Airborne Reception Airborne Reception Analysis of 406 Analysis of 406

Emergency Locator Emergency Locator BeaconBeacon

Why 406 ELT?Why 406 ELT?

Improved location accuracy and ambiguity resolution

Increased system capacity (i.e. capability to process a greater number of beacons transmitting simultaneously in field of view of satellite)

Increased probability of detection (higher power)

Global coverage Unique identification of each beacon

406 ELT Specifics406 ELT Specifics Enhanced system with improved frequency stability

at a dedicated frequency. Beacons transmit a 5 Watt RF burst of

approximately 0.5 seconds duration every 50 seconds. The carrier is phase-modulated with a digital message. High peak power increases the probability of detection. The low duty cycle provides a multiple-access capability for a large number of beacons simultaneously operating in view of a polar orbiting satellite, and low mean power consumption.

Digitally encoded message, provide information such as the country of beacon registration, identification of the vessel or aircraft in distress, and optionally, position data from onboard navigation equipment.

An auxiliary transmitter (homing transmitter) is usually included in the 406 MHz beacon to enable suitably-equipped SAR forces to home on the distress beacon

Comparison of Standard ELT, ELT Practice Beacons and 406 ELT/EPIRB Beacons

Expected Coverage Range for a 406 ELT at various search altitudes

Expected Coverage Range for the 406 ELT’s (40mw) 121.5 MHz at various search altitudes

Topics to ExploreTopics to Explore

Comparson of 121.5 Comparson of 121.5 ELT vs. 406 ELT/EPIRBELT vs. 406 ELT/EPIRB

121.5 ELT Power

121.775 MHz Practice Beacon Power

406 122.5 Homing Beacon

TX Power

406 Beacon

TX Power

Power 5W 250 MW 40 MW 5WdB 0 -13dB -20dB 0Coverage 1 1/4 1/8 1

Test PlanTest Plan

Simac “Serach-Pro” 406 Practice beacon operating on 406.025 MHz was placed at French Lick Airport (FRH)

Inbound and outbound test flights were were conducted to the north at AGL altitudes of:• 1000’ • 3000’• 5000’• 10,000’

Flights conducted on 3 separate sorties on July 8th & 9th 2009

Aerial Test Platform Aerial Test Platform

Aerial survey was flown in N738CP a Cessna 182T with Garmin G1000 FMS Aircraft• Becker DF 715 receiver used to identify the 406

beacon reception by observing acquisition and loss of data reception

• Garmin VHF Com was used to identify acquisition and loss of the 121.775MHz homing transmitter

Becker 406 Antenna

Becker 121MHz DF Antenna

Becker 121 DF Antenna

Route SurveyedRoute Surveyed

•The location was chosen for its low terrain and geographic separation from the NESA training areas in order to avoid false hits from other training beacons. •Routes were flow using the G1000 GPS and KAP140 Autopilot in OBS NAV mode on bearings of 180 and 360 to and from the north of French Lick (FRH) airport at each altitude previously mentioned.•The same course was flow on to the south of at 1000’ and 3000’ AGL and the results were similar.

406 ELT Detection 406 ELT Detection RangesRanges

406 vs. 121 ELT 406 vs. 121 ELT DetectionDetection

ObservationsObservations

Better reception going away from the 406MHz beacon than going toward• Suspect that this has to do with the rearward

placement of the 406 antenna Better reception as altitude increases

but above 5000’ AGL the benefit begins to diminish

Up to 10,000’ AGL can receive 406MHz as far as 50NM from the beacon

Up to 10,000’ AGL can receive 121MHz homing signal as far as 22NM from the beacon

Tangent reception from the side on the Becker antenna was virtually identical to results of ahead or behind

ConclusionsConclusions

Aircrew should approach search area above 5000’AGL initially

Once the 406 signal has been acquired, turn to the suggested heading and descend while approaching the area

As ambiguity decreases make minor course corrections and continue decent.

Monitor 121.5 (or 121.775 MHz) on the Com radio

Final DF using 121.5 (or .775) is most effective at close range.

Limitations and Limitations and ShortcomingsShortcomings

Limited Dataset• Limited to one Aircraft and radio system• Did not get L-Tronics data

Battery life of ELT Practice Beacon unknown• 2004 Battery

Would like to compare 406 and 121.775 beacon from the same location simultaneously