As of mid-2012, the National Oceanic and Atmospheric Administration's (NOAA) Satellite Operations Center in Suitland, Md., had about 355,000 of the newer 406 MHz emergency beacons registered in its SARSAT database. Each 406 ELT transmits a unique identifier that can be looked up in the database to help determine who's in trouble.
SARSAT stands for Search And Rescue Satellite-Aided Tracking. About 62,800 of the registered 355,000 beacons were digital ELTs designed for use on aircraft. Most of the others were personal beacons, such as might be carried when hiking or camping. The FAA's aircraft registry lists about 350,000 aircraft, though perhaps not all are active.
The numbers make it clear that aircraft owners haven't rushed to replace their old ELTs that transmit on 121.5 MHz and the military's 243.0 MHz, even though it has been a couple of years since satellite monitoring of 121.5 ended.
SARSAT was developed by the U.S., Canada and France, and merged with a Russian system to create COSPAS-SARSAT, which operates around the world with 77 ground stations and 30 mission control centers. COSPAS is the acronym for a group of Russian words that translate as "space system for the search of vessels in distress."
The AFRCC (Air Force Rescue Coordination Center) is charged with the management of federal search-and-rescue activities in the contiguous 48 states and providing assistance when the point of focus is in Mexico or Canada. Located at Tyndall Air Force Base in Florida, AFRCC works closely with the Coast Guard, Civil Air Patrol and others.
AFRCC receives satellite tracking information, is notified by the FAA of overdue aircraft, maintains a computer system with resource files of available assets and generally decides who to send where. In 2011, AFRCC launched 73 search-and-rescue missions involving aircraft, resulting in 12 lives being saved. Overall in 2011, there were 866 missions of all types resulting in 245 lives saved.
The NTSB is among those convinced that the new ELTs help and said so in its October 2012 report on the crash of an Aero Commander 114 at Lander, Wyo., in which the pilot and both passengers were killed. The non-instrument pilot flew into instrument conditions and struck terrain. Even though it's doubtful the accident was survivable, the NTSB said a 406 MHz ELT would have helped search crews find the wreckage much sooner. An estimated 28 hours after the crash, the airplane's 121.5 MHz ELT signal was picked up and reported by a passing airliner. It took another 24 hours for the wreckage to be located by search personnel on a ridge at an elevation of 11,700 feet MSL.
When the Safety Board staged a two-day forum on general aviation search-and-rescue operations in July 2012, Chairwoman Deborah A. P. Hersman declared, "We are spending billions of dollars on new satellites, beacons and NextGen. Yet, we continue to see a high percentage of false alerts, and worse, aviation crashes where aircraft have not been found. And, we see aircraft owners who are passing their father's technology to their children."
At the foundation of advanced search and rescue is the 406 MHz beacon and satellite system. The precise frequency is 406.028 MHz. As of February 1, 2009, satellite monitoring of emergency frequency 121.5 MHz was ended, although 121.5 still is monitored by FAA facilities and in aircraft when feasible, and can be used by search-and-rescue assets. Older ELTs that are approved under TSO-91a transmit on 121.5 and the military frequency of 243.0 MHz.
Newer ELTs complying with TSO-C126 still operate on 121.5 in addition to 406.028. Military models can use 121.5, 406.028 and 243.0. The newer satellite system provides for faster recognition of ELT signals and greater accuracy in determining their location. As far back as September 2007, the NTSB issued a safety recommendation to the FAA calling for the agency to seek Congressional authority to mandate replacing all old ELTs with the then-emerging 406 MHz variety.
One of the speakers at the NTSB's forum was Joan Goodman, President of Emergency Beacon Corp., in New Rochelle, N.Y. They manufacture ELTs for both military and civilian use in portable cabin-mounted as well as fixed-installation models. She told me that the military seems better attuned to the value of the improved satellite system than the civilian pilot population because the Pentagon mandated that all of its aircraft carry a digital ELT. Goodman suggested, "As costs come down, there will be a change in civilian consumer attitude."
Goodman told the NTSB forum that improper installation can defeat technology. "ELTs need to be installed in or on a rigid area—not attached to the back of a seat or to the soft fabric on the wall of an aircraft. An ELT approved as an automatic fixed (AF) transmitter should be installed as far back in the craft as possible, usually in the tail or baggage area. AF transmitters need a remote control unit in the panel to make it convenient for the pilot to test the unit and reset after testing," Goodman said.
The digital 406 MHz units need to be connected to an antenna mounted on the aircraft's surface, but also come with an auxiliary antenna that can be plugged directly into the device for use if the external antenna is disconnected accidentally, or if the ELT is removed for use outside the aircraft.
Goodman explained to the NTSB forum that incorrect antenna placement can defeat proper ELT operation. She said, "Antennas need a ground plane, and ideally, the cable should not cross a breakpoint in the aircraft's structure. There are many reported cases of antennas being torn off the craft in an emergency or the cable being pulled out of either the transmitter or antenna. An aircraft that comes down inverted will often either break or bury the external antenna."
The lack of an external ELT antenna on an older ELT was cited in the NTSB's report on the crash of a Maule M-5-235C near Springville, Calif. The airplane hit trees at the 8,300-foot level of a mountain. The aircraft was owned and operated by the pilot and was on a personal sightseeing flight in the Sierra Nevada Mountains. Based on witness and National Weather Service observations along the route of flight, visual meteorological conditions prevailed with generally clear skies and light wind conditions.
The private pilot received serious injuries, while both passengers were killed. The flight originated at Long Beach, Calif., on the day of the accident and made stops at the California City and Kernville, Calif., airports.
Twelve days after the accident, the pilot of the aircraft walked into a cafe in the town of Olancha in the Owens Valley. After having something to eat and phoning relatives, the pilot contacted the Inyo County Sheriff's Department, reported that he was involved in an aircraft accident in the mountains and that his two passengers were still at the aircraft.
A sheriff's deputy and a pilot took the accident pilot on a flight to find the accident site by retracing the route the pilot said he walked along to reach the cafe. This attempt was unsuccessful. The pilot was next flown down to the area of the Kernville Airport, and he was able to orient himself and retrace the accident flight up the Kern River Valley to the crash site. A U.S. Navy helicopter responded to the crash site and found both passengers dead.
Investigators noted that while documents showed a portable ELT was installed in the aircraft, a fixed ELT by a different manufacturer was found in the wreckage. Both ELTs were approved for installation in the airframe under the type certificate. No documentation was found dealing with the removal of the factory-supplied ELT and the installation of the different ELT.
The unit, which was found in the wreckage, was mounted under the left front seat. According to installation instructions, a coaxial antenna cable was supposed to be routed under the carpet to the left front door post, then up the post to the left wing root and to the external antenna. The external antenna was supposed to be mounted on the metal wing root fairing.
After recovery of the aircraft, the airframe was examined for evidence of the external ELT antenna installation under the approved Maule type certificate drawings. No evidence of a coaxial cable installation was found. Furthermore, the wing root fairings showed no evidence that an external antenna had ever been mounted there. The ELT switch was found in the "off" position.
The pilot told investigators that he was flying at 12,000 feet MSL over the high terrain and, when nearing the accident site, the aircraft suddenly rolled and yawed to the right in very strong turbulence. The pilot said he had the impression that the aircraft was being pushed forward and down toward the ground by some strong force.
With the aircraft descending, the pilot managed to resume level flight just before hitting the trees. The NTSB determined that the probable cause of the accident was the pilot's entry into a box canyon at an altitude insufficient to maintain clearance from the surrounding terrain and obstacles. Factors in the accident were the high-density altitude and the steep, rapidly rising nature of the mountainous terrain.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other news concerning the National Transportation Safety Board.