MART Vol. II MO/MP - NESA - Civil Air Patrol

activation (e.g., removal/installation), malfunctions, or Monsieur Murphy. Also,non-ELT sources can transmit on 121.5 or 243 MHz; examples are computers,broadcast stations, and even pizza ovens.Approximately 97% of all received 121.5 MHz ELT signals turn out to be falsealarms. For 121.5 MHz ELTs only 1 in 1000 signals is an actual emergency!False alarms caused problems because SARSAT could only monitor 10 ELTsignals at a time and because they blocked the emergency frequencies (thusblocking a real emergency signal). However, you must always treat an ELT signalas an emergency because you can't know whether the signal is real or false.Additionally, ELT missions keep your skills sharp.7.1.2 SARSAT/COSPASIn a cooperative effort among several nations, search and rescue-dedicatedsatellites (SARSAT and COSPAS) orbit the earth and alert to 406 MHz ELTtransmissions. In the event the ELT is activated (such as during a crash) ittransmits the standard swept tone on 121.5 and 243.0 MHz at 100 milli-watts.Additionally, every 50 seconds for 520 milliseconds the 406.025 MHz 5-watttransmitter turns on; during that time an encoded digital message is sent to theNOAA-SARSAT satellite (part of the COSPAS-SARSAT satellite system). Afteractivation the 406.025 MHz transmitter will operate for 24 hours and then shutsdown automatically; the 121.5/243.0 MHz transmitter will continue to operate untilthe unit has exhausted the battery power (at least 72 hours).The information contained in the ELT message is:• Serial Number of the Transmitter or Aircraft ID• Country Code• I.D. Code• Position Coordinates (Lat/Long), if coupled to the aircraft’s GPS unit406 MHz ELTs must be registered with the United States the NationalOceanic and Atmospheric Administration (NOAA). This identification code helpsthe Air Force Rescue Coordination Center (AFRCC) determine whether anemergency actually has occurred. The code permits accessing a registrationdatabase that contains the:• Owner's Name• Owner's Address• Owner's Telephone Number• Aircraft Type• Aircraft Registration Number• Alternate ContactFor 406 MHz ELTs without GPS position data it is necessary for the polarorbiting satellites to pass overhead, using Doppler Shift technology to determineapproximate position; this results in position accuracy of 1-3 nm. If the ELT iscoupled to the aircraft’s GPS unit, the position data is also transmitted andposition accuracy improves to within 100 yards. [Note: in a worst-case scenario,there could be a 3-4 hour wait for a polar orbiting satellite to pass overhead.]AFRCC uses the registration data to inquire about the whereabouts of theaircraft (e.g., contacts know the owner if flying or the FAA has a Flight Plan onfile). If AFRCC determines the aircraft is really missing, they will immediatelylaunch a search.117