Definition
Failures or abnormal operation of one or more of an aircraft's onboard systems — such as the pitot-static system, electrical system, vacuum system, flight instruments, autopilot, or engine instrumentation — that affect the accuracy, reliability, or availability of information and controls the pilot relies on to fly the aircraft safely, particularly in instrument conditions.
Plain English
When something on the aircraft stops working properly. It could be an instrument giving wrong readings, a system losing power, or a piece of equipment failing outright. The pilot has to recognise it, work around it, and keep flying safely.
Context Anchor
Seen in instrument flying when a system fails, gives an abnormal indication, or no longer supports the pilot as expected during flight.
Derivation
‘Malfunction’ comes from the Latin ‘mal-’ meaning ‘bad’ or ‘wrongly,’ combined with ‘function,’ meaning ‘to perform.’ A malfunction is something performing badly or wrongly — not necessarily failing completely, just not doing its job correctly. That distinction matters in flying: a partial or misleading failure is often more dangerous than an obvious one.
Why Pilots Care
Recognizing and responding correctly prevents loss of control or disorientation when flying on instruments.
Grounding Statement
The key idea is abnormal operation, not necessarily total failure.
Intuition Check
Do not assume a malfunction always means a complete failure. In aviation, a malfunction can be partial, intermittent, or shown only by an unusual indication.
Example Sentence 1
The chapter on aircraft system malfunctions teaches pilots how to recognise a failed attitude indicator before it causes a loss of control.
Example Sentence 2
Preflight planning includes reviewing procedures for common aircraft system malfunctions that could occur in IMC.