Definition
A procedure or checklist step that must be performed from memory, without delay and without first referring to a written checklist, in response to a critical in-flight situation such as an engine fire, engine failure on takeoff, or rapid depressurization.
Plain English
Something the pilot must do right away, from memory, before reaching for a checklist. The situation is too urgent to spend time reading.
Context Anchor
Seen in emergency procedures, abnormal procedures, aircraft checklists, and flight training scenarios.
Derivation
"Immediate" comes from Latin immediatus, meaning "without anything in between" -- in other words, no delay and no intermediate step. That fits the meaning here: the action happens right now, with nothing (including reading a checklist) coming between the event and the response.
Why Pilots Care
These memorized steps buy critical time and prevent further damage or loss of control before the pilot can safely reference the full checklist.
Intuition Check
Do not read this as just any action that happens soon. An Immediate Action Item is a specific required step that must be done first because delay matters.
Example Sentence 1
After the engine failure on takeoff, the pilot performed the immediate action items from memory before running the full emergency checklist.
Example Sentence 2
The student pilot recited the immediate action items for engine failure after takeoff during the preflight briefing.