Definition
A failure or degraded condition in one or more components of an electronic flight display (EFD) system, in which the primary flight display, multi-function display, or the sensors and computers feeding them no longer present accurate, complete, or reliable flight information. Malfunctions can range from the loss of a single piece of data (such as airspeed or attitude) to a full screen failure, and may be flagged by the system with warning indications, red Xs over affected data, or comparator alerts between independent sources.
Plain English
Something has gone wrong with one of the glass cockpit screens, or with the equipment feeding information to it, so the pilot can no longer trust what it shows -- or part of it has gone blank.
Context Anchor
Seen in instrument flying and glass-cockpit training, especially when a pilot must recognize a bad display and use backup instruments or another available source of flight information.
Derivation
Electronic flight display refers to the screens that replaced traditional round-dial instruments. Malfunction comes from Latin male (badly) and functio (performance) -- literally, performing badly. Together: the screens, or the systems behind them, are not performing as they should.
Why Pilots Care
Loss of primary flight information can quickly lead to disorientation in instrument conditions unless the pilot immediately transitions to backup instruments or partial-panel techniques.
Analogy
It is like a car dashboard screen that still lights up but shows the wrong speed or freezes on old information. The screen is present, but you should not trust it without checking another source.
Grounding Statement
The key point is not whether the screen is dark; the key point is whether the flight information can still be trusted.
Intuition Check
Do not assume a malfunction means the display has gone completely blank. A display can malfunction while still showing information, if that information is wrong, frozen, incomplete, or unreliable.
Example Sentence 1
When the attitude indicator on the primary flight display showed a red X, the pilot recognized an electronic flight display malfunction and transitioned to the standby attitude indicator.
Example Sentence 2
Training requires immediate cross-check of standby instruments following any electronic flight display malfunction.