Definition of Instrument Approach Procedure (IAP)
An Instrument Approach Procedure (IAP) is a set of planned maneuvers that pilots follow using flight instruments. These procedures ensure safety by providing specific protection from obstacles, starting from the initial approach fix or the beginning of a defined arrival route. The goal is to guide the aircraft to a landing point. If a landing isn’t possible, the procedure leads to a holding position or ensures obstacle clearance while en-route.
IAPs are categorized into three main types:
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Non-Precision Approach (NPA)
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Approach Procedure with Vertical Guidance (APV)
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Precision Approach (PA)
Description of IAP Segments
An instrument approach can be broken down into five distinct segments:
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Arrival Segment: This segment transitions the flight from the en-route phase to the approach phase.
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Initial Approach Segment: It starts at the Initial Approach Fix (IAF) and ends at the Intermediate Fix (IF).
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Intermediate Approach Segment: Typically, this segment begins at the IF and finishes at the Final Approach Fix (FAF) or Final Approach Point (FAP). Here, pilots adjust the aircraft’s speed and configuration to prepare for landing, keeping the descent gradient shallow.
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Final Approach Segment: This part starts at the FAF/FAP and concludes at the Missed Approach Point (MAPt). Pilots align and descend for landing during this segment. Depending on the aerodrome, the final approach may lead directly to a runway or require a visual maneuver.
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Missed Approach Segment: This segment kicks off at the MAPt, providing safety from obstacles during the missed approach maneuver. It outlines where the missed approach starts and where it ends. Each IAP has a single, straightforward missed approach procedure to help manage pilot workload in high-pressure situations.
Types of Final Approaches
There are four defined types of final approaches:
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Non-Precision Approach (NPA) with FAF
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NPA without FAF: Sometimes, an aerodrome only has one facility that serves as both the IAF and MAPt, which means no separate FAF is established.
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Approach with Vertical Guidance (APV): This method offers both lateral and vertical guidance but does not meet precision approach standards.
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Precision Approach (e.g., ILS): This segment begins at the FAP, where the intermediate approach altitude meets the nominal glide path.
Notes on Approach Procedures
Not all IAPs include every segment. Instrument approach procedures are published in the Aeronautical Information Publication (AIP) under the AD section. The arrival segment appears in Standard Arrival (STAR) charts, while other segments are detailed in instrument approach charts. Although multiple STARs might be on one chart, each IAP is usually represented on its own chart sheet, though it’s possible to combine similar approaches, like all ILS approaches, onto one chart.
Visual Examples
For reference, examples of STAR charts and instrument approach charts can be found in the AIP.
