Definition of Final Approach Fix (FAF)
The Final Approach Fix (FAF) serves as a precisely defined waypoint in instrument flight procedures, marking the critical transition where aircraft commence their final descent toward the airport.
Whether identified by a navigational aid or measured as a specific distance from the runway, the FAF acts as the pivotal reference point. Here, pilots transition from the intermediate to the final approach segment, initiating their controlled descent.
Purpose of the Final Approach Fix
The Final Approach Fix serves several critical functions, primarily establishing a definitive reference point for pilots transitioning from intermediate to final approach segments. This is essential for maintaining safe, orderly approaches—particularly when instrument meteorological conditions severely limit visual references.
Upon crossing the FAF, pilots execute a coordinated sequence of critical actions:
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Configure the aircraft: Adjust flaps and landing gear.
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Manage speed: Decelerate to the appropriate approach speed.
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Begin descent: Initiate the final descent towards the Minimum Descent Altitude (MDA) or follow the glide slope.
This systematic approach ensures adequate time and distance for establishing a stabilized descent profile well before runway threshold.
By establishing a clearly defined starting point for final descent, the FAF improves situational awareness while reducing pilot workload. This standardization serves as a key safety mechanism, ensuring controlled and consistent approaches—especially during high-stress scenarios or challenging weather conditions.
Characteristics of the Final Approach Fix
The FAF has several distinctive characteristics. Positioned strategically, it gives pilots with sufficient time and distance to configure their aircraft, adjust approach speeds, and establish a stable descent profile before landing.
The FAF is always located on the final approach track—that crucial straight-line path leading directly to the runway. This positioning allows aircraft to maintain an undeviating course toward the landing threshold. While its distance from the runway varies by approach type, this positioning is always meticulously calculated to ensure an optimal descent angle.
When crossing the FAF, pilots must maintain at or above the published procedure altitude to ensure obstacle clearance. From this critical juncture, they either follow a specified descent gradient for non-precision approaches or track a precision glide slope.
While the FAF’s physical marker varies by approach type, its fundamental function remains constant. It may be defined by various navigational aids, including:
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A VOR (VHF Omnidirectional Range)
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An NDB (Non-Directional Beacon)
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A DME (Distance Measuring Equipment) fix
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A GPS waypoint
Final Approach Point vs Final Approach Fix
Though the terms Final Approach Fix (FAF) and Final Approach Point (FAP) are closely related, they apply to distinctly different approach types and should not be used interchangeably. The key distinctions are outlined below:
FAF Symbols on Approach Charts
Instrument approach charts employ specific symbols to mark the Final Approach Fix, ensuring rapid identification:
These standardized symbols are essential for rapid chart interpretation, enabling pilots to instantly pinpoint the final approach segment’s starting point on both plan (overhead) and profile (side) chart views.
In exceptional cases where a dedicated FAF is impractical, the same navigational facility may simultaneously serve as both the Initial Approach Fix (IAF) and the Missed Approach Point (Map). Such arrangements are prominently noted on approach charts.
Descent Profile During Final Approach
The descent profile commences at the FAF. Modern procedures increasingly favor a Continuous Descent Final Approach (CDA), particularly for non-precision approaches. This technique employs a constant descent rate from the FAF to approximately 50 feet above the runway—where the landing flare begins—while avoiding any level-off segments.
For descent planning, pilots calculate the required rate based on ground speed. A widely-used rule of thumb for a 3-degree approach path involves multiplying ground speed in knots by 5 to determine the target descent rate in feet per minute. For instance, a 120-knot ground speed demands approximately 600 ft/min descent.
This stabilized approach concept is fundamental to aviation safety, as unstabilized approaches rank among the leading contributors to landing accidents. Using the FAF as a precisely defined starting point is critical for establishing and maintaining this stable descent profile.
