 There
are several different ways to search for multiple avalanche victims. This page explains
transceiver-specific as well as
generic multiple burial search techniques that can be used with any transceiver.
The technique you use will depend on the type of avalanche transceiver you use (i.e., whether it provides multiple burial features) as
well as the number of rescuers that are available. If you are the only rescuer, you will use your transceiver to search for the first
victim, probe, and start digging. After reviving the first victim, you will
simply turn off his beacon and use your transceiver to search for the next victim. You won't have the luxury of having other rescuers
shovel while you search for a second victim (while the first victim's transceiver continues to transmit).
The following instructions explain two methods of searching for multiple victims using any avalanche transceiver.
| 1 |
Locate the first victim using the normal search techniques. (This is the red line in the following
illustration.) |
| 2 |
Your partners will begin digging for the first victim. |
| 3 |
Move approximately three meters from the victim. The
distance indicator on your digital beacon should display approximately
three meters. (If you have an analog beacon,
turn down the sensitivity so it just picks up the first victim.) |
| 4 |
 Slowly walk in a circle
around the victim while watching the distance indicator. You are looking for a sudden change in the distance that is less than
the three meters you are from your first victim. Likewise, watch for a sudden change in the
direction indicator that does not point to your first victim. (With an analog
beacon, you are listening for a second beacon.)When a change is noted, use the secondary
and pinpoint search techniques to locate the second victim. If you complete the circle
without finding a second victim, expand the circle by three meters and again circle the first victim.
If your transceiver leads you back to the first victim, return to the previous three meter circle and repeat the process.
On the illustration shown here, the red line represents your initial search path to locate the first victim. You would then move
three meters from the victim and circle the victim as shown by the smaller blue circle. In this case, your transceiver will continue
to show the distance to the first victim (approximately three meters), because this victim is still closer to you. After completing
the first circle you would enlarge the circle by three meters and again circle the first victim. In this second circle you should
expect the distance to show approximately six meters (because you are now
six meters from the first victim). However, as you near the second victim your transceiver will drop from the expected six meters
down to approximately 1.5 meters (in the above example). You should then use the secondary and pinpoint search techniques to locate
the second victim.
|
| 5 |
If a second victim is found and victims are still missing, you should return to your last location on the circle and complete
the circle. If you complete three circles (approximately 9 meter radius)
without finding a victim, you should return to your primary search. |
The expanding circle technique works well and is easy to learn. The disadvantage is you have
to cover a lot of ground and walk uphill to complete the circles.
|
Details on the micro search strip technique can be found here
 .
| 1 |
Locate the first victim using the normal search techniques. (This is the red line in the following
illustration.) |
| 2 |
Your partners will begin digging for the first victim. |
| 3 |
Move approximately three meters from the victim toward the direction
that you approached the victim. Your digital beacon should display approximately three meters. (If you have an analog beacon,
turn down the sensitivity so it just picks up the first victim.) |
| 4 |
 Now begin a
primary-search-like route, but this time with approximately three meters between each
pass. As with the expanding circle technique, you are looking for an unexpected change
in the distance or direction relative to the first victim. When a change is noted, use the
pinpoint search technique to locate the second victim. If your transceiver leads you
back to the first victim, return to your previous micro-strip location and continue searching.
On the illustration show to the right, the red line shows your initial search path which located the first victim. You should
then move a few meters up hill and continue searching. Your directional indicator will continue to point to the first victim and
the distance will increase/decrease as you move further/closer to the first victim.
When you are closer to the second victim than the first victim (this is the point where the blue line changes to a dotted line
in this illustration), your transceiver will point in a different direction and the distance indicator will drop to display the
distance to the second victim. You can then use the pinpoint search technique to locate
the second victim.
|
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When there are multiple victims, the searching transceiver receives a complicated collection of signals. And as the number of victims
increases, the amount of time that the various signals overlap also increases. Modern digital transceivers analyze the rhythm and signal
strength of the various signals to estimate the number and location of the victims. These transceivers then allow you to "suppress" a
specific signal. This is done by ignoring the signal based on the previously analyzed rhythm. (Manufactures refer to this as either
"marking" or "flagging.")
If your avalanche transceiver mistakenly returns you to a victim you suppressed, you should repeat the suppression process.
When there are 3 or 4 victims, it becomes almost impossible for the searching transceiver to separate the signals due to signal overlap.
It is also more difficult for the transceiver to separate the signals if the victims are located close to each other, because the searching
transceiver cannot use signal strength to help distinguish between the signals. Due to these challenges, you should still learn and practice
the generic multiple burial search techniques regardless of the type of beacon
you own. You should also reduce the likelihood that multiple people will be buried by not exposing multiple people to the same avalanche
hazard.
It is very important that you read the user's manual that comes with your beacon and that you practice these
multiple burial techniques. None of these techniques are intuitive enough to figure out after the avalanche strikes.
As with all avalanche transceivers that can suppress a signal, you should locate the victim with your probe
before suppressing the signal.
You can read the details of multiple burial tests here.
You can estimate the number of victims when using an analog beacon by listening to the rhythm and cadence of the beeps. For
example, if you hear beep-beep, pause, beep-beep, you know there are two victims (the closest beep will be the loudest). Turn
the sensitivity down to isolate the nearest beacon and then search using analog techniques. After locating the first victim, use
the generic multiple burial techniques to locate the other victims.
The multiple burial feature in the ARVA Advanced was updated for the 2007/2008
season. The ARVA 3Axes uses the same technique. The Mark technique on these transceivers
is similar to the Ortovox S1, Pieps DSP, and Barryvox Pulse.
When multiple signals are received, the
 icon appears on the
screen and the transceiver locks onto the closest victim. After locating the first victim, you can suppress (a.k.a. "block") the
current victim's signal by quickly switching from search, to transmit, and then back to search (by toggling the "nose" switch).
The Advanced then directs you to the next victim. This feature worked well in my testing of the ARVA Advanced. You can learn more
about searching for multiple victims in the user's manual.
Optionally, you can toggle the Advanced or 3Axes to analog mode (by holding both the "+" and "-" keys pressed for a few seconds)
and then use the analog multiple burial search technique.
When multiple signals are received by the ARVA Evolution+ or the
ARVA Evo3, the
icon appears on the
screen and the transceiver locks onto the closest victim. After locating the first victim, take "one or two steps backwards" in
the direction you came, then quickly switch from search, to transmit, and then back to search (by toggling the "nose" switch).
This activates a "scan mode."
Hold the transceiver very still while it scans for the transmitting beacons. It will then display information about each of
the transmitting beacons. The display rotates through this information approximately five times. During each rotation, the screen
will display the direction and distance to one of the victims. Head toward one of the victims that you haven't found. If the transceiver
returns you to one of the victims you have already located, repeat the Scan mode (by toggling the switch).
In my testing of the Evolution+ multiple burial mode, the scan mode did a good job of stating the distance to the burials,
but the direction indicator was only mediocre in pointing the correct direction.
The Barryvox 3000 shows if there is one, or more than one, transmitter
by displaying a small icon. This is helpful when determining if there is more than one victim, although the 3000 does not have
any multiple burial search features. It is probably best to use the digital search to find the first victim, and then either use
a generic multiple burial search technique or switch into analog mode
and use the analog multiple burial search technique.
An LED on the Ortovox D3 lights up if there is more than one victim. The D3 does
not have beacon-specific functionally to search for multiple victims so you should use one of the
generic multiple burial search techniques.
The Ortovox S1's approach to multiple victims is unique, because the S1 can display multiple
victims on the screen at one time. The distance to each victim is also displayed. (The Pulse
can display information on multiple victims, but not in a graphic format.)
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Mark
Button |
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After locating the first victim, you can suppress that victim by pressing the "Confirmation" button. A flag then appears on
the screen where the victim was displayed and the S1 will guide you to the next victim.
Pressing the Confirmation button a second time will unmark the victim. In my
testing with two victims, the S1's marking and unmarking were excellent.
The user manual mentions that you cannot unmark a victim if several victims are transmitting within a 3 meter radius.
All avalanche transceivers that allow you to suppress a victim must deal with the challenges of overlapping signals. If the
S1 is unable to separate the signals and display them on the screen (as might happen when there are 3 or more victims), the S1
will reduce its reception range until the information can be processed and displayed. If the S1 is unable to separate the signals,
the "Stop" hand is displayed. You should then stand still as the S1 analyzes the signals.
If there are 3 or 4 transmitters and the S1 is unable to separate the signals, a screen is displayed showing "4+". This screen,
although it is far from intuitive, is asking if you want to limit the range to 5 meters. You can then press either the Confirmation
or Rejection buttons. After confirming that you want to limit the range to 5 meters, you should then use the
expanding circle or micro strip technique
to locate the victims.
And finally, there is a "Search for more than 3 victims" mode (which can be selected from the menus). In this mode, the first
victim is located in the normal manner. After suppressing the first victim, the transceiver automatically reduces the range to
5 meters.
These additional features and icons may be difficult for the average rescuer to deal with during a life-or-death emergency,
but the basic search, mark, and locate the next victim features work well.
When multiple signals are received by the Pieps DSP, little men ( )
are displayed on the screen indicating the number of victims.
 |
| Three Victims |
After locating the first victim, you can suppress that transmitter without digging up the victim by pressing the Mark button
for approximately three seconds (until the distance indicator changes to "--").
A box will surround that little man and the DSP will guide you to the next victim.
 |
| Victim Marked |
In my multiple burial testing with two victims (using the version 5.0
software), the DSP's suppress feature worked very well. Earlier versions were less consistent in their ability to suppress a signal.
The Mark feature works best if you hold the DSP very still when pressing the Mark button (I noticed this more using earlier
versions of the DSP software).
The DSP also has a scan function. To enable it, press and hold the "(((" (or "?") button for a few seconds
while in search mode. The DSP will then display the number of transmitters within 5, 20, and 50
meters.
|
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| Victim Marking |
| |
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| Victim Selection |
| |
The Barryvox Pulse displays silhouettes ( )
to indicate the number of victims (up to three). By default, the Pulse guides you to the nearest transmitter. After locating the
victim, suppress the victim by pressing either button. This suppresses that signal and the Pulse will point you to the next
victim.
When using the advanced profile, the Pulse lets you rotate between the
victims by pressing the left button. As you rotate between the victims, the distance
and direction indicators are updated.
Also when using the advanced profile, the Pulse allows you to unmark a previously suppressed transmitter (as does the
Ortovox S1). The selecting of victims and unmarking requires a little learning, but it worked great
during my multiple burial testing.
The Pulse does not display the Mark command until you are within 6 meters. A warning is displayed if you attempt to Mark a
victim that is more than 3 meters away.
 The
Tracker DTS and the Tracker2 have a "special mode" button that narrows the reception "arc" from 360° to 75°
in front and behind you. When you locate the first transceiver, you can then press the special mode button to narrow the arc and
only search for signals in front and behind the transceiver.
This assumes that you know there are multiple
victims, because the Tracker DTS does not display an indication of multiple signals whereas the
Tracker2, does.
The special mode definitely requires practice. I think it's best to master the
generic multiple
burial search techniques and then learn how to use the special mode feature.
The Tracker2 has a multiple burial light that illuminates when it
receives more than one signal. If two or more transceivers are transmitting within 5 meters of the receiving unit, the light blinks.
The Tracker2 has includes the same "special mode" as the
Tracker DTS. The Tracker2 does
not have the ability to "mark" (i.e., ignore) a transceiver (as found in the Ortovox S1,
Pieps DSP, and Barryvox Pulse).
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| Barryvox Pulse |
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| Pieps DSP |
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| Tracker DTS |
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| Ortovox S1 |
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