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AIM

10/12/17

6−2−2

Emergency Services Available to Pilots

discretionary. The decision will depend on the

circumstances of the individual incident.

6−2−4. Emergency Locator Transmitter

(ELT)

a. General.

1. ELTs are required for most General Aviation

airplanes.

REFERENCE−

14 CFR SECTION 91.207.

2. ELTs of various types were developed as a

means of locating downed aircraft. These electronic,

battery operated transmitters operate on one of three

frequencies. These operating frequencies are

121.5 MHz, 243.0 MHz, and the newer 406 MHz.

ELTs operating on 121.5 MHz and 243.0 MHz are

analog devices. The newer 406 MHz ELT is a digital

transmitter that can be encoded with the owner’s

contact information or aircraft data. The latest

406 MHz ELT models can also be encoded with the

aircraft’s position data which can help SAR forces

locate the aircraft much more quickly after a crash.

The 406 MHz ELTs also transmits a stronger signal

when activated than the older 121.5 MHz ELTs.

(a) The Federal Communications Commis-

sion (FCC) requires 406 MHz ELTs be registered

with the National Oceanic and Atmospheric

Administration (NOAA) as outlined in the ELTs

documentation. The FAA’s 406 MHz ELT Technical

Standard Order (TSO) TSO−C126 also requires that

each 406 MHz ELT be registered with NOAA. The

reason is NOAA maintains the owner registration

database for U.S. registered 406 MHz alerting

devices, which includes ELTs. NOAA also operates

the United States’ portion of the Cospas−Sarsat

satellite distress alerting system designed to detect

activated ELTs and other distress alerting devices.

(b) In the event that a properly registered

406 MHz ELT activates, the Cospas−Sarsat satellite

system can decode the owner’s information and

provide that data to the appropriate search and

rescue (SAR) center. In the United States, NOAA

provides the alert data to the appropriate U.S. Air

Force Rescue Coordination Center (RCC) or U.S.

Coast Guard Rescue Coordination Center. That RCC

can then telephone or contact the owner to verify the

status of the aircraft. If the aircraft is safely secured

in a hangar, a costly ground or airborne search is

avoided. In the case of an inadvertent 406 MHz ELT

activation, the owner can deactivate the 406 MHz

ELT. If the 406 MHz ELT equipped aircraft is being

flown, the RCC can quickly activate a search.

406 MHz ELTs permit the Cospas−Sarsat satellite

system to narrow the search area to a more confined

area compared to that of a 121.5 MHz or 243.0 MHz

ELT. 406 MHz ELTs also include a low−power

121.5 MHz homing transmitter to aid searchers in

finding the aircraft in the terminal search phase.

(c) Each analog ELT emits a distinctive

downward swept audio tone on 121.5 MHz and

243.0 MHz.

(d) If “armed” and when subject to crash−

generated forces, ELTs are designed to automatically

activate and continuously emit their respective

signals, analog or digital. The transmitters will

operate continuously for at least 48 hours over a wide

temperature range. A properly installed, maintained,

and functioning ELT can expedite search and rescue

operations and save lives if it survives the crash and

is activated.

(e) Pilots and their passengers should know

how to activate the aircraft’s ELT if manual activation

is required. They should also be able to verify the

aircraft’s ELT is functioning and transmitting an alert

after a crash or manual activation.

(f) Because of the large number of 121.5 MHz

ELT false alerts and the lack of a quick means of

verifying the actual status of an activated 121.5 MHz

or 243.0 MHz analog ELT through an owner

registration database, U.S. SAR forces do not

respond as quickly to initial 121.5/243.0 MHz ELT

alerts as the SAR forces do to 406 MHz ELT alerts.

Compared to the almost instantaneous detection of a

406 MHz ELT, SAR forces’ normal practice is to wait

for either a confirmation of a 121.5/243.0 MHz alert

by additional satellite passes or through confirmation

of an overdue aircraft or similar notification. In some

cases, this confirmation process can take hours. SAR

forces can initiate a response to 406 MHz alerts in

minutes compared to the potential delay of hours for

a 121.5/243.0 MHz ELT.

3. The Cospas−Sarsat system has announced the

termination of satellite monitoring and reception of

the 121.5 MHz and 243.0 MHz frequencies in 2009.

The Cospas−Sarsat system will continue to monitor

the 406 MHz frequency. What this means for pilots is

that after the termination date, those aircraft with only