Geostationary satellites detect non GPS 406 signals almost instantly but polar orbiting satellites are required to position fix. The position fix can take up to two hours whilst the satellites move into position. Thus whilst AMSA would be alerted very soon after beacon initiation, it can take time to get a position fix from a non GPS 406.

I'm not sure of AMSA's exact procedures; but a registered 406 distress activation can initiate SAR alert almost immediately. The beacon will send the registered user data and confirmation action can be initiated. E.g. Call a relative to confirm details of voyage etc and begin SAR procedures based on that.

With a GPS equipped 406, position information is transmitted by the beacon immediately with registration data (also later confirmed by doppler fix). Thus AMSA would also get position information when the beacon is activated. This could speed up SAR procedures.

So a GPS equipped 406 does not only improve location accuracy, but can also improve SAR response times.

Commercial aircraft do generally procedurally monitor 121.5, although it is not strictly compulsory. This is also an aircraft distress frequency that an aircraft can issue a mayday on to alert nearby air traffic etc. It is also used (though not quite correctly) for air to air communication. Aircraft will call another aircraft on 121.5 and request they move to a chat frequency. 121.5 in aircraft is usually monitored on a secondary VHF radio as the primary VHF radio is used for Air Traffic Control. The secondary VHF radio is also used for company communication, weather updating etc and so 121.5 is not continually monitored. When a beacon is detected by overflying aircraft, the details are relayed to Air Traffic Control (fade in fade out etc), ATC may then ask other aircraft to monitor and advise for general location identification. I don't know what action ATC then take in regard to this.

I have read that in the US, SAR will not be actioned on a 121.5 distress signal alone. There must be a secondary notification, concerned relative, smoke, fire etc. I am not sure about Australia.

In a Sydney - Gold Coast race some years ago, we saw a rescue helicopter head over toward a distant yacht and then shortly return. I understand they had an accidental/fault with an EPIRB, non monitored VHF etc that ticked enough boxes to initiate a SAR operation.

This one could be good and it's out now on iTunes

Watched "All is Lost" on the flight to LA. Crap realism and not a good movie either. Redford did well in a poor situation.

Always had TV time for the Tiki ( adventure in Paradise )when I was little

HG02 said..

Always had TV time for the Tiki ( adventure in Paradise )when I was little

Always a good show. After visiting the same places the reality is a little different. Wonder how many people were inspired by this show to cruise the Pacific!