Definition
A phrase used in ATC clearances and instructions meaning that the pilot must establish two-way radio communication with the specified ATC facility, on the assigned frequency, at the point or time indicated. It is the pilot's responsibility to make the call; ATC will not initiate it.
Plain English
When ATC tells you contact is required, you are the one who has to call them on the radio at the right place or time. They are not going to call you first.
Context Anchor
Seen in AIM glossary discussions of outer areas and Class C communication requirements.
Derivation
Radio comes from a word meaning a ray or spoke, which fits how radio signals spread outward. Contact comes from a word meaning touching; in radio use, it means the aircraft and ATC have made a real communication connection, not physical contact.
Why Pilots Care
Failure to establish the required contact can result in airspace violations, loss of separation services, or unsafe flight in high-traffic environments.
Analogy
It is like making a phone call: dialing the number is not the same as having a conversation. You know contact has been made when the other person answers you directly.
Intuition Check
Do not assume radio contact means the pilot has transmitted. It means ATC has answered in a way that shows two-way communication with that aircraft has been established.
Example Sentence 1
After takeoff, the tower instructed the pilot to contact Departure on 119.4, satisfying the radio contact required of the pilot.
Example Sentence 2
The radio contact required of the pilot allows ATC to issue traffic advisories and sequencing instructions for the landing airport.