What frequency would you attempt to contact on if you lost communication with ATC?

The appropriate frequency to contact in the event of a loss of communication with Air Traffic Control (ATC) is 121.5 MHz. This frequency is designated as the international emergency frequency for aircraft communications. It is monitored by ATC and is also utilized by search and rescue services, making it the most reliable option for emergency situations.

When pilots experience radio failure or other communication issues, they are instructed to switch to 121.5 to make distress calls. This frequency facilitates communication with other pilots and ground stations that may be able to assist in re-establishing contact or providing guidance.

While other frequencies are used for various purposes within aviation, they do not hold the same universal recognition and monitoring status as 121.5 MHz in emergency scenarios.