# TMZ and RMZ Explained: What VFR Pilots Must Do

> A radio mandatory zone (RMZ) is airspace of defined dimensions in which carrying and operating radio equipment is mandatory; a transponder mandatory zone (TMZ) is airspace of defined dimensions in which carrying and operating a pressure-altitude reporting transponder is mandatory.

NOTAMbriefing.com, https://notambriefing.com/guides/tmz-and-rmz. Last updated 2026-09-23.

## Where RMZ and TMZ come from

Both zones are defined in the Standardised European Rules of the Air (SERA, Regulation (EU) No 923/2012), and their requirements are in SERA.6005. A competent authority designates them on top of the airspace class; they add equipment and communication rules but do not change the class.

They are used where the class alone would let aircraft fly unknown to air traffic services, typically an RMZ in class E, F or G, for example around an uncontrolled aerodrome with instrument approaches, and a TMZ where controllers and collision-avoidance systems need to see every aircraft. SERA requires both to be published in the AIP.

## RMZ: what you must do

SERA.6005(a) applies to VFR flights in parts of class E, F or G airspace designated as an RMZ, and to IFR flights in parts of class F or G airspace designated as an RMZ:

- **Before entering**, make an initial call on the appropriate frequency containing the station you are calling, your call sign, aircraft type, position, level, the intentions of the flight, and any other information the competent authority prescribes.
- **Inside**, keep a continuous air-ground voice listening watch and establish two-way communication as necessary.
- **Without a working radio**, you may enter only in compliance with the alternative provisions the air navigation service provider has prescribed for that RMZ.

An RMZ does not turn the airspace into controlled airspace. In a class E, F or G RMZ, a VFR flight still needs no clearance: the zone requires you to talk, not to be cleared.

## TMZ: what you must do

SERA.6005(b) applies to all flights in airspace designated as a TMZ:

- **Carry and operate** an SSR transponder capable of operating in Modes A and C, or in Mode S. A transponder without altitude reporting (Mode A only) does not meet the requirement.
- **Switch it on** with altitude reporting before you enter, and set the code assigned by ATS or, if none is assigned, the code the AIP prescribes.
- **Without a suitable transponder**, entry depends on the alternative provisions the air navigation service provider has prescribed for that TMZ.

A TMZ is not tied to a particular class, and it can be combined with an RMZ; the AIP and charts then show an RMZ/TMZ.

## RMZ and TMZ side by side

The two zones compared:

Table: Radio mandatory zone and transponder mandatory zone compared (SERA.6005)
|  | RMZ | TMZ |
| --- | --- | --- |
| Requirement | Carry and operate radio; initial call before entry; continuous listening watch | Carry and operate a Mode A and C or Mode S transponder |
| Applies to | VFR in designated parts of class E, F or G; IFR in designated parts of class F or G | All flights in the designated airspace |
| Clearance | Not required by the RMZ itself | Not required by the TMZ itself |
| Exceptions | Alternative provisions prescribed by the air navigation service provider | Alternative provisions prescribed by the air navigation service provider |
| Source | SERA.6005(a) | SERA.6005(b) |

## Worked example: an illustrative RMZ transit

Illustrative scenario: a VFR pilot in a Cessna 172 plans to cross an RMZ in class G around an uncontrolled aerodrome with instrument approaches. The station, call sign and places below are invented.

```text
EXAMPLEFIELD INFORMATION, D-EXYZ,
CESSNA 172, 5 NM NORTH OF EXAMPLEFIELD,
2500 FT QNH 1013,
VFR TO WESTTOWN, TRANSITING THE RMZ NORTH TO SOUTH
```

- The call contains every element SERA.6005(a)(2) lists: the station called, call sign, aircraft type, position, level and intentions.
- After the call, the pilot stays on the frequency until leaving the RMZ. There is no clearance to wait for, but instructions or traffic information may follow.
- If the route also enters a TMZ, the transponder must already be operating with altitude reporting.

## Before your next flight

Plan RMZs and TMZs like any other airspace boundary:

- Mark every RMZ and TMZ on your route on the [live map](https://notambriefing.com/) or chart, with the frequency to call.
- Check the class underneath; see [airspace classes A–G in Europe](https://notambriefing.com/guides/airspace-classes-europe).
- Check NOTAMs for changes to the zones or their hours; see [how to read a NOTAM](https://notambriefing.com/guides/how-to-read-a-notam).
- Look up any term in the [NOTAM and airspace glossary](https://notambriefing.com/glossary).

## Common pilot questions

### Can I fly through an RMZ without a radio?

Only if you comply with the alternative provisions the air navigation service provider has prescribed for that RMZ. Otherwise SERA.6005 requires a continuous listening watch and an initial call before entry.

### Is a Mode A transponder enough for a TMZ?

No. SERA.6005 requires a transponder capable of operating in Modes A and C or in Mode S, so the aircraft reports its pressure altitude. Without one, entry depends on the alternative provisions for that TMZ.

### Do I need a clearance to enter an RMZ?

No, not because of the RMZ. For VFR flights an RMZ is designated in class E, F or G airspace, where VFR flights need no clearance. The RMZ requires an initial call and a listening watch, not a clearance.

### Where are RMZs and TMZs published?

SERA requires RMZs and TMZs to be promulgated in the aeronautical information publications, so the national AIP and the aeronautical charts show their limits, hours and frequencies. NOTAMs announce temporary changes.

## Sources

- [Commission Implementing Regulation (EU) No 923/2012, Standardised European Rules of the Air (SERA)](https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:32012R0923), European Union (EUR-Lex)
- [SERA.6005 Requirements for communications and SSR transponder (UK CAA regulatory library)](https://regulatorylibrary.caa.co.uk/923-2012/Content/Regs/01580_SERA6005_Requirements_for_communications_and_SSR_transponder.htm), UK Civil Aviation Authority