Locator Beacon

//Locator Beacon
Locator Beacon 2015-06-24T20:46:31+00:00

The club has a locator beacon available for club members to take on tramping trips. Club members may also use it for private trips although scheduled club trips have first priority.

If you wish to borrow the Beacon contact Tom Wood at least a week before the start of the trip to arrange collection of the unit from him.   ph: 815 5795 or email: trwood@xtra.co.nz

Please read the following information before your trip.

Make sure that everyone in the party knows where the PLB is and know how it operates. (There are instructions on it) A lost few minutes activating it may be critical.

Know how to deactivate it.  There are a number of reasons for this.

Keep the antenna pointed upwards. This helps send a strong signal

Once activated do not touch the aerial. The PLB sends a signal every 58 seconds strong enough to travel 100,000 miles. This energy source can give severe radiation burns.

Above all remember that the PLB is only to be used in the case of an emergency when other means of contacting rescue services such as by cell phone isn’t available. We would be very pleased if it is never activated. It is only the “ambulance at the bottom of the cliff” and doesn’t replace competent route finding, risk analysis and thorough planning on a tramping trip.

Ralph Fox of our club was the first tramper in New Zealand to be rescued with the aid of a 406 beacon. Because of the promptness of his rescue and many “warm fuzzy stories” since it may appear all that is necessary is to turn on the beacon and then listen out for the imminent “whoop, whoop” of the arriving rescue chopper. While the 406 system greatly improves the chances of a speedy rescue by knowing a few of the features of the system may improve the promptness of your rescue.

When activated the beacon sends a signal that is received by one of two types of satellites and is passed usually within 8 minutes to the Rescue Coordination Centre in Wellington – one of 14 around the world. The distress signal is received in the first instance by one of four Geo-stationary satellites that are in orbits above the equator and approximately 40,000 miles above the earth’s surface.  Their orbit takes exactly the same time as the earth’s rotation giving the effect of being in the same place above us all the time. Despite the height above the earth of the satellite the signal may not be received if it is blocked by a landmass such as a mountain to the north of the beacon emitting the signal. This can be critical when the distressed party is in a valley or riverbed remembering that most of New Zealand’s rivers run east or west.

When activating a PLB give regard to the northern horizon from your location. It may require the PLB to be taken over a ridge or moved east or west to obtain a lower horizon to the north.

The distress signal emits a code that allows the Rescue Centre to identify the beacon as belonging to the West Auckland District Tramping Club and they will immediately phone the contacts listed above to learn the number in the party, where they might be and of any significant medical conditions of party members. This will enable them to tailor the search accordingly.

There can also be a period of time when the Rescue Centre may have two different locations for the source of the signal some hundreds of kilometres apart due to the Geo-stationary satellites being “stationary” and can only ascertain the correct one via the contacts.

The second chance to pick up the distress signal is by Low Earth Orbiting (LEO) satellites.  These 5 satellites are about 900 kilometres above the earth’s surface and have orbits that pass over the poles travelling at 7 kilometres a second so making a revolution every 105 minutes. The advantage of the moving LEO satellites is that they at some stage of the orbit can access line of sight into valleys and behind mountains that may have blocked the distress signal to the GEO satellites. They can also more accurately locate the source of the distress beacon by the “Doppler” effect.

Until 2014 there aren’t enough LEO satellites to give continuous cover, the gap varying between 7 minutes and 2 hours. At present in New Zealand the biggest gap occurs between 12pm and 2pm – have a long lunch before trying a tricky climb or crossing!