Radio equipment and avionics operation
This section covers radio equipment and avionics operation: correct use of the VHF communications radio, transponder, intercom and emergency equipment, and the preflight checks that prevent avoidable communication failures.
Core rules
- The VHF communications radio has active and standby frequency displays. Select the next frequency on standby, confirm it, then transfer it to active; this reduces the risk of losing the assigned frequency.
- Set volume and squelch so that weak but readable transmissions are heard without excessive background noise. A squelch set too high can block a distant station.
- Use the push-to-talk switch correctly: pause, press, speak, release. A stuck microphone blocks the frequency and may require switching to another radio.
- The transponder should be set to the assigned code and Mode C as required; confirm the display after selection.
- Know the emergency equipment: the ELT transmits on 121.5 MHz (and 406 MHz for modern units), and a handheld or second radio may provide backup.
Worked example
A pilot is assigned 124.700. The pilot selects 124.700 on standby, confirms the digits, transfers it to active, listens briefly, then transmits: “Lagos Approach, 5N-ABC, 124.700.” Confirming the frequency before transmitting prevents calling on the wrong channel and missing the controller’s reply.
Traps
Leaving the emergency frequency selected after use; not checking the intercom or headset; transmitting with a stuck microphone; and assuming a frequency is correct without confirming the display.