In case of navigation failure, which instruction should be followed until further notice?

In case of navigation failure, which instruction should be followed until further notice?

• A. Last ATC clearance
• B. Filed flight plan
• C. Current weather briefing
• D. Assigned altitude

Answer: (A)

When navigation equipment is not available, the safe and orderly thing to do is to follow the last ATC clearance you were given until you hear otherwise. That clearance is the authoritative instruction you rely on to stay on a known route and altitude, which helps ensure separation from other traffic and avoids improvising a course you might not be able to verify without navigation aids. The filed flight plan is only a guide for planning and initial routing and may no longer reflect ATC’s current instructions once you’re airborne. A weather briefing, while important for planning, doesn’t dictate what you should do when navigation is down. Relying only on the assigned altitude ignores the complete directive of the last clearance, which includes both route and altitude together.

When navigation equipment is not available, the safe and orderly thing to do is to follow the last ATC clearance you were given until you hear otherwise. That clearance is the authoritative instruction you rely on to stay on a known route and altitude, which helps ensure separation from other traffic and avoids improvising a course you might not be able to verify without navigation aids.

The filed flight plan is only a guide for planning and initial routing and may no longer reflect ATC’s current instructions once you’re airborne. A weather briefing, while important for planning, doesn’t dictate what you should do when navigation is down. Relying only on the assigned altitude ignores the complete directive of the last clearance, which includes both route and altitude together.