What is the emergency frequency used for aviation communication?

The emergency frequency used for aviation communication is 121.5 MHz. This frequency is designated globally for distress and emergency communications by aircraft, specifically for use in emergencies when pilots need to establish contact with air traffic control or other aircraft. It is monitored continuously by air traffic control facilities and is crucial for ensuring that pilots in distress can receive help swiftly.

The reason this is the correct choice is that 121.5 MHz is recognized as the international standard emergency frequency for aviation. Pilots are trained to switch to this frequency when they encounter emergencies, ensuring that they can communicate their situation effectively and coordinate rescue efforts.

In contrast, the other frequencies listed serve different purposes within aviation. For instance, 125.0 MHz is often used for non-towered airport communications, while 118.0 MHz typically designates standard communication frequencies for air traffic control in the VHF range. Meanwhile, 123.45 MHz is frequently used as a common traffic advisory frequency (CTAF) for pilots to announce their positions and intentions at non-towered airports.