Tuesday, March 03 2015 21:56

The ABCs of ELTs

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A clear understanding of FAR 91.207 is just the beginning for pilots looking at installing a new ELT.

March 2015-

“ELTs are specialized radio transmitters that sit in the aircraft and are designed to do nothing,” says Joan Goodman, president of Emergency Beacon Corp. based in New Rochelle, N.Y. “And they should do nothing—that is, they are designed not to interfere [with other equipment].”
That is, until they’re needed. “In the event of an incident, the ELT will either trigger automatically, or can be manually activated,” Goodman explained. Automatic ELTs begin transmitting an emergency distress signal only after a significant change in velocity of the aircraft.
There are a number of companies that make 406 MHz ELTs for use in the United States. These include ACK, ACR/Artex, Ameri-King, Emergency Beacon Corp., Emerging Lifesaving Technologies and Kannad.

Factors in the price
A 406 MHz ELT can be costly, and there are several reasons why. First, the parts play a big role. “The signal is so specific and so narrow, you need a very specific oscillator—and it’s very expensive,” Goodman told me. “If the price of the oscillator came down, prices on ELTs would come down.”
The testing process is also a factor in the final price. These devices are built to withstand a lot, and their critical electronics—which Goodman says are “quite small, actually”—need to be well protected. Emergency Beacon’s units house these potentially lifesaving electronics under closed-cell polyurethane.
Because a certified ELT is required to put out a five-watt burst signal and transmit on 406 MHz for 24 hours and at 121.5 for 48 hours, it also has to have a good power source.“There’s only one [element] that’ll do that: lithium,” said Goodman. And lithium batteries can be pricey.
The inclusion of GPS technology can also drive up the price of an ELT. GPS allows greater detail, but at a significant cost. Emergency Beacon Corp. doesn’t offer GPS-enhanced ELTs right now—the technology adds both cost and complication, Goodman says. “The information [already] provided by the satellites will get a rescuer so close that they can typically walk to the site,” she explained.

Regulations and proposed changes
The last six years have brought many changes. In February 2009, COSPAS-SARSAT stopped processing signals from 121.5 MHz ELTs, so these devices are no longer satellite-detectable. TSO-C91a, the TSO that mandated the performance standards for the 121.5 equipment, was canceled effective Dec. 1, 2012.
According to the Federal Register, “Manufacturers applying for new ELT technical standard order authorizations after December 1, 2012 must use TSO-C126a, or a subsequent ELT technical standard order.”
In the notice of cancellation for TSO-91a published in May 2012, the FAA determined the following benefits to the new TSO:
TSO-C126a ELT equipment is more accurate and reliable than the 121.5 MHz ELT equipment. Examples of these improvements are: (1) Global satellite coverage; (2) a unique beacon identification which is required to be registered so that if an alert is activated the rescue coordination center can confirm whether the distress is real, who they are looking for, and where the search should begin; (3) 406 MHz ELTs can be received by geostationary satellites which are always visible and provide instantaneous alerting, and (4) increased position accuracy which reduces the search area to less than two nautical miles in radius. Additionally, 406 MHz ELTs can optionally include a GPS position which can potentially reduce the search area to within 100 meters of the accident site.
The next iteration of this order, TSO-C126b with an effective date of Nov. 26, 2012, spells out the current minimum performance standards that affect all new applications for 406 MHz ELTs.
And more improvements to ELTs are coming, Goodman said. “There will be changes,” she explained. “They’re talking about enhancements.” The RTCA, the Radio Technical Commission for Aeronautics, has formed a special committee (SC 229) and the outcome will likely result in a second-generation of ELTs. (See the sidebar on page 28. —Ed.) But exactly when those changes will occur is anyone’s guess right now.

Consider these things
before purchasing
There are six general types of ELTs, but the two that General Aviation pilots are most familiar with are the automatic fixed (AF) and automatic portable (AP) ELTs. If you’re in the market for a new 406 MHz ELT, you have a lot of options—just make sure the unit you choose is FAA approved and supported by COSPAS-SARSAT.
The first decision owner-pilots will need to make is where to they’d like the ELT is to be mounted: in the tail, or in the cabin. Automatic portable ELTs can be installed in the cabin, while automatic fixed ELTs are installed in the tail. Both have pros and cons.
An aft mounted ELT is a more involved installation—you’re paying to have someone climb into the tail of the airplane, after all. The device requires a permanently mounted external antenna and uses more cable (which also adds to the expense). Aft-mounted ELTs require a remote monitor, which has three settings: on, off and standby.
A cabin-mounted automatic portable ELT is a simpler installation, and its external antenna can be detached in an emergency. You also won’t have to crawl into the tail when it’s time to do the periodic inspections or change the battery.
Whether you fly a high-wing or a low-wing, it’s mostly a personal choice as to where to install the ELT. However, Goodman says, “[the owner of] an amphibious aircraft may wish to have the ELT in the tail, while a bush pilot may wish to be able to put their hand on it easily.”
Goodman further states, “The language [in FAR 91.207] that ‘fixed and deployable automatic type transmitters must be attached to the airplane as far aft as practicable’ can be confusing for some people. Many believe the mandate is that it must be in the tail [of the aircraft]—but portable is legal,” she said.
“You of course can have [the ELT] in the tail, but you might want it as close to the pilot as possible—so when you land, it’s right behind the pilot seat,” she added.

The registration process
“When you buy an ELT it’s a rule that you register it. In the United States, that registration body is NOAA,” Goodman explained. A unique digital ID code—called a Unique Identifier Number, or UIN—is assigned at the factory. This 15-digit code is printed on the device’s exterior, and you need to have it handy in order to complete your registration.
In addition to the UIN, information you’ll need to supply includes your name and address, the aircraft’s N-number, colors, type, home base and—this is very important—at least one phone number where the owner/pilot can be reached, along with emergency contact information.

Activation protocol
When an ELT is activated, the signal goes up to the letter satellites (COSPAS-SARSAT), the weather satellites, letter receivers and transmitters. COSPAS-SARSAT is responsible for the narrowing of the signal and maintaining the specs.
When the signal comes back from the satellites, it goes to a Local User Terminal (LUT). The LUT sends the information to the Rescue Coordination Center (RCC). For ELTs and PLBs, this is the Air Force RCC. (For more information on how the search and rescue response is organized, see the link in Resources. —Ed.)
For these centers to work efficiently, they need to access your personal information as well as airport information. Goodman says an easy first step when an ELT activates is for the responding agency to “call the damn phone number!”—that is, the one you listed when you registered your device. Make sure your personal information is current so any attempts to reach you can happen quickly.
Often the first questions by the LUT will include things like, “Is the plane there?” “If not, where is it?” “When did it leave?” “Is there a flight plan?”
These simple acts can go a long way toward mitigating expense if an ELT was inadvertently triggered. In the event of an accidental activation, NOAA asks that you immediately cancel the search effort by contacting the Air Force RCC at 1-800-851-3051.
Assuming a rescue effort is legitimate, the RCC will gather as much information as it can and then coordinate the response. These responding agencies can include the National Guard, the Air Force (including the Civil Air Patrol), that state’s police (each state police has a rescue function) and possibly even the Boy Scouts.

Inspection and compliance
FAR 91.207 requires inspection of an ELT every 12 months. This action is to check four things: that the ELT is properly installed; that it doesn’t have corrosion in the battery; that the controls and crash sensor are operable; and that the antenna has a sufficient signal. Make sure you understand FAR 91.207 and how it applies to your aircraft operations.
Finally, if the battery in your ELT is more than five years old, you are required to change it. Lithium is a hazardous material, so make sure to dispose of it according to the regulations in your area.
Be sure the new battery is approved for the device or you’ll void your warranty. An approved replacement battery pack generally costs anywhere from $189 and $239, according to Goodman.

Preventive maintenance
In addition to the inspection points in FAR 91.207, Goodman recommends you regularly check the mounting bracket for corrosion in the screws and fastener and also check the connectors on the bottom of the ELT and bracket. Is everything nice and clean? Does the on/off switch appear clean?
Check carefully for corrosion or damage in an aft-mounted ELT; this can easily occur if someone were to wash the well. And it might be a good idea to inspect the unit after any service actions are performed in the vicinity of the mount: Goodman told me a story about one ELT that been contaminated with conductive grease, rendering it completely inop.
Also, keep track of your antennas! All ELTs ship with auxiliary antennas for use outside the aircraft, and lot of people lose or misplace them. Also, it’s not uncommon for an inexperienced installer to place the antenna in sideways or upside down—so double-check that the signal is sufficient.
If you need a replacement part for your ELT, Goodman reports that parts are usually available. “Some repairs are easily done in the field—an antenna, for example—but some [ELTs] have to come back in,” she said. This would include any time the electronics need to be accessed.
“Malfunctions are fairly unusual,” Goodman said. “We build on the belief—as do all of the manufacturers—this equipment has to work.” Emergency Beacon Corp. does not sell used equipment and doesn’t recommend its use.
In the rare instance that an ELT requires service, ask the manufacturer if they’ll reissue a warranty. In the case of Emergency Beacon Corp. equipment, “if we repair it, it’s factory-new,” Goodman said. “This includes a [new] two-year warranty.”

Heather Skumatz is managing editor for Piper Flyer. Send questions or comments to This email address is being protected from spambots. You need JavaScript enabled to view it..


Further information
NOAA Search and Rescue
Satellite Aided Tracking
Rescue Coordination Centers

AIM Chapter 6, Section 2
“Emergency Services available to pilots”

Technical documents
Advisory Circular 43.13-1B, CHG 1

FAR 91.207

TSO C126b

ELT manufacturer & PFA supporter
Emergency Beacon Corp.

Other ELT manufacturers

ACK Technologies, Inc.

Ameri-King Corp.

Emerging Lifesaving Technologies

Kannad Aviation

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