Approach Procedures — Page 179, Lesson 256

Let’s pick this up right where the final approach segment begins. I want to walk you through the three ways a final approach can be set up, because the rules change depending on whether you’re flying a non-precision approach with a FAF, a non-precision approach without a FAF, or a precision approach. First, the non-precision approach with a FAF. FAF stands for Final Approach Fix. For this procedure, the final segment starts at the FAF and ends at the MAPt — that’s the Missed Approach Point. The FAF is positioned on the final approach track, and its distance from the threshold of the landing runway is chosen so that you have enough room to configure the aircraft for final approach and landing, and to descend from the intermediate altitude down to the MDA/H — that’s the Minimum Descent Altitude or Minimum Descent Height. The MOC — Minimum Obstacle Clearance — is built into the calculation of that MDA/H, so the published value already accounts for obstacle protection. Now the numbers you need to remember. The optimum distance of the FAF from the threshold is 5 nautical miles, and the maximum is 10 nautical miles. The required descent gradient should be 300 feet per nautical mile, which is approximately 3 degrees. And here’s a key detail: a step-down fix may be incorporated for obstacle clearance purposes. If there is a step-down fix, then two OCA/H values will be published — that’s Obstacle Clearance Altitude or Obstacle Clearance Height. One value applies before the step-down fix, and one after, because the obstacle clearance changes at that point. Now the second case: non-precision approach without a FAF. This situation normally occurs at an aerodrome where there is only one facility on or near the aerodrome, and that single facility is used as both the IAF — the Initial Approach Fix — and the MAPt. Because there’s only one facility, it’s unlikely that the final approach track will be aligned with the runway centre line. So in this case, you make your descent to MDA/H only when the aircraft is established inbound on the final approach track. That’s the critical difference — you don’t start descending on a timed or fix-based point; you wait until you’re properly established on the track. Now the third case: the precision approach. For ILS or MLS — that’s Instrument Landing System or Microwave Landing System — the final segment begins at the FAP, the Final Approach Point. The FAP is defined as the point in space on the localizer centre line, or on the specified MLS azimuth, where the intermediate approach altitude intercepts the nominal glide path. So it’s the point where your level intermediate segment meets the descending glide path. The FAP can occur at heights between 300 metres, which is 1000 feet, and 900 metres, which is 3000 feet. On a 3-degree glide path — that’s 300 feet per nautical mile — that height range puts the FAP between 3 nautical miles and 10 nautical miles from touchdown. And just like the non-precision case, the MOC — Minimum Obstacle Clearance — is included in the calculation for DA/H, which is the Decision Altitude or Decision Height. But here’s the precision-approach twist: it requires the pilot to fly the aircraft with no more than half-scale deflection on the glide path indicator. That’s the precision requirement — you must stay within half-scale on the localizer and glide slope to remain protected by the published obstacle clearance. So to tie it together: the non-precision with FAF gives you a defined fix to start your descent, with a step-down option and two OCA/H values. The non-precision without FAF relies on a single facility and requires you to be established inbound before descending. And the precision approach uses the FAP where your altitude intercepts the glide path, with a half-scale flying requirement to keep the MOC valid.