Press to Talk, Wait to See: Airport Radio, TETRA and the Network That Comes After It

What radio do airport staff use?

Most UK airports run their ground operations on a private TETRA (Terrestrial Trunked Radio) network. TETRA is a European digital radio standard, first published by ETSI in 1995, and it does a narrow job well: group voice calls set up in a fraction of a second, emergency buttons that override everything else on the channel, handsets with a day and a half of battery and a speaker you can hear over an APU at full chat. Ground handlers, security officers, terminal duty managers, engineering teams and the airport's Rescue and Firefighting Service all tend to sit on talk groups on the same airport network, with a dispatcher or control room console at the centre.

Two other radio systems share the airfield, and it helps to keep them separate. Air traffic control talks to aircraft and to airside vehicles on the manoeuvring area over VHF airband (118 to 137 MHz), and anyone driving on a runway or taxiway needs that radio and a permit to use it. The police, ambulance and local fire services use Airwave, the national emergency services TETRA network that Motorola Solutions operates for the Home Office. An airport's own TETRA network is the third layer, and it is the one an airport owns, renews and pays for.

Why is TETRA radio under pressure at airports?

TETRA is under pressure because the work on the apron has become data work, and TETRA was designed for voice. A single TETRA timeslot carries 7.2 kbit/s; all four together reach 28.8 kbit/s, which is enough for a status message or a location fix and nowhere near enough for a photograph of a damaged hold door, a video call to a remote engineer or a baggage reconciliation app. So the dispatcher sends the job by radio, the handler confirms it by voice, and then the handler opens a separate app on a separate handheld, running over public 4G or terminal Wi-Fi, to log the same job. We have written before about how unreliable that second link is at remote stands and in hangars, in our pieces on the aircraft turnaround and hangar connectivity.

Three other pressures sit on top of that. Firstly, the hardware cycle: many airport TETRA networks were installed in the 2000s and 2010s, base station and handset support has a finite life, and a renewal is a seven-figure decision at a large airport. Secondly, the supply market is thin; in 2023 the Competition and Markets Authority imposed a price cap on Airwave after finding that Motorola was earning profits well above what a competitive market would allow, and airports buying their own TETRA face a small pool of vendors for base stations and handsets. Thirdly, the national picture is unsettled. The Home Office's Emergency Services Network, which is meant to move the blue-light services from Airwave to 4G and 5G, has slipped repeatedly, and Airwave is now expected to run to the end of the decade. Airports that hoped to follow a national lead on broadband push-to-talk have had nothing to follow.

Can 5G push-to-talk replace TETRA radio?

For most airport user groups, yes, provided it runs on a network the airport controls and on the mission-critical standards rather than a consumer push-to-talk app. 3GPP added mission-critical push-to-talk (MCPTT) to the mobile standards in Release 13 in 2016, then mission-critical data and video (MCData and MCVideo) in Release 14. The performance targets in 3GPP TS 22.179 are aimed squarely at the TETRA use case: under 300 ms from pressing the button to being granted the floor, and under 300 ms mouth-to-ear latency, for 95% of calls. The standards cover group calls, late entry to a call already in progress, pre-emption by an emergency call, dispatcher consoles and talk-group management, which are the TETRA features airport control rooms rely on.

What a private 5G network adds is everything TETRA cannot carry. On one handset and one network, a ramp agent can take a push-to-talk call from the dispatcher, photograph a dent on the hold door, stream body-worn camera video to the duty manager and update the turnaround milestones. A security officer at a staff search point can send a photo of a suspect item to the control room while staying on their talk group. On the Aerix network at Bath we run 5G in the n77 band (3.8 to 4.2 GHz) under an Ofcom shared access licence, and the same model applies on an airfield: the airport holds the licence for its own site, sets the priorities, and decides which devices are allowed on.

The reason it must be a private network is priority. A consumer push-to-talk app on a public network competes with every passenger in the terminal for capacity, and on a busy summer morning at a gate with 300 passengers streaming video, that is the wrong place to be competing. On a private network the airport can reserve capacity and give radio traffic a higher quality-of-service class than everything else, so a group call from the stand gets through regardless of what the baggage scanners are uploading.

What should stay on TETRA and VHF airband?

Some things should not move, at least not yet, and we would be wary of any proposal that says otherwise.

VHF airband is outside the scope of any of this. Communication between the tower and aircraft, and between the tower and vehicles on the runway, is set by aviation regulation and the CAA, and nobody is proposing to put it on 5G. Airside vehicles will keep carrying an airband set.

The Rescue and Firefighting Service is the hardest case. TETRA offers direct mode operation (DMO), where two handsets talk to each other with no network at all, and fire crews use it inside buildings and aircraft where coverage is uncertain. 3GPP has a broadband equivalent in off-network MCPTT using device-to-device sidelink, but handset support is limited and few organisations anywhere have run it in anger. The fire service also needs to talk to the local brigade on Airwave during an incident. Until both of those are proven on the airport's own site, the fire service should stay on TETRA, with a gateway to the 5G push-to-talk groups so the control room can still reach everyone.

Battery life and ruggedness are the practical gaps. A TETRA handset will last a long shift on one battery; a 5G handset running push-to-talk, a camera and a scanning app will not, and the airport needs spare batteries or vehicle charging in its plan. Rugged 5G handsets rated IP68 with large push-to-talk buttons and loud speakers do exist, but the airport should test them with gloves on, next to a running engine, before it orders a fleet.

How does an airport move from TETRA to 5G push-to-talk?

In stages, by user group, with the two systems joined in the middle. 3GPP TS 23.283 defines how MCPTT interworks with land mobile radio such as TETRA, and gateways from several suppliers let a talk group span both: the dispatcher speaks once and both TETRA handsets and 5G handsets hear it. That interworking is what makes a phased move safe, because no group has to switch on the same day as the groups it talks to.

A sensible order, in our view, is the following. Start with (i) baggage handling and ground handling, who already carry a second device for data and gain most from having one; then (ii) engineering and facilities, who need photos and remote expert video in hangars and plant rooms; then (iii) terminal operations and customer service staff; and only later (iv) security and (v) the fire service, once coverage has been measured stand by stand and the network has run through a peak summer. Hybrid handsets that carry both TETRA and LTE or 5G, such as the Airbus Tactilon Dabat, give a fallback for groups who want the new data services without giving up TETRA during the transition.

Coverage is where most of the planning effort goes. TETRA at 400 MHz travels a long way and gets into buildings easily; 5G at 3.8 to 4.2 GHz does not, so a private 5G network needs more radio sites than the TETRA network it partly replaces. On an apron that usually means masts on terminal buildings, piers and lighting columns, with indoor cells in baggage halls and hangars. The upside is that the same cells carry the data for turnaround, baggage tracking and electric ground support equipment, so the cost of the radio network is spread across several budgets rather than charged to radio alone.

What should an airport ask before renewing its TETRA contract?

An airport facing a TETRA renewal in the next three to five years should get answers to five questions before it signs a like-for-like replacement:

• Which talk groups carry a second device today? If most of ground handling already carries a smartphone or rugged handheld for apps, a 5G push-to-talk handset can replace two devices with one.
• Where does the current data link fail? Remote stands, cargo sheds, hangars and baggage halls are the usual gaps, and a walk test with a phone will show them in a day.
• Can the renewal be shortened? A three-year extension on the existing TETRA core, rather than a ten-year replacement, keeps the option of a phased move open.
• Does the TETRA vendor offer a broadband gateway? Interworking between TETRA and MCPTT is standardised, and the answer tells you how easy the transition will be.
• What does the fire service need from Airwave and DMO? This sets the timetable for the last and most careful stage of the move.

A smaller regional airport is in a different position from Heathrow or Gatwick. With fewer stands and fewer users, a regional airport can cover its whole airside area from a handful of 5G cells and move most user groups within a single renewal cycle, which is one reason we argued that regional airports suit private 5G. A large hub with tens of thousands of airside staff, several ground handlers and its own TETRA operations team will take longer, and should start with one handler on one pier.

The practical first step costs very little: list the talk groups, count the devices each user carries, and map where the data link drops on a normal shift. If the answer is that half the airside workforce carries two devices and loses one of them at the remote stands, the TETRA renewal is the moment to plan the network that replaces both.