What is minimum crossing altitude (MCA)?

• A. The highest altitude at fixes.
• B. The lowest altitude at certain fixes to cross when proceeding toward a higher MEA.
• C. The minimum altitude to remain above obstacles along an airway.
• D. The altitude for the missed approach point.

Answer: (B)

Minimum crossing altitude is the lowest altitude you must cross at a designated fix when you’re continuing on a route toward a higher minimum en route altitude. It’s published at fixes where crossing at or above a higher terrain- or obstacle-protected level is needed to safely proceed to the next segment with a higher MEA. In practice, you must be at or above this crossing altitude exactly at the fix to ensure obstacle clearance beyond the fix as you move to the higher MEA ahead.

This differs from the altitude you must maintain for the entire airway segment (that’s the MEA, which ensures obstacle clearance along the whole leg) and from missed-approach altitudes, which serve a different purpose. For example, you might approach a fix where the next leg has a higher MEA; the chart may specify an MCA at that fix, meaning you must cross it at or above that altitude, then continue on the higher-altitude segment.