ELT and Air Operations Training
-- Schedule --- FAQ --- Levels --- Documents --- Knots --
-- Training Guide ---
March 25/29 1998
Instructor: Lauren Schiff
What do you need to think about in the woods when you're on a field task
looking for a plane?
Fuel- noxious fumes, flammable
Sharp metal, debris from crash may be hazardous and may be overhead as well as on ground.
Trees and power lines may be down where plane crashed
Look up!
What happens when an airplane crashes?
Many planes have an Emergency Locator Transmitter (ELT) This is equipment that outs out a radio distress signal at 121.5 MHz or 406 MHz upon impact. Here is what they look like:
Figure 1: Two ELT models
The Civil Air Patrol (CAP) is most likely to respond to these emergency signals.
NASA quotes that "only about 1% of all ELT searches are for actual
aircraft crashes. The other 99% are due to inadvertent activation of the ELT." [Source] However, if BRMRG
is activated, there is good reason to believe that the search is for an actual plane.
What does an ELT sound like?
ELT Sound Courtesy of Civil Air Rescue
Emergency Service
How long does the ELT emit a signal?
"Depends on a lot of factors. The design criteria is that they transmit for at least 48 hours at 0-degrees, some will transmit much longer if the weather is warm, the battery fresh, etc. Or they will transmit for less if it's colder, if the battery hasn't been replaced when it was supposed to, etc." --Richard A. De Castro -N6RCX NREMT SAR Tech
How far does the signal propagate?
"The USMCC (the people running the SARSAT program) still claim that the satellite locates ELTs within 11nm 90% of the time and within 3 nm for 406MHz beacons." -- LtCol Mark Fowler ACC/AFRCC
If the ELT antenna is pointed upright, it will propagate further.
| 121.5 MHz | 406 MHz | |
| LOCATION ACCURACY | 12 miles | 2 miles |
| COVERAGE | Local | Global |
| SIGNAL POWER | 0.1 Watt | 5 Watts |
| SIGNAL TYPE | Analog | Digital |
| ALERT TIME | 2 Hours | Instantaneous |
| DOPPLER LOCATION | Two Passes | Single Pass |
| GPS LOCATION | None | 100m Accuracy |
Figure 2: Straight line propagation for two types of ELT signals. We have equipment to search for 121.5 MHz. Source: NOAA [ http://psbsgi1.nesdis.noaa.gov:8080/SARSAT/406-121.html ]
In general, what chance of survival do the subjects have?
"AFRCC statistics" quote that 65% of general aviation crash victims do not survive impact. Of the 35/100 survivors, 21 are injured and last about a day while 14 are uninjured initially and have a "half-life" of about 3 days. -- LtCol Mark Fowler ACC/AFRCC
"ELT normally survives only when the victims can and do. If the crash is so bad that the ELT is destroyed then the no one can likely live through it." This is not always true but I yet to find a Lost or downed A/C with a proper maintained ELT that was damaged w/survivors, in 11 years of SAR work." -- Brandon Brown 1Lt. CAP, Dir of Emergency Services; HQ Group I TX Wing, Chief of Communications; Panhandle Search and Rescue
How do we use the ELT to locate the plane?
L-pers are direction finding (DF) equipment used to locate the source of the signal. These receivers give you two types of information: direction and strength of signal.
Figure 3: L-per
A. Direction
- Set frequency, DF mode, SENs minimum, VOL at 12 o'clock.
- Turn SENS up until meter needle goes left or right and signal is audible.
- Turn toward needle. You are facing the target.
- Left to right needle swing is normal when walking, driving, or flying. Follow headings that keep left and right swings about equal.
- As volume increases and/or needle gets too sensitive, decrease SENS. Slight left-right swing and audible signal is enough.
- The closer to target the more rapidly volume and sensitivity increase.
- To evaluate the quality of bearing, turn a full circle. If needle centers more than twice 180 deg apart, move to another location.
- Shoot a bearing to the source of the signal.
Figure 4: An upright arrow will result in a straight bearing to the ELT. Move the L-per to achieve this.
Figure 5: The above diagram indicates the needle readings for the L-per relative to the location of the ELT. Note that the needle will be straight up when you are both behind and in front of the ELT! Test the direction by moving your body to the left or right. If you twist to the left and your needle swings back to the right, the ELT is ahead. However, if you twist to the left and the needle follows you, the ELT is likely behind you.
B. Signal Strength
Directions:
- Set Frequency, REC mode, SENS minimum, VOL at 12 o'clock
- Turn SENS up until the meter goes up and the signal is audible.
- Turn in a circle until needle goes furthest upscale. In this position, the arrows on left arm of antenna point to signal source.
- Without changing controls, turn antenna until horizontal with ground. A noticeable increase in signal strength means transmitter is horizontal.
- As volume increases and/or needle nears right-hand stop, decrease SENS.
- The closer to target, the more rapidly volume and sensitivity increase
- To evaluate quality of bearing, turn in full circle. if multiple readings of about equal upscale movements results, move to another location.
- The stronger the signal, the further right the dial will swing.
The signal will bounce!
Be careful, because the signal is very likely to reflect off of mountains and other large objects. This may cause you to think that the ELT is in a position that it is not. This may happen multiple times before the signal reaches your receiver. Note that the signal can also be blocked by large objects in your path. Stay away from things like buses and large buildings when shooting bearings.
Figure 6: Signal reflected off of a mountain.
Strategy
Figure 6: Emitter is likely to be near the triangle of cross-section.
7. Try to leap-frog from last signal point to find downed aircraft
Figure 7: Leap-frog to emitter source
Don't forget basic logic behind plane crashes!
"In mountainous terrain, we (California Wing, Civil Air Patrol, of which I'm the Ground Team Training Officer, but this is NOT an official statement) seem to find them about 500-800 feet below the ridge lines. We think this is because the perception from the pilots seat is that this will allow the aircraft to clear the ridge, and by the time they figure out they won't, it's too late to do anything about it." -Richard A. De Castro -N6RCX NREMT SAR Tech
The USMCC (the people running the SARSAT program) still claim that the satellite
locates ELTs
within 11nm 90% of the time and within 3 nm for 406MHz beacons. --Fowler M LtCol ACC/AFRCC
The Find Scene
Treat it as if it's a crime scene
First thing: establish a perimeter and keep people out if possible
You cannot physically keep press/others out, but you can remind them that it's a federal
crime to tamper with a crash.
Determine status of subjects and if the number of bodies matches the number of passengers
(survivors have been known to wander off.)
DOCUMENT everything: position of wreckage and subjects, movements made of debris, etc.
Diagrams are good.
How to approach the plane
Upwind-because of the danger of noxious fumes.
Uphill, because fuel and precariously perched parts go downhill.
Other aspects of the downed aircraft search to be aware of:
[
http://psbsgi1.nesdis.noaa.gov:8080/SARSAT/homepage.html
]
Mit's statement about flying on searches:
Here is a note about the risks of flying-- because if you stick with BRMRG long enough, you will have the opportunity to do so ... and it is important that you understand the risks of flying during SAR before you are put in a real-time decision. This message is courtesy of Mit Robertson, BRMRG member and private pilot. Following is a recent news posting. No one >should agree to fly without reading this first. Please take this seriously!
Factors to consider when riding in single-engine planes on searches ---- When flown by competent, careful pilots, a well-maintained small plane is a safe mode of travel. I have no reason to believe that CAP aircraft and pilots are anything other than well-maintained and careful & competent, respectfully. However, flying search missions presents some inherent, irreducible risks over and above those generally associated with small planes.
An inordinate number of small plane accidents are weather related, but fortunately, air tasks are always flown in good weather. (If you can't see, there's no point in flying.) That's one factor in your favor. However, the missions must be flown reasonably close to the ground to afford an acceptable view. In some cases, a plane that suffered an engine failure would not be able to reach an ideal (or even acceptable) landing site. (Generally pilots fly high enough to allow an engine out glide to a field, road, etc.) Furthermore, turbulence associated with mountains (where aircraft searches often occur) can produce downdrafts that exceed a Cessna's ability to climb. In extreme cases, these downdrafts can cause a crash.
The basic point to this is that search flying, in comparison to other small plane flight, requires a pilot to put his aircraft in positions where factors beyond his control are more likely to cause a crash. As for the actual level of risk this entails, I have no idea. Comparing the risk of flying in a small plane with riding in a car is difficult. The statistics only allow a very apples and oranges comparison. It is not the case, as with commercial flight, that planes are significantly safer than cars. The best estimate seems to be that you are less likely to be in an accident, but more likely to die in a small plane. Given the conditions in which we often drive to searches (fatigued, late at night, narrow and sometimes slick roads...), I suspect the risk in flying a small plane is similar to the risks we already take.
Mit Robertson
BRMRG, Private Pilot
______________________________
http://www.avweb.com/newswire/news9745.html
CAP Aircraft Crashes During SAR Mission
A Cessna 182 operated by the Civil Air Patrol's California Wing crashed November 3 during a mission in search of a Cessna 206 missing since October 26. Aboard the C-182 were three members of the San Jose Senior Squadron 80. According to CAP HQ, the 182's crew failed to respond to a routine roll call of aircraft participating in the search and an aircraft in an adjacent search grid noticed smoke and diverted to the site. The wreckage of the CAP aircraft was spotted immediately and a California Highway Patrol helicopter participating in the original search diverted to the crash scene. Rescuers airlifted the sole survivor, Capt. Joseph E. Lawrence, to the University of California at Davis Medical Center for treatment of severe burns to his face and hands. , Capt. Jess Ceniceros and Lt. Col. Frederick Nettell, both highly experienced SAR pilots, were killed in the crash. The crash is under investigation.
The missing Cessna was subsequently found two days later. All four on board, Ron Lukas, his wife Lisa Lukas, step-brother Steve Schantz and friend Eric Schleier all of Carson City, Nevada, died in the crash..They had departed the Douglas County Airport in Minden, Nevada bound for Calaveras County Airport in California.
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Other links
Air Force Rescue Coordination Center [ http://www.acc.af.mil/afrcc/ ]
SARMAN [ http://www.sarbc.org/nat.html ] contains Canadian electronic search guidelines
NASA Goddard Space Flight Center - Greenbelt, Maryland Search and Rescue Mission Office [ http://poes2.gsfc.nasa.gov/sar/sar.htm ]