If all aircraft electrical power is lost, how long can the onboard batteries provide backup power?

If all aircraft electrical power is lost, how long can the onboard batteries provide backup power?

• A. 10 minutes
• B. 30 minutes
• C. 60 minutes
• D. 15 minutes

Answer: (B)

When all electrical power is lost, the batteries are there to keep the essentials alive for a finite window long enough to manage the emergency and land safely. The backup power duration is designed to be about 30 minutes, which provides enough time to keep critical flight instruments, communications, navigation, and emergency lighting operational while the crew follows procedures and establishes a safe landing or switches to an alternate power source. Ten or fifteen minutes would often be too short for a complete approach and landing, while sixty minutes would require a much larger, heavier battery with little justification for typical operations.

When all electrical power is lost, the batteries are there to keep the essentials alive for a finite window long enough to manage the emergency and land safely. The backup power duration is designed to be about 30 minutes, which provides enough time to keep critical flight instruments, communications, navigation, and emergency lighting operational while the crew follows procedures and establishes a safe landing or switches to an alternate power source. Ten or fifteen minutes would often be too short for a complete approach and landing, while sixty minutes would require a much larger, heavier battery with little justification for typical operations.