The maximum altitude loss permitted during an unpressurized instrument static pressure system integrity check is

The maximum altitude loss permitted during an unpressurized instrument static pressure system integrity check is

• A. 50 ft per minute
• B. 200 ft per minute
• C. 100 ft per minute
• D. 300 ft per minute

Answer: (C)

During an unpressurized instrument static pressure system integrity check, the key thing to control is how quickly the altimeter can indicate a change in altitude. Static pressure changes drive the altimeter and the vertical speed indicator, so you want to avoid rapid altitude changes that could mask a leak or fault in the static system. The limit of 100 ft per minute sets a conservative, safe rate for observing the system’s response. If the altitude changes faster than 100 ft/min during the check, it suggests an abnormal leak, blockage, or venting condition in the static system, meaning the system integrity may be compromised. Other rates would be either too permissive or not appropriate for detecting faults reliably, which is why 100 ft/min is the correct limit.

During an unpressurized instrument static pressure system integrity check, the key thing to control is how quickly the altimeter can indicate a change in altitude. Static pressure changes drive the altimeter and the vertical speed indicator, so you want to avoid rapid altitude changes that could mask a leak or fault in the static system.

The limit of 100 ft per minute sets a conservative, safe rate for observing the system’s response. If the altitude changes faster than 100 ft/min during the check, it suggests an abnormal leak, blockage, or venting condition in the static system, meaning the system integrity may be compromised.

Other rates would be either too permissive or not appropriate for detecting faults reliably, which is why 100 ft/min is the correct limit.