What should the altimeters be within during an instrument cockpit check?

The correct answer is that the altimeters should be within ±75 feet of a known elevation during an instrument cockpit check. This tolerance ensures that the altimeters are accurately calibrated and functioning properly, which is critical for the safety of flight operations. Maintaining a close margin within this range allows pilots to rely on their altitude readings during instrument flight conditions and prevents any significant discrepancies that could lead to altitude misjudgments.

In aviation, particularly in instrument flight rules (IFR), precise altitude readings are crucial for following air traffic control instructions, avoiding collisions, and ensuring safe navigation. The ±75 feet standard is a balance between operational requirements and realistic calibration capabilities of altimeters, allowing for minor variations while still ensuring safety in the cockpit.