Definition
Dip errors are inaccuracies in the magnetic compass caused by the vertical component of the Earth's magnetic field pulling the compass card downward toward the nearer magnetic pole. This vertical pull tilts the card during turns and during changes in airspeed, producing two specific errors: turning error (most pronounced when turning to or from north or south headings) and acceleration/deceleration error (most pronounced on east or west headings).
Plain English
The compass needle doesn't just point sideways toward the magnetic pole — it also gets tugged downward toward it. That downward tug makes the compass give wrong readings when the airplane banks in a turn or when it speeds up or slows down.
Context Anchor
Encountered when learning magnetic compass limitations, especially during turns and speed changes.
Derivation
Dip' here refers to the way the compass needle dips, or tilts downward, toward the Earth. Near the magnetic equator the needle stays roughly level; closer to the poles it tilts more steeply. This downward tilt is what causes the errors, which is why they are called dip errors.
Why Pilots Care
These errors produce large heading deviations during turns and speed changes, so pilots must apply specific corrections or cross-check other instruments to maintain accurate navigation.
Analogy
A compass affected by dip errors is like a hanging sign that is being pulled down on one side. It still points generally the right way, but the extra pull can make it swing or tilt and give a misleading indication for a moment.
Intuition Check
Do not read “dip” here as a small decrease in heading or altitude. In this context, “dip” means a downward magnetic pull inside the compass that can create a false direction indication.
Example Sentence 1
When rolling out of a turn onto a north heading, the pilot accounted for dip errors by stopping the turn before the compass reached 360°.
Example Sentence 2
Dip errors caused the compass to lag during the rollout from a turn onto a northerly heading.