Final Approach Fix (FAF) and Related Instrument Approach Segments

The Final Approach Fix (FAF) is a cornerstone of instrument approach procedures (IAPs), serving as the critical navigational point from which the final approach segment is executed under instrument flight rules (IFR). Proper understanding and identification of the FAF—along with its depiction on approach charts and operational requirements—are fundamental to safe and legal instrument flying.

Definition and Core Function

The FAF is the specific fix—often a radio navigation aid (NAVAID), intersection, or GPS waypoint—where the final approach segment begins. From this point, the aircraft must be fully configured for landing and is authorized to descend to the minimum descent altitude (MDA) or decision altitude/height (DA/DH) as published. The FAF guarantees obstacle clearance and marks the transition to the final portion of the approach, where alignment with the runway and a stable descent are essential.

For nonprecision approaches (e.g., VOR, NDB, or LOC), the FAF is depicted as a Maltese Cross (✠) on approach charts. For precision approaches (e.g., ILS, GLS), the FAF—more precisely called the Precision Final Approach Fix (PFAF)—is shown by a lightning bolt (⚡), representing the glide slope intercept point.

If a charted FAF is absent (as in some on-airport NAVAID approaches), the Final Approach Point (FAP) serves as the operational equivalent: the point where the aircraft is established inbound on the final approach course and authorized to commence descent.

Instrument Approach Procedure Segments

Instrument approaches are divided into four primary segments:

1. Initial Approach Segment:
   Begins at the Initial Approach Fix (IAF), transitioning the aircraft from en route to approach, often including course reversals or racetrack patterns.

2. Intermediate Segment:
   Starts at the Intermediate Fix (IF), positioning the aircraft for the final approach with correct altitude and alignment.

3. Final Approach Segment:
   Begins at the FAF (or FAP). Here, the aircraft descends toward the runway, maintaining obstacle clearance until the missed approach point (MAP) or runway threshold.

4. Missed Approach Segment:
   If a landing cannot be safely completed, this segment provides a protected path for climbing and re-entering the en route or terminal environment.

The FAF is the pivotal transition point from intermediate to final approach, critical for procedural compliance, safety, and obstacle clearance.

Charting and Identification of the FAF

Approach charts use standardized symbols and labeling for the FAF:

• Nonprecision Approaches:
  The FAF is marked with a Maltese Cross (✠) in the profile view. The fix may be a named intersection, NAVAID, or GPS waypoint, often annotated as “(FAF)” in the plan view.

• Precision Approaches (ILS, GLS):
  The lightning bolt (⚡) marks the glide slope intercept or PFAF in the profile view, indicating where descent on the glide path to DA is permitted.

• No Charted FAF:
  The FAP is used, typically where the aircraft is established inbound after a procedure turn or holding pattern.

Example Table: FAF Charting

Accurately identifying the FAF, using chart symbols and avionics cues, is essential for safe descent and compliance with published procedures.

Regulatory Framework and Operational Details

The FAF’s role is defined by both FAA and ICAO regulations:

• Commencement of Final Approach:
  For nonprecision approaches, the segment begins at the FAF (✠). For precision approaches, it begins at the PFAF (⚡) at the minimum glide slope intercept altitude.

• Pilot Actions at the FAF:

  • Complete landing configuration (gear, flaps).
  • Finalize checklists.
  • Confirm navigation and alignment.
  • Initiate descent to MDA (nonprecision) or along the glide path (precision).
  • Start timing if required for the MAP.

• No Charted FAF:
  The FAP serves the same function; descent is authorized only when established inbound after course reversal.

Glossary Definitions (FAA and ICAO)

• FAA:
  “The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment.”

• ICAO:
  For approaches with a designated FAF, this is the segment’s starting point; if not, the FAP is used (the intersection of intermediate altitude and glide path or established inbound for a nonprecision approach).

Practical Use Cases

Scenario 1: VOR Approach (Nonprecision)
Pilot identifies the FAF (e.g., “JONES” intersection, marked ✠), completes checks, and initiates descent to MDA.

Scenario 2: ILS Approach (Precision)
Pilot intercepts glide slope at the PFAF (⚡), descends along glide path to DA.

Scenario 3: No Charted FAF
After a procedure turn, the aircraft is established inbound (FAP) and descent begins.

Scenario 4: Automated Avionics
FMS or GPS sequences the FAF, provides cues for descent, and assists with compliance.

Final Approach Fix Characteristics

Related Terms and Distinctions

• Final Approach Course:
  The published track inbound from the FAF to runway or MAP.

• Missed Approach Point (MAP/MAPt):
  The fix where a missed approach is initiated if descent minimums or visual reference are not met.

• Minimum Descent Altitude (MDA):
  Lowest altitude on a nonprecision approach before the MAP.

• Decision Altitude/Height (DA/DH):
  Altitude/height at which a landing decision is made on a precision approach.

Final Approach Segment Design and Obstacle Clearance

The segment beginning at the FAF is designed for strict obstacle clearance using FAA TERPS and ICAO PANS-OPS standards. Nonprecision approaches require a defined minimum clearance from obstacles; precision approaches rely on the glide path for continuous protection.

Integration with Modern Avionics and ATC

Avionics (FMS, GPS) sequence the FAF as a key waypoint, providing cues for configuration and descent. ATC may vector aircraft to intercept the final approach course prior to the FAF and specify altitude restrictions, ensuring procedural and obstacle clearance.

Common Errors and Best Practices

Common Errors:

• Descending before crossing the FAF.
• Misidentifying the FAF.
• Failing landing configuration before the FAF.
• Omitting timing for the MAP.

Best Practices:

• Always brief the FAF location, altitude, and actions.
• Cross-check all navigation sources.
• Complete all checklists before the FAF.
• Use avionics cues and confirm positive course alignment.

Glossary: Related Procedure Terms

• Initial Approach Fix (IAF): Beginning of the initial segment.
• Intermediate Fix (IF): Start of the intermediate segment.
• Final Approach Segment: From FAF/FAP to MAP or runway.
• Missed Approach Point (MAP/MAPt): Where the missed approach procedure begins.
• Minimum Descent Altitude (MDA): Minimum for nonprecision approaches.
• Decision Altitude/Height (DA/DH): Decision point for precision approaches.

Summary of Key Points

• The FAF is the authorized point to begin final descent under IFR.
• Identified by standardized chart symbols, navigation sources, and avionics cues.
• Descent before the FAF is prohibited except by ATC clearance.
• FAP serves as the equivalent when no FAF is charted.
• All landing configuration and checklists must be completed before the FAF.

Practical Example: Chart Interpretation

On an ILS approach chart, the lightning bolt (⚡) indicates the PFAF at the glide slope intercept. For a VOR approach, the Maltese Cross (✠) marks the FAF, where descent to MDA begins and MAP timing may start.

Conclusion

The Final Approach Fix (FAF) is the foundation of safe, standardized instrument approach procedures. Its correct identification and use ensure compliance, obstacle clearance, and orderliness in the critical approach and landing phase. Understanding the FAF—and its depiction, regulatory framework, and operational significance—is essential for every pilot operating under IFR.

For ongoing proficiency, regularly review approach charts, focusing on FAF location, symbols, and requirements. Mastery of the FAF is fundamental to safe and confident instrument approaches in all conditions.