chapter  7
3 ELT mounting requirements
Pages 2

Figure 7.3 ELT transmitter and modulator printed circuit board (the crystal oscillator is located on the right with the dual-frequency output stages on the left)

Figure 7.1 Type-W ELT with attachment cord secured by water-soluble tape (the antenna has been removed)

Figure 7.2 Interior view of the ELT shown in Figure 7.1. Note how the battery occupies approximately 50% of the internal volume

Figure 7.4 ELT test switch and test light (the antenna base connector is in the centre of the unit)

In order to safeguard the equipment and to ensure

that it is available for operation should the need

arise, various considerations should be observed

when placing and mounting an ELT and its

associated antenna system in an aircraft. The

following requirements apply to Type-F, AF, AP

ELT installations in fixed wing aircraft and


1. When installed in a fixed wing aircraft, ELT

should be mounted with its sensitive axis

pointing in the direction of flight

2. When installed in a rotorcraft ELT should be

mounted with its sensitive axis pointing

Table 7.2 Typical Type-AF ELT specification

Figure 7.5 Type-AF ELT control panel (note the three switch positions marked ON, ARMED and TEST/RESET)

approximately 45° downward from the

normal forward direction of flight

3. ELT should be installed to withstand

ultimate inertia forces of 10 g upward,

22.5 g downward, 45 g forward and 7.5 g


4. The location chosen for the ELT should be

sufficiently free from vibration to prevent

involuntary activation of the transmitter

5. ELT should be located and mounted so as to

minimise the probability of damage to the

transmitter and antenna by fire or crushing

as a result of a crash impact

6. ELT should be accessible for manual

activation and deactivation. If it is equipped

with an antenna for portable operation, the

ELT should be easily detachable from inside

the aircraft

7. The external surface of the aircraft should be

marked to indicate the location of the ELT

8. Where an ELT has provision for remote

operation it is important to ensure that

appropriate notices are displayed.