With a failure of the pilot's RTU, how can the VHF COMM and NAV frequencies be changed?

• A. Use the Backup Tuning Unit
• B. Use the 1/2 switch on the F/O RTU only
• C. Either use the Backup Tuning Unit, or press the RTU inhibit switch light for the pilot RTU and use the 1/2 switch on the F/O RTU to change the frequency
• D. It cannot be changed

Answer: (C)

When the pilot’s RTU fails, you still have two ways to retune the VHF COMM and NAV frequencies. One is to use the Backup Tuning Unit, which is an independent path for dialing in the desired frequencies. The other path is to inhibit the pilot RTU—indicated by the RTU inhibit light—and then use the copilot’s RTU, specifically the 1/2 switch, to change the frequency. This setup lets the crew maintain control of radio tuning even with one RTU out of service.