 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
coarse and
fine 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 above illustration, 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 smallest 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
coarse and
fine 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
signal 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 signal-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 fine
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
fine search technique to locate the
second victim.
|
 |
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 a signal based on the previously analyzed rhythm (the
buried beacon
continues to transmit a signal). Manufactures refer to this process of ignoring a signal
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.
Some of the newer digital transceivers will occasionally report multiple transmitters
when receiving a signal from an older
Ortovox F1. This seems to be more
common with the Tracker2 and the Pieps DSP.
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 3+, Ortovox S1, Pieps DSP, and Mammut 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 (the Evo3+ displays 1, 2, 3, or 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.
 When
a signal is received by the ARVA Axis or
the ARVA Link, the
silhouette appears on the left side of the display. If multiple signals are
received, additional silhouettes appear. Depending on how the signals overlap,
the Axis and Link can display up to five silhouettes.
  |
| ARVA Axis |
When searching with the Link you can use the side-buttons to move between the
silhouettes. You can then see the distance and direction to each signal.
If there is a signal that is closer than the signal you are pursuing, the
symbol appears. With the Link, you can continue searching for the more distant
signal or select a different victim. The Axis will automatically switch to the
nearest signal.
When you are within 3 meters of a transmitter (or 5 meters if you change an
internal configuration setting), the
symbol appears on the screen.
Pressing the button in the center of the search switch instructs the transceiver
to ignore that signal.
As with the Mammut Pulse, the ARVA Link can use
the additional information that these transceivers transmit on the "w-link"
frequency to better determine the number of transmitters and to do a better job
ignoring a signal
after marking.
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.
 The
Mammut Element displays one or two silhouettes to indicate one or two victims. If
there are more than two victims, the Element displays two silhouettes and a "+"
sign.
When you are within three meters of a transmitter, a large checkmark appears
in the lower-right corner of the display. Pressing the button places a checkmark
next to the first silhouette, highlights the
 next
silhouette, and the direction indicator is updated to point to the next transmitter.
In my relatively limited testing of the Element's multiple burial commands, it
was as excellent as the Pulse, but with a more intuitive interface.
|
|
| Marking |
| |
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| Victim Selection |
| |
The Mammut 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. During testing, the Pulse's marking was excellent.
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. This is a good reminder, because you should contact the victim with your probe
before marking him.
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 3+ indicates
the number of transmitters by displaying up to three people just below the distance
indicator. If four or more beacons are transmitting, the transceiver displays "4+"
to the left of the people.
The 3+ will initially direct you to the closest transmitter. After locating the
person with your probe, press the Marking button on the
transceiver to ignore the current beacon. That person will then be displayed on
a black background and you will be directed to the next person.
If several beacons are transmitting and the signals are overlapping (a situation
that will prevent any transceiver from accurately searching), the 3+ will display
the estimated distance to the closest transmitter without displaying a direction
indicator.
The 3+'s handling of multiple burials is solid. There is only one button on the
face of the transceiver, so there is no mistaking which button you should press.
The indication of the number of burials is clear and obvious. And during our testing,
the marking featured worked perfectly. Simply press the button once (even if the
transceiver isn't held perfectly still) and the 3+ will point you to the next
transmitter. I tested this feature with both two and three transmitters, using the
same brands as well as different brands of transmitters, and the marking was excellent.
The 3+ does not include the ability to unmark a previously marked transceiver
(which the Mammut Pulse and
Ortovox S1 do). I think that was a good decision,
as the additional user interface probably adds more confusion than benefit. If you
want to unmark a previously marked transceiver, momentarily toggle the 3+ between
send and receive.
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.)
|
|
|
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 or Tour, little men ( )
will be displayed on the screen indicating the number of transmitters.
|
| Three Victims |
After locating the first victim, you can instruct the searching transmitter to
suppress (i.e., ignore) that signal by pressing the Mark button for approximately
three seconds (until the distance indicator
changes to "--"). A box will surround that little man and the transceiver
will guide you to the next signal.
|
| Victim Marked |
In my multiple burial testing
with two victims (using the version 5.0
software), the DSP's suppress feature worked well. Earlier versions were
less consistent in their ability to suppress a signal.
The Mark feature works best if you hold the transceiver very still when pressing
the Mark button (I noticed this more using earlier versions of the DSP software).
The DSP (but not the
Tour) also has a scan
function. To activate this function, press and hold the Scan button (which is
labeled either "(((" or "?") while in search mode. The DSP will
then display the number of transmitters within 5, 20, and 50
meters. This scan
function also "unmarks" any transceivers that were suppressed using the
Mark button. To unmark transceivers using the one-button
Tour, turn the Tour off and then back into Search
mode.
 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 light is not intuitive.
The Tracker2 includes the same "special
mode" as the Tracker
DTS. The Tracker2's user manual states that the special mode "is an advanced
feature designed to assist expert searchers in specialized multiple burial situations."
The Tracker2 does not have the ability to "mark" (i.e., ignore) a
transceiver.
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| Mammut Pulse |
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| Pieps DSP |
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| Tracker2 |
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| Ortovox S1 |
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