What is the flashing interval of the DME white light indicator during a pre-flight check?

The flashing interval of the DME (Distance Measuring Equipment) white light indicator during a pre-flight check is set to every 10 seconds. This interval is vital for ensuring that flight attendants and crew members can confirm the operational status of the DME before takeoff. The consistent timing helps in establishing a reliable routine during pre-flight checks, allowing for quick visual verification that the system is functioning as expected. This is particularly important for maintaining safety standards and ensuring readiness for flight operations. The choice that states a 10-second interval aligns with standard procedures, ensuring crew preparedness throughout the pre-flight process.