Some Insite To Distress Beacons
Mademan112,
I share your concerns with passion and I am really pleased that members of this forum went out of their way to act in the most diligent manner to give this incident the rightful attention.
121.5Mhz beacons are going to be phased out, from memory, by February 2009. As we all know, they transmit analogue data which is no use when the distress beacon and the Local User Terminal (LUT) are not in the satellite’s footprint. This increases the time of detection as you will now have to wait for a satellite whose footprint will be appropriate. So, if the next one comes over without the desired footprint, no show again. Each low earth orbiting (LEO – 800~1000km above the earth surface) satellite takes about 90 minutes to complete one polar orbit, while the geo-stationary (GEO) ones remains at 36000km above the Equator and these, owing to their stationary nature, does not pick up 121.5MHz distress signals. As the whole calculation is Doppler based, the computation would require a minimum of two satellite passes to resolve the actual position. Each satellite pass gives you two possible positions. The ground station requires a LEO-LUT (low earth orbiting satellite local user terminal) to finalise the whole computation. Now this is where we Pilots can get a little technical and do what we can to help! If you have a spare radio, keep one tuned permanently to 121.5Mhz. When you fly over an area where a beacon is active, you will know from the very distinct sound you will get on your head set (a bit similar to that from the first man made satellite in space - SPUTNIK). Note the position when you pick up the signal and note the position when it fades off. Pass the info with your altitude to the Air Traffic control, which I think should pass it onto the ground fellows at the Search and Rescue Centre. With so many reports we can come up with several circles of position and narrow down the search area. See how we have turned our aircrafts into satellites! It should not be difficult to make this a recommendation or encourage the Airline Operators to have it as part of their operating procedure. After all, we are all watching each others back! Even the doctor at some point in life may require a doctor too! But we have to educate the Air Traffic Controllers too, so they know the importance of the information being passed on to them.
406mHz distress beacons have the ability to be resolved by one satellite pass. Even better if the beacon is GPS equipped (known as Location Protocol Equipped Beacons), as a precise location can be obtained via the geo-satellites. However, for this to be possible, the ground station monitoring distress beacon signals must have a GEO-LUT (geo-stationary satellite local user terminal). 406MHz beacons come with a hexadecimal code know as the HEX ID. If registered with a Search and Rescue organisation, the moment a signal is picked up, it transmits this code and we can immediately tell who is in distress. These distress beacons don’t have to be in the same footprint as the Local User Terminal like their 121.5MHz counterparts. If the distress beacon is not in view with the LUT at the same time, the satellite stores the data and transmits that data the moment it comes in view of another LUT. It is the responsibility of the guys working in that LUT to pass on that data via their NODAL MCC to the appropriate Search and Rescue Coordination Centre. One other advantage of the 406MHz distress beacon is they all have a low-powered 121.5MHz component, for homing purposes.
Here on my computer screen, I can see the symbol of a LUT situated right in Abuja. I have no clue on what goes on there, it may very well be in its infancy stages. But there is one thing I know for sure! And that is on quite a number of occasions, Nigeria sends one of the highest amount of delegates to the COSPAS SARSAT meetings overseas! Second only to the number of delegates sent by the United States! What they go out to do and what they take back remains another very interesting lecture I would really love to attend.
Best wishes