Definition
A memory aid used in northern hemisphere flying to recall how a magnetic compass behaves during changes in airspeed on an east or west heading. When the aircraft accelerates while heading east or west, the compass momentarily indicates a turn toward the north. When it decelerates, the compass indicates a turn toward the south. The actual heading has not changed; only the compass reading is temporarily in error.
Plain English
ANDS is a quick way to remember that speeding up makes the compass swing toward north, and slowing down makes it swing toward south, when you are flying east or west. The compass is wrong for a moment, not the airplane.
Context Anchor
Used in flight training when learning magnetic compass errors, especially during instrument training and basic attitude instrument flying.
Derivation
ANDS is built from the first letters of the memory phrase “Accelerate North, Decelerate South.” The letters help the pilot remember which way the compass will falsely swing during a speed change.
Why Pilots Care
Prevents pilots from misreading the compass and making incorrect heading corrections during airspeed changes.
Intuition Check
ANDS is not a command to turn north or south. It describes the false direction the magnetic compass may show during a speed change.
Example Sentence 1
Flying west on a partial-panel exercise, the instructor reminded the student of ANDS so she would not chase the compass when she added power.
Example Sentence 2
The instructor reminded the student to apply ANDS when decelerating on a southerly heading so the compass indication would be interpreted correctly.