A non-precision approach, on the other hand, has a final approach fix, a minimum descent altitude and a missed approach point. Let’s review a bit and you will understand my dilemma.Īn ILS is a precision approach with a glide slope, localizer, final approach fix (which is the glide slope intercept point, at or below the minimum glide slope intercept altitude), decision altitude (height) and a missed approach point. The answer, that I sought, was not easily obtained and I’m not sure I’ve got it right yet. I said, very calmly, to instill confidence, as any good CFI would, “Since we aren’t going to land, let’s fly it like an ILS, straight in approach, down to the MDA and we’ll talk about it later”.īecause of a tight schedule for both of us, later didn’t come for several days, which gave me some time to research an answer. I had flown this approach literally hundreds of times before and for some reason, unknown to me, I had never noticed that with, what turns out to be, all published “ILS, circle to land” approaches you are not given a Decision Altitude (Height) but rather a Minimum Descent Altitude. I suddenly realized that, I didn’t know the answer to her question, I was the CFI and we were in actual IFR conditions (all simultaneously). I was stopped in my tracks and dumbfounded. She then looked down at the approach plate and after, what seemed like to her, an eternity because we were in actual IFR conditions, she asked me “How do I fly this approach? The approach plate is showing a Minimum Descent Altitude not a Decision Altitude”. My student immediately and mechanically pressed the PTT switch and blurted out “Roger, turn left to 320, maintain 2000 until established, cleared for the approach, 27 Hotel”. As we approached Stockton, the all familiar words came crackling over the radio “Cessna 9027Hotel, turn left to 320, maintain 2000 until established, cleared for the Stockton ILS runway 29R approach, circle to runway 11L”. The tops were 2500 feet, a typical central California Winter morning. The flight conditions were IMC with KSCK ATIS reporting a ceiling of 600 feet, sky obscured and one-mile visibility. He provides advanced instruction to multi-engine and instrument students at Genesis Flight College.One day a few years ago, I was on an instructional IFR flight from KSJC to KSCK with a very perceptive and talented instrument student. Ted Lee is a retired air force officer and flew the CF-104 and CF-18. Even if your flight test examiner fails the AP, you will still have the flight director to help you. All you have to do is increase power to maintain airspeed, and then you can look forward for the runway. At that point, the AP will have stabilized at a particular rate of descent, and when you select VS mode, this rate will be continued, and in less than a minute, the AP will level you off at MDA. Then all you do is intercept and capture the GP using the APR mode and at about 200 ft above MDA select VS mode. With this new technique, you must set the MDA as the selected altitude to be used for level off. In the past, there was no need to set the selected altitude to anything because you just rode the glide path and disengaged the AP at DA. The solution is to use VS mode for vertical guidance in the last 200 ft before MDA. More importantly, if you were doing the approach in bad weather, it would be extremely valuable to have the aircraft hold MDA accurately while you try to pick up the visual cues needed to land. This is where you can easily blow the approach on a flight test by not being able to hold MDA accurately. However, unlike precision approaches, where you immediately initiate the missed when not visual at DA, with a non-precision approach, you have to level off and continue to the MAP (or MAWP) at MDA. Here is a simple technique to stabilize this critical step in the approach.īoth LNAV and LP (the GPS equivalent to a localizer-only approach) have an advisory glide path that, when captured, will take you right to the ground. A common problem we see with students practicing non-precision instrument approaches is difficulty leveling off at the MDA.
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