeater primaries and the national simplex channels:
- Winlink gateway frequencies (for example 145.610 MHz on 2 m), for moving structured traffic when voice is inconvenient
- Backup receivers on repeaters, and cross-region linking repeaters
The value of these entries shows up when voice nets are saturated: moving form-type content onto a data path takes real load off the voice network.
HF: which band for which distance
HF planning cannot stop at “which frequency” — it has to say “which band for which distance”. A widely cited mapping:
- County level / short range (under 200 km): 60 m NVIS or 40 m NVIS
- Provincial / medium range (200 to 800 km): 40 m
- Inter-provincial (500 to 1500 km): 30 m or 20 m
- Cross-region / nationwide (over 1500 km): 20 m
NVIS — near vertical incidence skywave — means high-angle propagation aimed almost straight up, precisely to cover short distances. Normal DX work chases low angles; emergency work very often needs the opposite, because the typical requirement is “get this message to a command post a few hundred kilometers away.”
Public emergency tables show the same layering in practice: provincial nets on 40 m by day and 80 m at night, plus fixed watch frequencies on 40 m and 20 m.
Geomagnetic storms are the variable here. NOAA’s Space Weather Prediction Center grades storms on a G scale: at G1 to G2, HF propagation fades mainly at higher latitudes; at G3 and above, HF radio can become intermittent across much wider areas. Operationally, when a strong storm is in progress, I drop short-range NVIS traffic to 60 m — more robust than 40 m — and keep a VHF/UHF fallback for genuinely local coordination inside about 50 km.
Beyond voice: digital modes worth a line on the card
- Olivia — extremely robust, decodes in conditions where nothing else does; many emergency groups list it as a disaster mode
- JS8Call — free-text messaging built on the FT8 protocol, with store-and-forward so messages can be relayed without a repeater
- Winlink — radio email, supports attachments and ICS forms, and supports pure point-to-point operation with no internet at all
Their shared value: when voice is unintelligible, they still deliver exact text. The most common failure in emergency traffic is a number or address copied by ear — digital modes route around that entirely.
Operating principles matter more than frequencies
Frequency planning is only the skeleton. What keeps order on the air is discipline:
- Listen first. Before transmitting, monitor for a few minutes — is there an active net, who is in control
- Use minimum power. Excess power can key up multiple repeaters at once — interference and wasted battery
- Simplex when you can; leave repeaters for the links that need them
- Leave gaps between exchanges. Count two or three seconds after the other station finishes before keying, so urgent traffic can break in
- Relay only verified messages. Do not create or spread rumor. The hardest thing to control in a disaster is not the signal, it is the information
- Do not “broadcast”. Even if the public is listening, our transmissions are not aimed at them — that is the job of the command structure
- Prioritize messages: emergency, priority, welfare, routine — in that order, not by who has the strongest signal
The one thing you can do today
You do not need to wait for a drill. Take a sheet of paper and write down:
- Your local repeater’s primary, backup receiver, and CTCSS tone
- The 2 m and 70 cm simplex fallbacks
- The Winlink gateway frequency for your area or the nearest one
- Emergency net frequencies on 40 m, 80 m and 20 m
- Your local radio authority’s or association’s emergency contact
Then laminate it, or tape it inside the lid of the equipment box. On the day you actually need it, you will not want to be recalling any of these numbers from memory.
References
- IARU, Emergency Communications (iaru.org) — regional emergency coordinators and the IARU Emergency Telecommunications Guide
- Amateur Radio Wiki, Emergency Frequencies (compiled from the RSGB band plan) — IARU Region 1 emergency centres of activity at 3.760 and 7.110 MHz; global centres at 14.300, 18.160 and 21.360 MHz
- ARRL, ARES Field Resources Manual (rev. 2019) — operating principles and message priority
- NOAA Space Weather Prediction Center, NOAA Space Weather Scales (accessed October 2026) — G-scale geomagnetic storm effects on HF
- Ministry of Industry and Information Technology (China), Measures for the Administration of Amateur Radio Stations, Order No. 67 (2024)
- Winlink Global Radio Email (winlink.org)