SPOT Versus ELT Analysis (Long)

All,

Some of the recent RAS articles about SPOT got me thinking that this
is a nice device with some important safety features. I decided to do
a quick and dirty analysis of the benefits of the SPOT device versus
the various ELT/PLB devices. Both basically fulfill the same
function, which is to alert someone to come and get you out the jam
you managed to get yourself into.

Below is a comparison of the various attributes of the SPOT device
PLB’s. I’d enjoy any comments that you might have.

Disclaimer: I own an ACR MicroFix PLB.

Background – Many/most (all?) powered aircraft, and some non-powered
aircraft contain ELTs (Emergency Locator Transmitter). The simplest
form of an ELT sends out an emergency signal at a specific frequency
(121.6 Mhz). This emergency signal can be listened for with standard
aviation receivers and then tracked to its source. In the US this
function is often performed by the Civil Air Patrol. Newer ELTs
(operating at 406 Mhz) can transmit GPS location information via
satellites orbiting overhead. A US government agency (NOAA) is then
alerted to the emergency and provides the GPS coordinates to the
appropriate rescue personnel. PLB (Personal Locator Beacons) are
similar in function, using GPS and 406 Mhz, plus being more compact
than ELTs, and typically less expensive. SPOT devices are identical
in function to PLB’s except they are smaller & lighter and transmit
their emergency information via commercial (non-government) satellite
system.

Cost - The SPOT is about $150 while the smallest personal PLB (ACR
MicroFix or ResQFix) is $650. Advantage SPOT it would seem. However,
SPOT requires a $100/year subscription fee (PLB is free). This makes
the cost break even point of 5 years between SPOT and this particular
PLB.

NOTES on Cost: I simplified this analysis by assuming that the cost of
battery replacement and future retail price discounts would not be a
factor. SPOT’s lithium batteries are to be replaced yearly while the
ACR MicroFix’s battery every 5 years). If you want SPOTcasting
(continuous monitoring), there is an extra $50 per year charge (break
even at 3.3 years). PLB’s don’t have a SPOTcast-like monitoring
feature. Important: Spots are being handing out FREE at the 2008 EAA
Airventure (Oshkosh, WI) show from July 23 – Aug 8 (http://
www.airventure.org). However, you must immediately sign up for the
$150/year SPOTcasting plan and also be an EAA member. See
http://www.findmespot.com/eaa.aspx for details. This would equate to
a cost break even point of 4.33 years (ignoring EAA membership
costs). A final aspect of cost, which I have not included, deals with
the potential cost of the first responders (fire, police, rescue,
etc).

Ruggedness – My impression is that the PLB’s (and certainly ELT’s) are
build to a more stringent standard than the SPOT devices. But to be
honest, I haven't researched this too much. Comments?

Monitoring Agency - PLB’s are monitored 24x7 by a government agency
(in the US this is NOAA). SPOT is monitored 24x7 by a private
concern. Which group is more viable in the long term remains to be
seen.

Monitoring Satellites - PLB’s are using government based satellites.
SPOT uses a privately owned satellite system. Which one is built and
maintained better also remains to be seen.

Emergency Response - Does anyone know how fast the “typical” emergency
response would be from first signal activation to first deployment of
the local emergency personnel (obviously the time to final rescue
would differ enormously)? Is SPOT any better or any worse than NOAA
in the US? I do have to wonder if, in an emergency, whether the non-
governmental GEOS team which monitors the SPOT system will be able to
contact a (non-US) government agency as quickly and efficiently as the
government based NOAA organization. Does NOAA carry more weight to
get non-US emergency teams to answer the phone and come to your
rescue? See http://www.magazine.noaa.gov/stories/mag96.htm &
http://www.geosalliance.com/ for some details.

Coverage – While I bought my PLB specifically for soaring use, it has
been taken on trips to Borneo and Haiti (as a just-in-case tool). GPS
(based PLBs) have worldwide coverage. SPOT coverage misses some areas
of sub-Saharan Africa, India, Micronesia and the north and south
poles. While these are not exactly prime soaring locations, I bring
this up to make a level comparison. http://www.findmespot.com/ExploreSPOT/Coverage.aspx

Batteries – All these devices rely on batteries. The SPOT FAQ says
that a set of lithium AA batteries will last for one year (non-
SPOTcasting mode). A PLB’s battery is designed to last for ~5 years
between replacements. Because the lithium AA batteries are
approximately 5x the replacement cost of the specialized PLB’s
battery, this ends up being a wash. During emergency use the SPOT is
rated for 7 days (911 mode) while the MicroFix PLB is rated for 40
hours. This time difference is not as critical as it would seem as
long as both GEOS and NOAA get the all important GPS coordinates in
the first few minutes or hours. The critical element is, will the
batteries be fresh when needed? This points to SPOTcasting (battery
life is 14 days) users needing to be rather religious about replacing
their batteries often or risk having a dead unit on their hands when
the chips are down.

Size/Weight - SPOT (4.38 x 2.75 x 1.5 inches) is the same size as the
MicroFix (5.85 x 2.21 x 1.4 inches), 18 cubic inches in both cases.
However the SPOT is 36% lighter, 7.37 oz versus 10 oz, the difference
primarily due to the lithium batteries being used.

Triggering – Unlike ELT’s, both SPOT and PLB devices must be manually
triggered (in emergency use).

Antenna – The antenna on the SPOT is internal while the antenna on the
MicroFix PLB is external. In my experience, external antennas provide
better reception and transmission. However, I don’t know if this
makes a difference with these types of devices.

Conclusion – I think that there are two key points, and two lesser
points, that are important to be considered.

First, the lesser points of size and battery life. Both devices are
basically the same size and small enough to be easily carried. Will
either or both grow smaller as technology advances? Undoubtedly. As
to battery life the SPOT is the clear winner (emergency use only) but
as I stated before, I am unsure if this is truly a critical element in
the analysis.

Next, the primary point of cost and the combination of coverage/
response/monitoring.

Cost - everyone’s primary metric. Obviously, the initial outlay to
obtain a SPOT is much less (4x) than the MicroFix. However, as we all
know from life with cellular phones, service charges can quickly
invert this equation. I fully expect to keep my PLB for more than 5
years and I suspect the SPOT users feel the same about their device.
Crunching the numbers makes this a tie between the two devices.

Finally, let’s look at the trickier coverage/response/monitoring
analysis. I believe that it comes down to the organization behind the
device. At this point in time I am still leaning towards PLB’s as the
item of choice. My reason is that when the chips are down, I would
rather have the reliability, capabilities, contacts and dedication of
a government agency rather than a private enterprise.

My $0.02.

- John “67” DeRosa

Web Links
http://www.findmespot.com
http://www.adventuretrak.com
http://en.wikipedia.org/wiki/Emergen...or_Transmitter
http://www.acrelectronics.com/microfix/microfix.htm
SPOT use video at: http://www.youtube.com/watch?v=-q2um6vGERY