DAL A
Catastrophic Failure Conditions
- Flight Control Computers (e.g., Fly-By-Wire Systems)
- Full Authority Digital Engine Control (FADEC)
- Primary Avionics Processing Systems (e.g., Flight Management System, FMS)
- Autopilot Systems
DAL B
Hazardous/Severe-Major Failure Conditions
- Secondary Flight Controls (e.g., Flaps / Slats Control)
- Engine Indication and Crew Alerting System (EICAS) / Electronic Centralized Aircraft Monitoring (ECAM)
- Traffic Collision Avoidance System (TCAS)
- Ground Proximity Warning System (GPWS/TAWS)
DAL C
Major Failure Conditions
- Weather Radar System
- Terrain Awareness and Warning System (TAWS)
- Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR)
- Secondary Navigation Systems (e.g., VOR, DME, ADF)
DAL D
Minor Failure Conditions
- Cabin Pressure Monitoring System
- Non-Critical Crew Displays (e.g., In-Flight Entertainment Systems, Passenger Announcement System)
- Some Maintenance and Diagnostic Software
DAL E
No Safety Effect
- Cabin Entertainment Systems
- Passenger Wi-Fi and Internet Connectivity
- Electronic Flight Bags (EFBs)