Which item is NOT listed as a required RVSM equipment item?

• A. Autopilot
• B. Altitude Alerting System
• C. Inertial Navigation System
• D. Air Data Computer

Answer: (C)

RVSM equipment is all about ensuring accurate altitude measurement and reliable altitude control to keep vertical separation. The items required are two independent sources of altitude data so the crew has a trustworthy altitude, an automatic altitude-keeping capability to maintain the assigned flight level, and an alerting system to warn if the aircraft drifts outside the allowed altitude band. An Autopilot provides the automatic altitude-keeping function, and an Altitude Alerting System warns if you’re off altitude. The Air Data Computer is part of the air data system that derives the altitude from air pressure. The Inertial Navigation System, while it’s great for precise position and heading, does not provide altitude data used for maintaining or monitoring RVSM altitude, so it isn’t listed as a required RVSM equipment item.