Definition
The lowest altitude at which an aircraft must cross a specified fix when proceeding in the direction of a higher minimum en route altitude (MEA). MCAs are charted at fixes where the MEA increases along the route of flight, ensuring the aircraft is already at the higher altitude before entering the segment that requires it.
Plain English
If the required altitude on your route goes up after a certain point on the chart, the MCA tells you the lowest altitude you must already be at when you reach that point. You climb before the fix, not after.
Context Anchor
Seen on IFR en route charts and in discussions of charted instrument altitudes.
Derivation
Minimum means the lowest acceptable value. Crossing refers to passing over a specific fix on the route. Together: the lowest altitude allowed when crossing that fix.
Why Pilots Care
Meeting the MCA keeps the aircraft safely above terrain and within reliable navigation signal coverage.
Grounding Statement
An MCA is a “be this high before you pass here” altitude.
Intuition Check
Minimum does not mean suggested or comfortable here. It means the lowest allowed altitude for crossing that point in that direction.
Example Sentence 1
The chart showed an MCA of 8,000 feet at PINEY intersection, so we began our climb early to be level at 8,000 before crossing the fix.
Example Sentence 2
The approach plate showed an MCA of 4500 feet at the intersection to maintain signal reception.