Presentation on theme: "Authored by Scott E. Lanis 28-Aug-1998 Modified by Lt Colonel Fred Blundell TX-129 Fort Worth Senior Squadron For Local Training Rev 5.0 02-Feb-2014."— Presentation transcript:
Authored by Scott E. Lanis 28-Aug-1998 Modified by Lt Colonel Fred Blundell TX-129 Fort Worth Senior Squadron For Local Training Rev Feb-2014
OBJECTIVES By the end of this course, you should: Know what an ELT is, and how it can be activated Understand why an ELT signal is an emergency Describe how CAP is called out on an electronic search Be familiar with these fundamentals: Plotting a SARSAT hit on a map (latitude/longitude) Direction finding - Little L-Per Operation Triangulation Body shielding Aircraft coordination/LORAN/GPS operations Ground Vehicle Operations
Is an Aircraft Missing? How would we know? Radio distress call Monitored aircraft drops from RADAR Overdue Flight Plan Report from friends/relatives ELT Signal (maybe!)
How does CAP Search for Missing Aircraft? Purely Visual Searches Very Difficult: often few clues Air - most effective to cover ground Ground Electronic Searches - Quick (24 hrs) Air - best reception and range Ground - autonomous search is slower and more difficult Advanced Technology Few of these resources available directly to CAP Synthetic Aperture Radar (SAR), Thermal/Infrared Imagery, Other Remote Sensing (satellites/reconnaissance aircraft)
What Will A Crashed Airplane Look Like?
Air to Ground Coordination The most effective way to search The only way CAP stays in the SAR business The plan: CAP aircraft locates crash (visual / electronic) Coordinates to bring ground team on scene Radio (transmit the Lat-Longs from LORAN/GPS!) Radio Out Lat-Long (LORAN/GPS) Ground Team effects rescue
Aircraft Limitations Weather Cant pinpoint signal Row of hangers
Ground Search Types for Missing Aircraft Ramp Search Ensure the missing aircraft has not landed safely Can be conducted by both air and ground crews Bastard Search Ensure the missing person isnt in a favorite hangout You bastard!
How does a search start? There is the possibility of a missing aircraft Radio distress call, aircraft drops from RADAR, overdue flight plan, report from friends/relatives, ELT Signal AFRCC performs a telephone search Airport managers, towers, etc. Missing Aircraft Confirmed! AFRCC activates the appropriate CAP wing
What if only an ELT signal is received? AFRCC Telephone Search Airports: Do you hear it too? Likely false alarm at this point; signal silenced by crews on airport CAP called sooner if after hours No one else answers the phone! Is there another indicator of a missing aircraft? If not, AFRCC will wait to see if the signal terminates Tests Inadvertent actuations terminated
What is an ELT anyway? Emergency Locator Transmitter Its an automatic radio beacon! 3 Frequencies of Operation MHz (VHF) AND 243 MHz (UHF) (Military Guard) MHz (new) Most aircraft have ELTs installed
General Types of ELTs General Types of ELTs Aircraft (General Aviation) Military (beepers or beacons) Personal (PELTs or PLBs) Marine EPIRBs Advanced (406/GPS)
Typical Aircraft ELT Operation 3 Switch positions--on, arm/standby, and off G-switch activated (Generally 9G) Activates ELT upon impact when armed May be manually operated by placing the switch in in the ON position
Can you test an ELT? Yes, with restrictions: First 5 minutes of the hour, no more than 3 sweeps Battery must be replaced after: One cumulative hour of use or 50% of useful life has expired FAR §91.207(c) Does not apply to our Practice Beacons Call nearest FSS in advance: 1 (800) WX-BRIEF Give a contact phone-interference happens on !
Inadvertent Activation of an ELT May Occur From Excessively hard landing Inadvertent change of switch position Removal of the unit activating the switch or G-switch Malfunction switch short battery leakage
Who is listening? SARSAT/COSPAS FAA Facilities FSS, Centers, Towers Airliners Only if pilot chooses Military Aircraft 243 MHz Required General Aviation Aircraft Thats us! Help the system work: monitor MHz Signal report is relayed to AFRCC
How SARSAT Works Receive 121.5, 243, 406 MHz Signals Orbiting and Geostationary Satellites Orbiting: SARSAT/COSPAS High Inclination (polar) orbits Geostationary: GOES Weather Satellites SAR payloads for 406 only Operated by Canada, France, Russia, USA They give us digital lat-long coordinates CAP Mission Coordinator plots these and assigns assets Ground teams must interpret for land navigation
System Operation Details SARSAT/COSPAS in polar orbit Calculates location of signal by measuring Doppler shift This yields a latitude and a distance
Narrowing the Search (SARSAT/COSPAS Only Narrowing the Search (SARSAT/COSPAS Only ) First pass Ambiguity
Where Is It? Second Pass average minute wait Ambiguity resolved 5-12 Nautical Mile Average Error
How do Different ELTs stack up? MHz ELT 12 NM Radius, 452 Sq Mi Ave. 6 Hour Notification 60 Milliwatt Transmitter 406 MHz ELT 2 NM Radius, 12.5 Sq Mi Ave. 1 Hour Notification 25 Milliwatt Beacon 406 ELT with GPS.05 NM Radius,.008 Sq Mi Ave. 5 minute Notification 25 Milliwatt Beacon
System Review ELT, PLB, EPIRB Signal Received AFRCC gets coordinates from SARSAT Appropriate CAP Wing is activated
False Alarms 97% of received ELTs are false alarms MHz: 1 in 1000 is an actual emergency (0.1%) 406 MHz: 1 in 8 is an actual emergency (12.5%) Why is a False Alarm a big deal? SARSAT can only monitor 10 ELTs at once (within footprint) bent-pipe repeater VERY easy to overload the system Blocks emergency communications Blocks the real emergency!
How should we treat an ELT? As an EMERGENCY! You cant know which ones are Distress ELTs And even the false ones are good training!
Transportation to Target Ground Teams generally will use vehicles for transportation to and from mission base Aircraft Coordination will get the Ground Team to the target the fastest If no aircraft is available: Vehicles provide enough speed and range to triangulate Close range may be required for signal acquisition
Direction Finding DF unit Measures equal strengths of signal not wholly accurate, but good enough! Therefore, when needle is centered, ELT could be either direction Needle always POINTS to the ELT (DF=Direct to the Flipping target) Use a TURN to TELL if the ELT is in front or behind you
DFing with the Little L-Per 6 Steps: use the full procedure every time! Turn the unit to Receive, check proper frequency and volume Turn the Sensitivity Knob to HALF SCALE This will prevent oversense and a good starting point Turn the unit to DF (Direct to the Flipping target) Turn at least one FULL circle, stopping and calling, Center! Check: Use Turn to Tell: the needle will point Direct to the Flipping target Use your compass, shoot an azimuth to get a bearing to the ELT
Direct to the Flipping, Turn to Tell
REC 1/2 DF Center Turn Shoot
Little L-Per Receive Mode Measures Signal Strength only From a direction of the arrows on the antenna (to your left) Use it with multiple centers (more than 2) to verify strongest path Due Reflections Thats most likely the true direction to the ELT
Reflections Caused by flat surfaces Hangars are notorious Rock wall, cliff, or mountains To beat reflections Check sensitivity half scale often Use RECeive mode Rubber ducky antenna Off-frequency tuning Usually strongest DF center is not a reflection
Triangulation Best method for ground troops to get an accurate fix when search aircraft support is unavailable You must be able to receive the signal Center up DF unit on the signal Take the magnetic bearing (shoot an azimuth) Correct for magnetic variation East is least, West is best Plot your bearings (draw a line) on map The ELT should be where the lines cross!
Lets See That
Body Shielding Body Shielding The BEST method of beating reflections at close range Can use L-Per Radio Shack JETSTREAM radio is better and CHEAP! At extremely close range, a 2m VHF radio unsquelched may work This works ok when trying to figure out a particular aircraft on a flight line, it will probably not identify a particular hangar Body blocks out the signal Called a NULL Null should be at your BACK
Off-Frequency Tuning Decrease sensitivity when: Sensitivity (L-Per) is at the minimum and signal is still too strong (full scale on receive) You dont get a null during body shielding You dont have a sensitivity knob (Jetstream) Shortening (Jetstream) or removing (Little L-Per) the antenna will also decrease sensitivity Off-Frequency tuning may be used any time you have too much signal, but this technique is especially effective during body shielding
I cant hear the signal! ELTs are limited to Line of Sight propagation You dont always need to hear the ELT Carrier wave may be broadcasting with no audible sweep Especially true in low batteries, or odd transmissions You can tell by DEFLECTION Good needle deflection generally indicates a signal that is strong enough to DF
What else can affect an ELT signal? Power lines EM Radiation If you get an actual ELT during a practice search, shut down all practice beacons. The signal on may be frequency shifted from your practice beacon! (often due to power lines) Fence Line (signal can follow) Coffee Can/Stovepipe effect Hangars Moving Target
How does an aircraft perform an electronic search? Aircraft use the same type of methods as used on the ground DF mode (most common) Wing Null Method (body shielding with the wing!) Signal Strength Aural Search (rare)
Before going home, silence the signal Before going home, silence the signal ! Sometimes thats the only goal! Methods of disabling an ELT: Switch off (not always effective!) Foil tent Grounding wire Remove battery Remove antenna The Sheriff is required for forcible entry Most folks will be very cooperative Ensure the aircraft operator is notified you disabled the ELT!
Summary You Should Now: Know what an ELT is and how it can be activated Understand why an ELT signal is an emergency Describe how CAP is called out on an electronic search Be familiar with these fundamentals: Plotting a SARSAT hit on a map (latitude/longitude) Direction finding - Little L-Per Operation Triangulation Body shielding Aircraft coordination/LORAN/GPS operations Ground Vehicle Operations