Title: A Comprehensive Guide to Missed Approach Procedures for CAT II and CAT III Approaches
Introduction
In the complex world of aviation, pilots encounter a myriad of scenarios that demand precise procedures and swift decision-making. One critical aspect of instrument approaches is the missed approach procedure, a protocol designed to ensure the safety of the flight when the conditions or circumstances deviate from the planned descent. This article will delve into the specifics of missed approach procedures for Category II (CAT II) and Category III (CAT III) approaches.
Understanding the Terminology
Before we delve into the details, it's crucial to understand some key terms:
1. HAT - Height Above Touchdown: The height of the aircraft above the designated point of touchdown on the runway.
2. DH - Decision Height: The specified altitude at which a decision must be made during an approach to either continue the descent or execute a missed approach.
3. AH - Alert Height: In CAT III approaches, the altitude above the runway at which the aircraft's autopilot must be disengaged to ensure a smooth transition to manual control.
4. AGL - Above Ground Level: The height of an aircraft above the terrain or runway.
Missed Approach (CAT II)
For CAT II approaches, the missed approach procedure is initiated when the aircraft is at or below 1,000 feet HAT and above the Decision Height (DH). However, if crew incapacitation is evident, it is recommended to continue the approach if below 100 feet AGL. This exception acknowledges the critical phase of the approach and the potential challenges associated with a sudden crew incapacitation.
Missed Approach (CAT III)
CAT III approaches involve even lower visibility conditions, requiring a higher level of automation. The missed approach procedure for CAT III approaches is activated at or below 1,000 feet HAT and above either the Alert Height (AH) or the Decision Height (DH). However, in the case of an engine failure, the procedure can be delayed until 1,000 feet HAT, provided engine failure procedures are completed by that point. Similar to CAT II, if the aircraft is below 100 feet AGL, it is recommended to continue the approach.
Engine Failure Considerations
An interesting aspect of missed approach procedures is the consideration given to engine failures. In both CAT II and CAT III approaches, if an engine failure occurs, the crew is expected to complete the engine failure procedures by 1,000 feet HAT. Failing to do so may warrant the initiation of the missed approach procedure. Nevertheless, if the aircraft is below 100 feet AGL, it is advised to continue the approach, highlighting the importance of situational awareness during critical phases of flight.
Conclusion
In the dynamic world of aviation, missed approach procedures play a pivotal role in ensuring the safety and success of instrument approaches, particularly in adverse weather conditions. Pilots must be well-versed in the specific criteria for CAT II and CAT III approaches, including the considerations for crew incapacitation and engine failure scenarios. Adhering to these procedures contributes to the overall safety and efficiency of aviation operations.