Definition
Failures or degraded performance of the radio communication equipment (such as VHF radios used to talk with ATC) or the navigation equipment (such as VOR, GPS, ILS, or transponder) installed in the aircraft. A malfunction may be a complete loss of the equipment, a partial loss, or erroneous indications that cannot be trusted.
Plain English
When the radios you use to talk to controllers, or the equipment you use to find your way, stop working properly — either fully, partially, or by giving wrong information.
Context Anchor
Seen in instrument flying discussions, especially when a pilot must recognize and manage unreliable radios, navigation equipment, antennas, or cockpit displays.
Derivation
“Communication” comes from a Latin word meaning “to share.” “Navigation” comes from older words meaning “ship” and “to direct or steer.” “Malfunction” combines “mal,” meaning “bad” or “wrong,” with “function,” meaning “work.” Together, the phrase means the equipment for sharing information or finding the way is not working correctly.
Why Pilots Care
Loss of these systems removes critical ATC instructions and position data, forcing immediate use of backup procedures to maintain safety.
Intuition Check
Do not assume a malfunction means the equipment is completely dead. A malfunction can also mean the system is working partly, giving unreliable information, or acting in a way the pilot did not expect.
Example Sentence 1
After takeoff into the clouds, the pilot noticed a communication/navigation system malfunction when the primary radio went silent and the course needle drifted off-center.
Example Sentence 2
Preflight revealed communication/navigation system malfunctions that required maintenance before the IFR departure.