Up to what altitude is the maximum pilot–copilot altitude difference limited to 50 feet?

• A. 4,000 feet
• B. 5,000 feet
• C. 6,000 feet
• D. 7,000 feet

Answer: (B)

The key idea here is that the two pilots must have a highly synchronized altitude reference. Keeping the pilot’s and copilot’s altitude readings within 50 feet helps ensure both crewmembers are looking at the same altitude, which is crucial during climbs, descents, instrument approaches, and any operation near terrain or controlled airspace. The 50-foot limit is specified for operations up to 5,000 feet, where the potential impact of altimeter errors (from instrument tolerances, temperature effects, and static-port discrepancies) is most consequential for crew coordination and decision-making. Above 5,000 feet, the strict 50-foot cross-check is not applied in the same way, as the flight regime shifts toward higher-altitude operations where the risk dynamics are different and such a tight differential isn’t required by this limitation.