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Aviation Radio Systems
Aviation Radio Systems covers the equipment a rig or vessel uses to talk to and guide helicopters: aeronautical VHF transceivers and control consoles, non-directional beacons (NDBs) with their antenna tuning units, antennas and the weather sensors behind the reports passed to pilots. A used set brings no licence, so plan for frequency and approval at the new location.
How an offshore aeronautical station works
The helideck radio operator talks to helicopter crews on aeronautical VHF between 118 and 137 MHz, using amplitude modulation (AM) voice. Before each landing the operator reports wind, pressure, temperature, visibility and cloud. On a floating unit the report also includes deck motion from the helideck monitoring system. Aeronautical VHF is a separate band from marine VHF, so a marine set on the bridge cannot replace it.
An NDB transmits a low or medium frequency signal that the helicopter's direction finder homes on. CAP 437 does not make an NDB mandatory, and many helicopter contractors now fly offshore approaches on satellite navigation and airborne radar instead.
Configurations
- Single VHF transceiver with a desk control unit
- Dual or multi-channel stations that monitor traffic and logistics frequencies at once
- Portable handheld aeronautical radios for helideck crews
- NDB transmitters with an antenna tuning unit and vertical or T antenna
- Automated weather systems with anemometers, barometer, visibility sensor and ceilometer
Key specifications
| Parameter | Why it matters | Typical classes or units |
|---|---|---|
| Frequency band | Must cover the assigned channels | 118 to 137 MHz, 8.33 or 25 kHz spacing |
| Channels worked at once | Traffic and logistics may be needed together | Number of simultaneous channels |
| Transmitter power | Sets range to approaching aircraft | Watts |
| NDB output and range | Must suit the approach design | Watts, nautical miles |
| Power supply | Radio must survive a main power loss | DC volts, UPS minutes |
| Ex rating | For antennas and sensors near hazardous zones | ATEX or IECEx zone |
Standards and licensing
CAP 437 sets the communication and meteorological requirements for UK helidecks and says the radio should run from an uninterruptible supply. In UK waters, fixed installations and UK-registered mobile units need a Wireless Telegraphy Act licence from Ofcom and CAA approval for the aeronautical station. Each person who transmits needs a CAA offshore radio operator certificate of competence. Other countries apply their own aviation and spectrum rules, so check with the local authority.
Failure modes and inspection
- Antenna feeders and connectors corrode and take on water. Measure the voltage standing wave ratio (VSWR).
- Transmitter output falls and receiver sensitivity drops with age. Bench test both against the manufacturer's figures.
- Older sets may only tune 25 kHz channels and cannot work 8.33 kHz spacing.
- NDB antenna tuning units and earth mats are matched to one site, and their settings rarely carry over.
- Weather sensors drift. Check calibration certificates for the anemometers and barometer.
- Spare boards for discontinued models are hard to find. Check the manufacturer's support status.
Documentation
- Type approval or certificate of conformity for the radio
- Bench test report with power output and sensitivity
- Calibration certificates for the weather sensors
- Wiring diagrams, antenna drawings and site survey for any NDB
- Manuals and the software version of any console
Integration and compatibility
The station needs a UPS, antenna positions clear of the derrick and cranes, and a feed from the helideck monitoring system on floating units. Weather sensors must sit where the rig structure does not distort the wind reading. Marine band equipment belongs in VHF and UHF radio systems, and meteorological sensors in weather monitoring systems.
Refurbishment and recertification
A used VHF set makes a sound spare if the model is still supported and covers 8.33 kHz spacing where your airspace requires it. Have the set bench tested and aligned before installation. An NDB needs a new site survey, tuning and flight check at the new location. Ask your helicopter contractor whether they want an NDB at all before you buy one.
FAQ
Frequently asked questions
Does an offshore helideck need an NDB?
No, CAP 437 does not make a non-directional beacon mandatory on fixed or mobile installations. Whether to fit one is agreed with your helicopter contractor, and many now fly offshore approaches on satellite navigation and airborne radar. Where an NDB is fitted in UK waters it needs a licence and CAA approval.
Do I need a licence to operate a used helideck radio?
Yes, the licence belongs to the station, not the radio. In UK waters a fixed installation or UK-registered mobile unit needs a Wireless Telegraphy Act licence from Ofcom and CAA approval for aeronautical radio. A used set therefore needs a new application, and each operator who transmits needs a CAA certificate of competence.
What frequency band does a helideck radio use?
A helideck radio works on aeronautical VHF between 118 and 137 MHz, using AM voice. This is separate from marine VHF, so a marine band radio cannot replace it. Check that a used set tunes the 8.33 kHz channel spacing if the assigned frequency or local airspace requires it.
What should I test on a used aeronautical VHF radio?
Test a used aeronautical VHF radio for transmitter power, frequency accuracy, modulation and receiver sensitivity on a radio test set. Measure the antenna system's VSWR once installed. Also confirm the manufacturer still supports the model, because spare boards for discontinued sets are hard to source.
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