Definition 1 of 2
Plain English Meaning
A device that stops the pilot from seeing outside, so they can practise flying using only the instruments — even though it is actually a clear day.
Full Definition
A training tool worn or positioned on the pilot to block the view outside the cockpit while leaving the flight instruments visible, used to simulate instrument meteorological conditions during training and practical tests when the actual weather is clear.
Context Anchor
Seen in instrument training, including practice for instrument takeoffs and other exercises where the pilot must rely on the aircraft’s instruments instead of outside cues.
Derivation
Plainly named: a device that limits the pilot's view. The name describes exactly what it does — restrict outside vision so the pilot must rely on instruments.