Which phrase should be used when unable RNAV due GPS failure?

Which phrase should be used when unable RNAV due GPS failure?

• A. Unable RNAV due GPS failure
• B. RNAV unavailable due GPS
• C. RNAV not available
• D. GPS failure prevents RNAV

Answer: (A)

The important idea here is using concise radio phraseology that clearly states an inability and its cause in one straightforward line. When RNAV can’t be used because the GPS has failed, the phrasing that communicates this most directly is “Unable RNAV due GPS failure.” It puts the action you cannot perform (RNAV) first, and immediately follows with the reason (GPS failure), leaving no ambiguity for air traffic control or other pilots. The wording is compact and unambiguous, which is essential in flight communications. The other options are less effective because they either omit the reason or describe the situation in a way that’s less direct. For example, saying RNAV not available or RNAV unavailable due to GPS suggests a state of unavailability but doesn’t present the cause as clearly or succinctly. Saying GPS failure prevents RNAV shifts the emphasis to the GPS failure as a cause but isn’t as direct as stating the inability and its cause together in one clause.

The important idea here is using concise radio phraseology that clearly states an inability and its cause in one straightforward line. When RNAV can’t be used because the GPS has failed, the phrasing that communicates this most directly is “Unable RNAV due GPS failure.” It puts the action you cannot perform (RNAV) first, and immediately follows with the reason (GPS failure), leaving no ambiguity for air traffic control or other pilots. The wording is compact and unambiguous, which is essential in flight communications.

The other options are less effective because they either omit the reason or describe the situation in a way that’s less direct. For example, saying RNAV not available or RNAV unavailable due to GPS suggests a state of unavailability but doesn’t present the cause as clearly or succinctly. Saying GPS failure prevents RNAV shifts the emphasis to the GPS failure as a cause but isn’t as direct as stating the inability and its cause together in one clause.