Which frequency and emission is used for aircraft distress communications?

The frequency 121.500 MHz is designated as the international distress frequency for aircraft, specifically for emergencies. This frequency is monitored continuously by air traffic control and is accessible to all aircraft in the vicinity for emergency communications. The emission type A3E refers to amplitude modulation of the carrier signal, which is appropriate for voice communications, particularly in distress situations where clear voice communication is paramount.

This combination of frequency and emission type is critical because it facilitates immediate response from other aircraft or ground units when a distress call is made. The clear distinction that A3E denotes voice communications is essential in emergencies for conveying urgent messages swiftly and accurately.

Other choices may include frequencies or emissions that are not standardized for distress communications in aviation, making them unsuitable for such critical situations.