Autoland Systems

What is an Autoland System?

An autoland system is an integrated set of aircraft avionics and flight control components that allow the aircraft to perform a fully automated landing. This includes the approach, flare, touchdown, and rollout, often without pilot input beyond monitoring. Autoland is critical for operations in low visibility, such as CAT II and CAT III approaches, where manual landing would be unsafe or impossible.

Types of Autoland Systems

• Fail-Passive: If a failure occurs, the system disengages without causing significant deviation; the pilot must take over to land.
• Fail-Operational: Even if a failure occurs below alert height, the system can complete the landing automatically. If a further failure happens, it reverts to fail-passive.
• Fail-Operational Hybrid: Combines a fail-passive autoland with a secondary independent system, allowing manual completion of landing using alternate guidance (e.g., head-up display).

Autoland Requirements and Procedures

• Aircraft must be certified and equipped with dual ILS receivers, autopilots, and radio altimeters for CAT II/III approaches.
• The aerodrome must be approved for low visibility operations, and low visibility procedures (LVPs) must be in effect.
• Crew must verify all equipment is serviceable, and both the crew and airport meet all requirements before commencing autoland.
• Operators must provide specific procedures in their manuals, including equipment checks, crew responsibilities, and actions for system failures.

Autoland Minima and Limitations

• Autoland minima depend on both aircraft and airport certification. For CAT III, decision heights can be as low as 0–50 ft, with runway visual ranges (RVR) down to 75 m.
• Any degradation of ground or airborne systems may require higher minima or prohibit autoland.

Practical Considerations

• Autoland is often used in fog or other low visibility conditions to maintain schedule reliability and safety.
• Crew training and simulator checks are mandatory for autoland operations.

Key Terms

• Autoland CAT III: Refers to the most demanding category of automatic landings, with the lowest visibility minima.
• Autoland Procedure: The step-by-step process for setting up, monitoring, and executing an autoland approach and landing.