Emergency Service Level (ESL) is designed to provide what?

• A. Reliable, minimal function including air traffic control when primary is unavailable
• B. Full operational capability during all times
• C. Data backups only
• D. Passive monitoring only

Answer: (A)

Emergency Service Level is about keeping essential operations running when the primary system fails. It ensures reliable, minimal function so critical tasks, such as air traffic control, can continue even during an outage. This means the system provides enough capability to maintain safety and control, not full, all‑time operations.

The other options don’t fit because ESL isn’t about always-on full operations, nor only about data backups, nor merely passive monitoring. It’s about sustaining the critical function at a usable, reduced level when the main system is unavailable.