Neometrix / Airfield Infrastructure / Voice Communication & Control System / NMX-VCC-10

NMX-VCC-10 · ENGINEERED TO ORDER — POSITIONS · RADIOS · HOTLINES · RECORDING · IP · MIGRATION

The controller must never lose their voice.

Name: Airfield Voice Communication & Control System (VCCS)
Brand: Neometrix

A voice communication and control system is the instrument an air traffic controller plays. Every radio, every hotline and every telephone sits on one touch panel. One touch selects a channel. One press of a pedal talks to the aircraft. And every word is recorded.

So the design starts from failure. Two networks, doubled servers, two power feeds, and a backup radio path that skips the switch entirely. And when an old switch is replaced, both systems stay alive until the last position has moved.

Discuss a voice switch Capability note (PDF)

Fig · 01 — One controller position, drawn: radio tiles, hotlines and intercom on one touch panel, with backup radio keys beside it. Illustrative layout.

The rule

no silent positionno single point of failure

Standard

ED-136 / 137 / 138EUROCAE voice over IP

Integrates

radios + phonesVHF, UHF, hotlines, intercom

Records

every wordevery channel, one clock

Status

engineered to orderquoted class

ISO 9001ISO 14001Clause-by-clause complianceLive-tower migrationIn-house engineering

Overview

Radios and phones are easy. Putting them in one hand is the job.

A tower talks on many channels at once. The voice switch is what makes that possible for one person.

A controller should never have to think about the switch. They think about the traffic. The switch simply has to be there, every second.

What the switch does

A controller may work four radio channels, six hotlines and the intercom in one shift. Each needs a headset, a microphone and a way to talk. Without a switch, that is a desk of separate boxes. With one, it is a single panel.

Touch a radio tile and the headset hears it. Press the pedal and the voice goes out on that channel. Touch a hotline and the fire station answers. Two channels can be joined when traffic needs it. A call can be passed to the next position. The eyes never leave the window.

Why it is built for failure

A silent tower is an emergency. So every part of the switch has a twin. If a network fails, the other carries every call. If a server fails, its partner takes over. If the whole switch fails, separate backup keys still reach the radios.

Why most projects are migrations

Most airfields already have a switch. Many are analogue or early digital, and their spares are running out. The new system is usually IP-based. The real work is moving a working tower from one to the other without a silent second.

This page covers the voice switch only. The airfield data network, the tower building and navigation aids have pages of their own, listed at the foot of this page.

One panelradios, hotlines, phones, intercom

Doublednetworks, servers, gateways, power

Recordedevery channel, one clock

Migrated liveboth switches alive throughout

Architecture

Every path doubled, and one path that skips the switch.

The drawing is read from the controller down to the radios.

FIG · 02IP-BASED VCCS · POSITIONS / NETWORKS A + B / RADIO + TELEPHONE GATEWAYS / LEGACY INTERFACES / RECORDER / LAST-RESORT PATH

Fig · 02 — The architecture. The dashed line on the left matters most: a way to reach the radios that does not depend on anything else in the drawing.

1 · The position

A touch panel, two headset jacks, push-to-talk on the headset, a hand microphone and a foot switch. Loudspeakers for monitoring. A replay key for the last few calls.

2 · The radios

Each channel has a main and a standby radio. Where several receivers hear the same aircraft, the switch picks the clearest signal. Channels can be cross-coupled.

3 · The telephones

Hotlines ring at one touch. Priority calls can break into a busy line. The exchange and old lines join through telephone gateways.

4 · The recorder

Every channel and every position is recorded. Time comes from one master clock. Storage is doubled, and any moment can be found and played back.

5 · The twins

Two networks on separate routes. Paired servers and gateways. Two power feeds into every unit. One failure is a maintenance call, not an incident.

6 · The watchman

Technical supervision shows the state of every unit and link. Alarms go to the maintainer, not the controller. Panel layouts are set here.

Work content

The switch, part by part.

Read the table from the headset outwards.

Part	What it does	What we engineer
Controller position	one panel for every channel	layout, ergonomics, panel roles
Push-to-talk	headset, hand microphone, foot switch	wiring and fail-safe release
Radio gateways	radios onto the voice network	ED-137 radio, main and standby
Best-signal selection	the clearest receiver wins	receiver sites and voting
Telephone gateways	hotlines, exchange, old lines	ED-137 telephone, line plans
Intercom	position to position	groups and priorities
Voice networks A and B	carry every call twice	separate routes, ED-138 design
Servers and gateways	run the switch	paired, with tested takeover
Recorder	keeps every word	ED-137 recording, doubled storage
Master clock	one time for all records	time source and distribution
Supervision	health of every unit and link	alarms, logs, configuration
Backup radio path	reaches the radios if all else fails	independent keys and lines
Power	keeps every unit alive	two no-break feeds per unit
Legacy interfaces	old radios and lines kept working	the bridge for migration

The backup radio row is the one to read twice. Everything else in the table protects the switch. That row protects the controller from the switch itself.

Full specification — expand

System	Airfield voice communication and control system (VCCS): controller positions, radio and telephone integration, intercom, recording, supervision, redundancy and migration from a legacy switch
The One Idea	The controller must never lose their voice. No single failure may silence a position, and the move from an old switch happens with both systems alive
Controller Positions	Touch panel with radio, hotline, telephone and intercom keys; two headset jacks for trainee and instructor; push-to-talk on the headset, a hand microphone and a foot switch; loudspeakers; last-call replay; separate backup radio keys
Radio Integration	Ground-to-air radios, VHF and UHF, main and standby per channel, through ED-137 radio gateways; best-signal selection between receivers; cross-coupling of channels; analogue four-wire interfaces for existing radios
Telephone Integration	Direct-access hotlines, priority and override calls, call transfer and conference, links to the exchange and to legacy lines through ED-137 telephone gateways
Recording	Every channel and every position recorded, timestamped from one master clock, on duplicated storage with search and playback, through the ED-137 recording interface; retention set by the operator’s rules
Redundancy	Two voice networks on separate routes and switches, designed to ED-138; paired servers and gateways with tested takeover; two no-break power feeds per unit; a last-resort radio path independent of the switch
Supervision	State of every unit and link, alarms to the maintainer, logs, role and panel configuration, position split and merge as traffic changes
Standards	EUROCAE ED-136 (operational and technical requirements), ED-137 (interoperability: radio, telephone, recording, supervision), ED-138 (network requirements); ICAO obligations on recording air traffic communications
Migration	Survey → build beside the old → shadow the live channels → train every controller → move positions one at a time, old switch held warm → retire the old switch
Legacy Support	Ageing switches kept serviceable until replacement: processor and interface units, obsolete cards, and bridging to the new system during migration
Sensitive Boundaries	No channel plans, site names, unit names or programme details appear on this page. Those belong in programme documents, exchanged under a tender’s own rules
Scope Boundary	Ours: survey, system design, integration, factory and site testing, migration, training and documentation. Bought in: radios and switch platforms from their makers. The customer’s: the airfield, the operating procedures and the acceptance decision
Status	Work of this class is engineered to order; Neometrix has quoted for voice communication and control system processing hardware and radio-over-IP gateway integration for military users, and no delivered voice communication and control system is claimed.

Migration

Two switches alive, one position at a time.

Nothing is switched that cannot be switched back.

FIG · 03MIGRATION FROM A LEGACY SWITCH · SURVEY / BUILD BESIDE / SHADOW / TRAIN / MOVE / RETIRE

Fig · 03 — The migration. The old switch carries the traffic until the last position has moved, and it can take any position back at once.

New system

An IP-based switch

A new tower or a new unit. Positions, gateways, recorder and supervision designed together, to the EUROCAE standards, and tested in the factory before they reach site.

Migration

Legacy to IP

The common case. The new switch goes in beside the old. Legacy interfaces let both reach the same radios. Positions move one at a time.

Sustainment

Keeping the old one going

Replacement takes years to fund. Until then the old switch must stay healthy. That means processor and interface units, obsolete cards and careful repair.

The panel layout deserves as much care as the network. Controllers work by reflex. A new panel that moves a key moves a habit, so the layout is agreed with the people who will use it.

Where it fits

Anywhere a controller talks to aircraft.

The size changes. The rule about failure does not.

Military airfields

Tower, ground and approach positions, plus hotlines to operations, fire and crash rescue. Both VHF and UHF radios, because military aircraft use both.

Civil and joint-use airports

Where civil and military traffic share a runway, the switch must serve both. Standard interfaces make that a design task, not a custom build.

Approach and area centres

Many positions and many channels. Roles split and merge as traffic rises and falls through the day.

Helicopter bases

Fewer positions, but the same need for hotlines, recording and a backup path to the radios.

Mobile towers

A compact switch for a containerised tower. Same panel, same rules, fewer positions.

Training rooms

A training position with the real panel layout. Controllers learn the new switch before they use it live.

FAQ

Common questions.

Longer answers, for readers who want the reasoning.

Q · 01 What does a VCCS do that radios and telephones alone cannot?

It lets one person use all of them at once without looking down. A tower controller may work several radio channels, a ground frequency, hotlines to operations, fire and crash rescue, the neighbouring approach unit, and an intercom to the next position. Each of those is a separate circuit with its own equipment. Wired as separate boxes, they would cover a desk and demand the controller's eyes. The voice communication and control system brings them to one touch panel. A touch selects what the headset hears. A press of the push-to-talk, on the headset cord, the hand microphone or the foot switch, sends the voice out on the selected radio. Hotlines ring at one touch and are answered at one touch. Two radio channels can be joined, so aircraft on each hear the other. A call can be passed to another position, and positions can be combined at quiet times and split again when traffic builds. Underneath, the switch also does work the controller never sees: choosing the clearest of several receivers, changing to a standby radio when the main one fails, and sending every word to the recorder. That is the difference. Radios and telephones carry voice. The switch turns them into one instrument.

Q · 02 What changes when a voice switch moves to IP?

The wiring and the freedom to mix makers. Older switches were built around their own internal buses and analogue four-wire lines to every radio and telephone. They worked, but every part came from one maker and every extension meant new copper. In an IP-based switch, voice travels as data over a dedicated, duplicated network. EUROCAE wrote three standards for this. ED-136 sets the operational and technical requirements for an IP voice system in air traffic management. ED-137 sets how the parts talk to each other: radios, telephones, recorders and supervision, each with its own part of the standard. ED-138 sets what the network must deliver, so voice arrives on time and without gaps. With ED-137 interfaces, a radio from one maker can work with a switch from another, and a recorder from a third. That makes upgrades smaller: one part can be replaced without replacing all of them. IP does not lower the bar. Voice must still arrive with very little delay, push-to-talk must key the radio at once, and the network must survive a failure without dropping a word. Those are design obligations, met by a separate voice network, two of everything on it, and testing against the standards before anything goes live.

Q · 03 How is the controller's voice protected against failure?

By assuming that every part will fail one day and asking what happens then. The answer must always be: the controller keeps talking. So the voice network is built twice, as network A and network B, on separate cable routes and separate switches; every position, gateway and recorder connects to both. The servers that run the switch are paired, and one takes over from the other without the controller noticing. Each radio channel has a main and a standby radio, and the switch changes over when the main one fails. Every unit takes power from two separate no-break sources, so a supply fault is never a voice fault. Supervision watches all of it and tells the maintainer what has failed, while the controller carries on. Then comes the last layer, which most matters. Each position has backup radio keys that reach the radios by a path independent of the switch. If the whole system were lost at once, the controller could still talk to aircraft on the main channels. All of this is tested, not assumed: links are pulled, servers are stopped and feeds are cut during acceptance, and the test only passes if no call is dropped.

Q · 04 How do you replace a legacy switch without silencing the tower?

By never having only one switch in charge of a position until the new one has proved itself. It starts with a survey: every radio, every line, every key on every panel, and how the controllers actually use them. The new switch is designed from that inventory, so the same channels and hotlines sit in familiar places. It is then installed beside the old one and tested in the factory and on site. Legacy interfaces let both switches reach the same radios. Next comes shadowing: the new switch listens to the live channels and records them, but does not transmit. That proves the radio and line connections on real traffic with no risk. Every controller then trains on a training position with the new panel. Only then do positions move, one at a time, in quiet hours first. Before each move a gate is passed: every channel talks both ways, every hotline rings, the recorder hears it, and failover is tested. Throughout, the old switch is held warm and can take any position back at once. It is retired only after the new switch has carried real traffic through a full cycle of operations, including the busiest hours and the worst weather of the period.

Q · 05 Why does recording matter so much?

Because in aviation the record is part of the safety system. ICAO rules require air traffic services to record their voice communications, both to aircraft and between ground units. When something goes wrong, the recording is the first thing investigators ask for. When nothing goes wrong, it is how training, quality checks and disputes are settled. A recording is only useful if it is complete and if its time is right. So the recorder takes every channel and every position, not a selection. Every recording carries a timestamp from the same master clock that the rest of the system uses, so voice from a radio and voice from a hotline line up to the second. Storage is doubled, so one failed disk loses nothing. Search and playback let a supervisor find a moment by channel, position and time. At the position itself, a short replay lets the controller hear the last call again, which helps when a transmission was clipped or unclear. With ED-137, the recorder can come from a different maker from the switch and still receive every channel in a standard way. The retention period follows the operator's own rules.

Q · 06 What is Neometrix’s record with voice switches?

Work of this class is engineered to order; Neometrix has quoted for voice communication and control system processing hardware and radio-over-IP gateway integration for military users, and no delivered voice communication and control system is claimed. We would rather say that plainly. Those bids are the honest record: processing hardware for an existing voice switch, and the integration of radio networks over IP gateways, each answered clause by clause against the buyer's own specification. Around that record stands adjacent engineering shown elsewhere on this site: airfield ground power and electrical systems, control and instrumentation integration, and test laboratories that prove electronics before they serve. The first contract of this kind would follow the pattern the buyers themselves set: clause-by-clause compliance, factory and site testing, migration around live operations, and training and documentation handed over with the tower still talking. That is the basis we would bid on, and this page claims nothing more.

Q · 07 Can an ageing switch be kept going until it is replaced?

Usually it must be. A replacement programme takes time to plan, fund and install, and the old switch carries the traffic all the while. Its weak points are predictable. Processor units and interface cards go out of production. Spares run short. Knowledge of the system sits with a few people. Sustainment means treating those risks one by one: repairing or re-making processor and interface units, finding or engineering replacements for obsolete cards, and testing every returned unit on a bench before it goes back into a live tower. It also means planning for the migration that will follow. Legacy interfaces chosen today can later connect the same radios and lines to the new switch, so money spent on keeping the old system healthy is not wasted when it is retired. For a buyer, the honest question is not whether to sustain or replace, but how long the old switch must last and what keeps it safe until the day it is switched off.

Q · 08 What does this page leave out, and why?

Two kinds of thing. First, scope that belongs to other pages. The voice switch rides on its own duplicated voice network, but the wider airfield data network is a separate subject. The tower building and its fit-out, the navigation aids, and the whole-airfield upgrade programme each have their own pages too. This page stays with the switch: positions, radio and telephone integration, recording, redundancy and migration. Second, detail that belongs to programmes, not websites. No channel plans, site names, unit names or programme details appear here, and none ever will. Those are exchanged under a tender's own rules. Everything this page does describe is the public engineering of voice switching, by the same names that EUROCAE and ICAO documents use. A supplier's page should show that it understands the work without telling anyone about a particular airfield.

The rest of the airfield, on its own pages.

The switch is one system among several.

↗ The whole airfield

Air Traffic Management Upgrades

Every system around a live runway, renewed without stopping flying.

↗ The power

Ground Power Units

The airfield electrical work behind the switch's two no-break feeds.

↗ The proof

EMI / EMC Test Laboratory

Where electronics are proven quiet and immune before they serve.

Sibling pages cover the airfield data network, control tower modernisation, and navigation aids and airfield systems support. Browse all Neometrix product lines.

Get a quotation

Tell us the positions, the channels,
and the switch you have today.

The projects desk replies within two working days with a clause-by-clause compliance matrix and a budgetary quotation. Write to [email protected] or use the form.

Enquire — voice switch Capability sheet (PDF) +91 7777 876 876

ISO 9001 / 14001 ENGINEERED TO ORDER — AIRFIELD VOICE COMMUNICATION & CONTROL SYSTEM POSITIONS · RADIOS · HOTLINES · RECORDING · TWO NETWORKS · MIGRATED LIVE ENGINEERED IN NOIDA · INDIA