Story and also Photo by H. Dean ChamberlainReprinted with permission indigenous FAA Aviation News


FAA regulations, title 14 password of federal Regulations section 91.207(d)(4), calls for that an plane emergency locator transmitter (ELT) it is in tested yearly for "the existence of a sufficient signal radiated indigenous its antenna." The Aeronautical info Manual (AIM) in chapter 6, ar 6-2-5, discusses ELTs, your use, and how to check them. To paraphrase a statement from a movie around a failed pilgrimage to the Moon, "Folks, we have a problem." The FAA needs an ELT radiated test, yet if the check is not done properly, the Federal communications Commission (FCC) could take enforcement action against the person doing a 406 MHz ELT test.

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Here is the problem. As soon as the FAA test requirements were written, the straightforward ELT was an analog 121.5MHz unit transmitting in the aeronautical frequency band. If the ELT gift tested might not be isolated in ~ an approved radio frequency shielded room or container, which keeps the signal from going beyond the room or container, a radiated test can be done within the first five minute after the hour. The test requirements noted the variety of recommended sweeps of the signal to minimize the threat of anyone reasoning the check signal was an really distress alert. The human doing the check would conveniently activate the ELT, hear for that distinctive sound top top a surrounding aeronautical band aircraft radio or hand held transceiver and also then rotate off the ELT.

This test method met the FAA requirement and also most establishments were okay v the idea. That was till the newer 406 MHz ELT distress beacon was developed. Part of the difficulty is that rather of gift in the aeronautical band, 406 MHz is a safeguarded international distress frequency. Plus, with a correctly registered 406MHz ELT, the sent signal consists of a digital code that can be offered to recognize the owner. As a result, the FCC deserve to track down anyone who, in the opinion, transmits a fraudulent or non-emergency distress signal, e.g. One FAA test.

Since most 406 MHz ELTs include a low-powered 121.5 MHz homing transmitter, the challenge for the human being doing the annual ELT check is just how to satisfy the FAA need without violating the FCC regulations. Since in most situations the human doing the trial and error has no way to screen the406 MHz emitted coded signal with-out one-of-a-kind equipment and can there-fore just listen for the activation that the121.5 MHz homing signal that the linked 406/121.5 MHz ELT.

Short that a adjust in the regulation, the adhering to is one means of conducting the test. Remember, the objective of check is to inspect the aircraft"s mounted system indigenous ELT transmitter to its antenna.

Anyone testing any type of ELT have to follow the manufacturer"s recommended procedures. If those actions are not obtainable and can not be found, the adhering to is one procedure that has been coordinated v the nationwide Oceanic and also Atmospheric management (NOAA) i beg your pardon operates the unified States part of the inter-national satellite-based search and rescue mechanism that monitors and processes distress beacon alerts.

Owners the 406 MHz ELTs should limit any kind of test to much less than 30 seconds. This will preclude the satellites native receiving a signal native the 406 MHz beacon once activated come the "ON" problem or switch place while trial and error the 121.5 MHz ELT portion of a linked ELT. This will protect against the government from initiating a search and also rescue action. There have been numerous reports of unintentional activation the the merged ELTs once periodic maintenance experimentation of the 121.5MHz signal is experiment to assure appropriate performance. Activating the "ON" function, i beg your pardon is part of the remote control panel fairly than gaining accessibility to the linked ELT and also activating the "TEST" function, has led come violations administered native the FCC and causes emergency responders to react in an effort to find a downed wait craft. If the an option to the "ON" place is minimized to 30seconds or less, over there is sufficient time protection to stop crossing the 50-second time threshold for activating the 406MHz locator signal. Operators have to advise their maintenance personnel that this limitation and possible vulnerability come violations or sanctions.

The adhering to are excerpts from AIM ar 6-2-5, Emergency Locator Transmitter (ELT), dealing with testing, false alarms, and reporting.


1. ELTs have to be tested in accordance through the manufacturer"s instructions. This must be done, preferably, in a shielded or screened room or specially designed test container to protect against the broadcast of signals, i m sorry could trigger a false alert.

2. As soon as this cannot be done, plane operational testing is authorized as follows:

(a)Analog 121.5/243 MHz ELTs need to only be tested throughout the first five minute after any type of hour. If work tests have to be made outside of this period, they have to be coordinated v the nearest FAA control Tower or flight Ser-vice Station. Tests have to be no longer than 3 audible weeps. If the antenna is removable, a dummy fill should it is in substituted throughout test procedures.

(b)Digital 406 MHz ELTs should only be tested in accordance v the unit"s manufacturer"s instructions.

(c) Airborne tests are not authorized.

False Alarms

1. Caution need to be exercised to avoid the inadvertent activation of ELTs in the wait or while they are being handled on the ground. Accidental or unauthorized activation will generate one emergency signal the cannot be differentiated from the genuine thing, causing expensive and also frustrating searches. A false ELT signal could also interfere with genuine emergency transmissions and also hinder or prevent the timely place of crash sites. Regular false alarms might also an outcome in complacency and also de-crease the vigorous reaction that have to be fastened to every ELT signals.

2. Numerous situations of inadvertent activation have arisen as a result of aerobatics, difficult landings, and also movement by ground crews, and also aircraft maintenance. This false alarms deserve to be reduced by monitoring121.5 MHz and/or 243.0 MHz together follows:

(a)In flight when a recipient is available.

(b) prior to engine shut down at the end of each flight.

(c) as soon as the ELT is handled throughout installation or maintenance.

(d) when maintenance is gift per-formed close to the ELT.

(e) once a ground crew move the aircraft.

(f) If an ELT signal is heard, rotate off the aircraft"s ELT to identify if the is transmitting. If it has been activated, maintenance could be required prior to the unit is went back to the "ARMED" position. Girlfriend should contact the nearest Air web traffic facility and also notify it of the inadvertent activation.

In trip Monitoring and also Reporting

1. Pilots are encouraged to monitor121.5 MHz and/or 243.0 MHz if in flight to help in identifying feasible emergency ELT transmissions. ~ above receiving a signal, report the adhering to information to the near-est air web traffic facility:

(a) Your place at the moment the signal was very first heard.

(b) Your place at the time the signal to be last heard.

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(c) Your position at best signal strength.

(d) Your flight altitudes and also frequency on which the emergency signal to be heard: 121.5 MHz or 243.0 MHz. If possible, positions must be offered relative come a navigation aid. If the aircraft has homing equipment, administer the bearing come the emergency signal with each re-ported position.