The Science Of Survival

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The Anatomy of a Rescue

Cospas Sarsat - International satellite system

Learn how a rescue works.

1. Distressed mariner/outdoor adventurer/pilot activates beacon (EPIRB, PLB, ELT).

2. Beacon transmits a 406 MHz emergency message containing your Unique Identifier Number (UIN) to the LEOSAR (polar orbiting) and GEOSAR* (geostationary) satellite systems.

3. The satellites relay the 406 MHz emergency message to a ground station called the Local User Terminal (LUT). The LUT calculates the location of the signal by measuring the Doppler shift caused by the relative movement between the satellite and the beacon and forwards the location to the Mission Control Center (MCC).

4. The MCC continues to receive information from additional satellite passes and further refines the beacon position (2.3 nm search radius). An alert message is generated that is combined with the registration information from the database and is forwarded to the appropriate Rescue Coordination Center (RCC).

5. The RCC makes contact with the persons listed in the database to verify the existence of an emergency and gathers additional information about the beacon users. The RCC will dispatch the closest, capable Search and Rescue (SAR) forces.

6. Local SAR forces launch a rescue mission and use the 121.5 MHz homing signal to pinpoint the beacon.

* On average, worldwide, this notification (steps 2 through 5) take up to one hour for non-GPS beacons. For self-locating beacons that provide GPS position data in their first transmissions, the search radius is reduced to .05 nm (100 m) and the notification can take as little as three minutes. (Data provided by Cospas-Sarsat.)

About the Cospas-Sarsat Search and Rescue System

Orbiting high overhead every minute of the day is a worldwide network of polar-orbiting and geostationary satellites. Together with Russia’s Cospas spacecraft, they make up the high-tech international Search and Rescue Satellite-Aided Tracking System known as Cospas-Sarsat.

Cospas-Sarsat has been credited with nearly 30,000 rescues worldwide. The system relies on signals received on the 406 MHz frequency to pinpoint position and speed rescuers to the scene of an emergency on land or at sea.

In fact, the more reliable, digital 406 MHz frequency has become the de facto internationally recognized distress frequency. Using the 406 MHz frequency, modern signaling devices can quickly beam GPS LAT/LON coordinates to orbiting satellites. This frequency also allows a position fix through Doppler shift to acquire a location even when GPS can’t.

As of February 1, 2009, satellite processing of distress signals from the older 121.5 and 243 MHz emergency beacons was terminated worldwide due to unreliability and false alarms. When a 406 MHz beacon signal is received, search and rescue personnel can retrieve information from a registration database.

This includes the beacon owner’s contact information, emergency contact information and details regarding the specific trip plan and any medical conditions of the owner or members in the party. Having this information allows the Coast Guard, or other rescue personnel, to respond appropriately. NOAA, along with the U.S. Coast Guard, is strongly advising all mariners, aviators and individuals using 121.5/243 MHz emergency beacons to make the switch to 406 MHz in order to take full advantage of the Sarsat system.

Cospas-Sarsat is maintained and operated by governments all over the world, thus there is no subscription fee required for owning a 406 MHz EPIRB, ELT or Personal Locator Beacon.

Tags: Cospas Sarsat, 406 MHz Rescue, Search and Rescue Process, Coast Guard Rescue, How a rescue works, Anatomy of a rescue, EPIRB, Emergency Position Indicating Radio Beacon, Personal Locator Beacon, PLB, Emergency Locator Transmitter, ELT

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ACR Employee Celebrates 30-year Anniversary!


On Friday, March 1, 2013, one of our most dedicated employees celebrated her 30-year anniversary with ACR. Hired in 1983, Wilhemina Jackson began her ACR career as an Assembler where she worked to assemble mechanical items used in the production of our products. Wilhemina now works in our Rework department where she repairs PC boards, assists in the production of fixtures, builds batteries, and helps with some of the products sent in for repair.

When asked about the most rewarding part of her job, Wilhemina says she enjoys being able to make products that help save people’s lives.

Wilhemina lives close to our facility in Hollywood, Florida. She has two grown children and one granddaughter. Walking and spending quality time with her family are among her top interests outside of work.

In the past 30 years, Wilhemina has seen a lot of changes at ACR. She says our way of doing things and the products we make have changed quite a bit, especially in the last 10-15 years.

While a lot has changed at ACR in the last 30 years, one thing that has not changed is our undying committment to producing quality products that save lives. Congratulations Wilhemina!

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FORT LAUDERDALE, FL-ACR/ARTEX is pleased to share that an unnamed Boy Scout chaperon was saved by a fellow chaperone’s use of a ResQLink Personal Locator Beacon (PLB).
Ten Boy Scouts and five adults set out on seven canoes for a 68-mile trip on the Colorado River. They docked for camp at Carrizo Campgrounds. Not long after setting up camp, one of the chaperons became recognizably ill. It quickly became evident that assistance from the paramedics was necessary.
Jeff Murdock, fellow Boy Scout chaperon tried various communication devices the troop had with them; communication devices ranging from cell phones to a marine radio to a hand radio. All of the attempted communication methods failed. The closest cell tower was 16 miles away.
Jeff then activated his ResQLink Personal Locator Beacon (PLB). Moments after he pushed the emergency button, his GPS position was determined and the satellite distress signal was sent to the US Air Force National Rescue Coordination Center with his coordinates. Help was soon on the way. “If we didn’t have that beacon, there would have been a very different outcome. With all that emergency equipment I had on me, it didn’t matter. It’s that beacon that worked,” said Jeff Murdock; San Diego, CA.

Jeff’s wife (his registered contact for the PLB) was notified by the La Paz County Sheriff’s Office that the PLB was activated. A ranger showed up on the camp site where Jeff and the patient were present, as soon as she could. Once the ranger was made aware of the severity of the call, she immediately requested a helicopter for medevac. A helicopter landed soon after the call was made and took the patient to the nearest medical facility for care. After care and treatment, the patient was stabilized and was sent home a couple of days later. He is safe and sound today.

ACR/ARTEX learned of Jeff’s story this past week and welcomed him to Survivor Club, this gives Jeff and all of our survivors the opportunity to share their story. These first-hand accounts educate fellow outdoor enthusiasts on the lifesaving advantage of carrying a distress beacon. Read Jeff’s survivor stories and others at: