Channel 16 blocked by careless radio operators

by Nancy Knudsen on 24 Oct 2010 Private yachts are putting lives at risk by accidentally blocking the airwaves, the coastguard in Britain has warned, and Marine Rescue NSW agrees, with some good advice.

In the British situation, rescue personnel have been unable to find vessels in distress because pleasure boats have left their radios transmitting, blocking the emergency frequency.

Twice in recent weeks the problem has been so severe that a lifeboat and helicopter had to be dispatched to locate the source of the signals, because of fears mayday calls could be missed.

On Saturday a barely audible mayday signal was received while a helicopter was hunting for the source of the radio interference, and the aircraft had to be diverted for an hour-long search involving two other boats.

By the time help arrived the single injured crewman aboard the boat had become unconscious, and coastguard watch officer Audrey Pedersen said the time wasted in finding him could have proved fatal.

'If we miss a mayday call it could have very serious consequences indeed,' she said. 'On this occasion all we could hear was the man going in and out of consciousness, but there was too much noise to make out anything else.

'Most of the time when this happens it's short-lived and only an irritation, but when it goes on for hours it puts lives in danger because we could easily miss a mayday signal.

'If members of the public are going to take private boats out they need to pay extra special attention to their microphones to make sure they are not left broadcasting permanently.'

When I asked Ian Brown, Operations Communications Officer, Marine Rescue NSW about the Australian situation, he had this to say:

As well as first hand experiences of hearing channel 16 left open by an unidentified vessel, I am also advised that Marine Rescue NSW (MRNSW) at Terrey Hills can certainly report that this occurs at odd intervals and for varying lengths of time. Without doubt, leaving Channel 16 open could very possibly lead to the issues referred to in the UK report.

We also experience VHF Marine repeaters being held open - this probably occurs, on average, on a monthly basis and due to repeater propagation coverage, causes wide area communications issues.

Causes of this could be:

1. Using the radio
- Changing to a working channel, completing the call, changing back to channel 16, and then not securely replacing the microphone on the microphone clip.

- Microphones are sometimes left on seats, or dashboards, where the push to talk button is inadvertently depressed.

- If the push to talk switch is 'sticky', incorrect handling of the microphone will greatly increase the risk of inadvertent transmission.

2. Use of lesser quality radios
- Lesser quality radios tend to have poor quality microphones and push to talk switches. We know from experience that these radios and microphones do, and will continue to inadvertently cause both intermittent and unwanted radio transmission.
3. Carelessness/lack of consideration for other users
- Many fishermen leave their radios on repeater channels so that they can chat regularly to their mates. Poor quality radios, poor radio operating practices, and a complete lack of attention to the maintenance of their radio equipment leads to issues such as holding open of channels. Most radio users do not regularly check (or do not know how to check) to see if their radio is able to receive correctly – simple checks such as squelch setting, power light on, possible transmit light on, and noticing that nothing has been heard on the radio for a while. If the radio has been set to dual watch, or scan - is it still scanning properly? A held up channel would be immediately noticed if regular radio vigilance was maintained.

The good quality and some mid range VHF Marine radios available in Australia are fitted with transmit time-out timers to address the open channel issue. These are typically set to automatically turn the transmitter off after it has been transmitting for a pre set time - five minutes in some radios. Timers are also fitted to MRNSW repeaters - these typically operate to turn off the transmitter after 3 minutes. Transmit time-out timers reset once the transmitter is de activated - ie the operator releases the push to talk switch. Transmit timers do not help when the radio is transmitting intermittently, as the timer is continually reset.

There are four key points or lessons for marine radio users.

The most important lesson to pass on is that VHF radio users MUST be properly qualified - ie be trained and licenced - to operate their radio. Many Marine Rescue NSW units offer courses for MROVCP and MROCP.

The second most important lesson to pass on is that when out on the water, radio users MUST regularly check their radios and MOST particularly, after radio use, must return the microphone to its clip and check that the radio is receiving properly. Users MUST monitor VHF channel 16 and if they desire, dual scan or otherwise scan other channels.

Apparent lack of radio traffic must prompt the user to make sure the radio is operating - ie back off the squelch, reset the volume and then reset squelch until radio is quiet, and as a quick receiver check. A check to see if a repeater 'tail' is received will confirm radio operation on a repeater.

The third most important message is that radio users MUST have their radio regularly checked by a qualified person to ensure that it is in proper working order Just as smart skippers have an annual mechanical check of their vessel, a radio check should be included.

This MUST include a thorough check of the microphone push-to-talk switch, a check to make sure that a properly fitted microphone mounting clip has been installed and that the microphone is not mounted in an unsuitable location in the vessel. The microphone wiring must be checked to ensure that it is not intermittent or faulty.

The fourth message concerns the maintenance status and age of the radio. High quality commercial two way radios are regarded by industry to have a reliable working life span of about 10 years. Radios and radio installations of commercial two way radios in use by commercial and emergency services are usually checked on an annual basis to verify that they are fit for operational service.

By way of comparison, many marine radios are of recreational usage quality and have an operational life span of 5 or so years - this is providing that regular maintenance and installation checks are carried out. How many recreational vessel owners can say that their radios and radio installations have been regularly checked and maintained by properly qualified personnel, and that radios are of a reasonable age??



I hope these comments will assist

Regards

Ian Brown
Operations Communications Officer
Marine Rescue NSW