Definition
The short tick marks on the bank scale of an attitude indicator, located on either side of the index at the top of the instrument, used to show the angle of bank of the aircraft. On most attitude indicators the hash marks are positioned at 10°, 20°, 30°, 60°, and 90° of bank, with a longer mark at 45°.
Plain English
The little tick marks across the top of the attitude indicator that tell you how steeply the aircraft is banked left or right.
Context Anchor
Seen on cockpit instruments, especially the attitude display used to control and check bank during instrument flight.
Derivation
Hash mark' is a general English term for a short straight line used as a tally or scale mark. The name was carried over into instrument design because the marks function as a small graduated scale around the bank index.
Why Pilots Care
Precise alignment with these marks allows accurate bank control and standard-rate turns without outside visual references.
Analogy
Hash marks work like the small lines on a ruler. You do not need a number printed at every line; the marks still help you judge the amount.
Intuition Check
Do not read “hash marks” as damage, random scratches, or notes on the instrument. Here it means intentional reference lines used for measurement.
Example Sentence 1
Rolling into the turn, she stopped the bank pointer halfway between the second and third hash marks to hold about 25° of bank.
Example Sentence 2
During recovery from an unusual attitude, she used the hash marks to quickly return the wings to level.