Radio Failure Procedures: Maintaining Safety Without Communication

Complete failure (neither transmit nor receive) is the most challenging. You set squawk 7600 and maintain heading and altitude. Do not deviate from your filed flight plan. ATC will see your radar target and know your intention from your flight plan. They will clear traffic accordingly.

If you are in controlled airspace (Class C, Class D, Class E with IFR traffic) and complete radio failure occurs:

Immediately set squawk 7600.
Maintain your last assigned altitude and heading.
If you must deviate (e.g., weather, terrain), do so and descend slowly while watching radar for nearby traffic (if equipped with traffic awareness systems).
Proceed to your destination aerodrome if it is in controlled airspace, or divert to the nearest larger aerodrome where ATC can direct you visually.
Monitor your destination aerodrome frequency on a backup radio if available (many aircraft have a second COM radio).

If you are in uncontrolled airspace (Class G airspace without active radio service):

Set squawk 7600.
Maintain your planned altitude and track.
Proceed to your destination, or if that is impossible, divert to the nearest suitable aerodrome.
You may land at the nearest suitable aerodrome, even if it is not your planned destination.

The definition of "suitable aerodrome" is: within glide distance, with adequate runway length, with no hazards you cannot avoid, and preferably with someone on the ground who can assist.