4/20/23 

AIM 

MHz ELT alerts. Compared to the almost instantaneous detection of a 406 MHz ELT, SAR forces’ normal 

practice is to wait for 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. Therefore, due to the obvious advantages of 406 MHz beacons and 

the significant disadvantages to the older 121.5/243.0 MHz beacons, and considering that the International 

Cospas

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Sarsat Program stopped the monitoring of 121.5/243.0 MHz by satellites on February 1, 2009, all aircraft 

owners/operators are highly encouraged by both NOAA and the FAA to consider making the switch to a digital 

406 MHz ELT beacon.  Further, for non

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aircraft owner pilots, check the ELT installed in the aircraft you are 

flying, and as appropriate, obtain a personal locator beacon transmitting on 406 MHz. 

b.  Testing. 

1. 

ELTs should be tested in accordance with the manufacturer’s instructions, preferably in a shielded or 

screened room or specially designed test container to prevent the broadcast of signals which could trigger a false 

alert. 

2. 

When this cannot be done, aircraft operational testing is authorized as follows: 

(a) 

Analog 121.5/243 MHz ELTs should only be tested during the first 5 minutes after any hour. If 

operational tests must be made outside of this period, they should be coordinated with the nearest FAA Control 

Tower. Tests should be no longer than three audible sweeps. If the antenna is removable, a dummy load should 

be substituted during test procedures. 

(b) 

Digital 406 MHz ELTs should only be tested in accordance with the unit’s manufacturer’s 

instructions. 

(c) 

Airborne tests are not authorized. 

c.  False Alarms. 

1. 

Caution should be exercised to prevent the inadvertent activation of ELTs in the air or while they are being 

handled on the ground. Accidental or unauthorized activation will generate an emergency signal that cannot be 

distinguished from the real thing, leading to expensive and frustrating searches. A false ELT signal could also 

interfere with genuine emergency transmissions and hinder or prevent the timely location of crash sites. Frequent 

false alarms could also result in complacency and decrease the vigorous reaction that must be attached to all ELT 

signals. 

2. 

Numerous cases of inadvertent activation have occurred as a result of aerobatics, hard landings, 

movement by ground crews and aircraft maintenance. These false alarms can be minimized by monitoring 121.5 

MHz and/or 243.0 MHz as follows: 

(a) 

In flight when a receiver is available. 

(b) 

Before engine shut down at the end of each flight. 

(c) 

When the ELT is handled during installation or maintenance. 

(d) 

When maintenance is being performed near the ELT. 

(e) 

When a ground crew moves the aircraft. 

(f) 

If an ELT signal is heard, turn off the aircraft’s ELT to determine if it is transmitting. If it has been 

activated, maintenance might be required before the unit is returned to the “ARMED” position. You should 

contact the nearest Air Traffic facility and notify it of the inadvertent activation. 

d.  Inflight Monitoring and Reporting. 

1. 

Pilots are encouraged to monitor 121.5 MHz and/or 243.0 MHz while inflight to assist in identifying 

possible emergency ELT transmissions. On receiving a signal, report the following information to the nearest 

air traffic facility: 

Emergency Services Available to Pilots 

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