Transcript SARSAT System - Minnesota Wing Civil Air Patrol

SARSAT System
Minnesota Wing
Air Branch Director Course
COSPASS-SARSAT History
• Initially developed under a MOU between the
former USSR, USA, Canada and France in 1979.
• Operational use started in 1982 with a crash of a
light aircraft in Canada in which three people
were rescued.
• After some a test and evaluation phase, the
system became fully operational in 1985.
• COSPASS-SARSAT has been instrumental in the
rescue of over 24,000 lives worldwide.
What is it?
• A network of satellites used to detect
emergency beacons used by persons in
distress.
• Contains both Low Earth Orbit Satellites
(LEOSAR) and Geostationary Satellites
(GEOSAR)
• Monitors only 406 MHz beacons.
– Monitoring of 121.5 MHz beacons ceased on 1
February 2009.
Two types of Satellites:
• GEOSAR: Receives beacon identification almost
instantaneously. Location information available if
encoded in beacon message. No coverage near
Earth’s poles.
• LEOSAR: Used to provide beacon identification and
location information. Global coverage, but not
instantaneous.
How are beacons detected?
• GEOSAR:
– Receives 406 MHz Data burst transmission which
contains a beacon identification number.
– Instantaneous activation of the SAR System is
possible.
– If equipped, the beacon may also transmit it’s
lat/long as part of the data burst.
• If so, instantaneous location is possible.
• If not, must wait for LEOSAR satellites must determine
the location.
How are beacons detected?
• LEOSAR: Uses a Doppler shift to detect beacon locations.
• Takes a minimum of two passes to solve ambiguity and
create what is called a “Merge”.
• With 406 MHz beacons, accuracy is within 5 nm.
• Satellite is in range on average, once every 45 minutes.
406 Beacons
• Owners are required to register the new
beacons. This information is kept in a
database for retrieval if their beacon is
activated.
• Many false alarms are solved with a phone call
to the owner asking them to turn their beacon
off.
• Transmit a very low power 121.5 signal for
rescue teams to transmit.
Doppler Shift Position Solution
• Doppler shift on
121.5 MHz
provides two
candidate positions
• A second satellite
pass is needed to
determine which is
the correct one
Two equidistant candidate position
solutions – these are called
“elementals”
Satellite location at
Doppler
zero shift
Doppler Shift Position Solution
• Doppler shift on
121.5 MHz
provides two
candidate positions
• A second satellite
pass is needed to
determine which is
the correct one
Position that agrees with 1st
satellite – this is called a
“merge”
2nd Satellite
location at
Doppler
zero shift
How do we get called?
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Emergency Beacon Signal is received by Satellite
Transmitted to Local User Terminal
Data received by Mission Control Center
Sent to Rescue Coordination Center (RCC)
Air Force Rescue (AFRCC) will investigate if they
have owner information or can work with local
airports to resolve.
• If unable to resolve quickly, AFRCC calls CAP Duty
officer and opens mission.
• Duty officer alerts units.
What about 121.5??
• AFRCC is still issuing missions for 121.5 MHz
beacons even without SARSAT data.
• Airborne reports are the only method of
detecting the beacons.
• Airborne reports are far less accurate than
SARSAT hits.
• Depending on the altitude of the reports, the
search area could be hundreds of miles in
diameter.
Old Beacons vs. New
• Actual Distress Rate:
– 121.5: 2% or 1 in 50 is genuine
– 406: 8% or 1 in 12 is genuine
• Comparison of 121.5 and 406 MHz beacons:
What information to expect?
• 121.5 MHz Beacons:
– Airborne Reports
– Reports from Airport FBOs if AFRCC called them.
• 406 MHz Beacons:
– Tail number (if in an aircraft)
– Owner Information (if registered)
– Latest SARSAT Merge
– GPS coordinates of beacon if it is equipped with a
GPS unit.
References
• COSPAS-SARSAT Website
– http://www.cospas-sarsat.org/
Questions?