When to Descend on a Precision Approach | How to Fly an ILS Approach
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- Опубліковано 18 гру 2023
- Do you descend to step down altitudes as soon as you can, or do you intercept the glideslope as early as possible? Only one method is truly correct, but they both have their advantages.
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Request: Do something on cross-control stalls turning base to final. That always freaks me out.
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I am amazed at how great these videos continue to be. Makes learning soooo much easier with these informative and practical lessons.
3:29 Good example and explanation. At my Part 121 airline, our procedure was we could intercept the GS prior to the FAF as long as we were inside the last step-down fix, in this case "HANAH". That way we were protected from busting an altitude for the reasons you state. We would use VNAV until inside the last fix prior to the FAF (or GS Incpt point), then arm/capture the GS.
This does not conflict with the AIM (in this example) as the GS Intercept Altitude at the FAF is "At or Above" 2000'.
I love how you always post stuff that I literally just spoke with someone about. I had an SR22 checkout who told me his DPE made him hold the higher altitude till intercepting. Another problem he faced, was he was too fast flying the approach. By the time he intercepted glide slope he was having a harder time staying ahead of the plane. I told him both ways work, but the point is to get out of the clouds & give yourself time to set up. Descending sooner he would have had more time to realize he was too fast.
Also aviation is such a joy because even the gov't realizes ADM is a situational thing still.
The issue with descending to the FAF final altitude for GS intercept is particular acute for those flying faster airplanes. Sometimes it's difficult to 'make' that altitude especially if the fixes are close together and you stay clean until GS intercept, where you put gear and flaps down.
Great point. Another good argument to intercept early in some cases.
Once again, great content for me as a newly-minted IFR pilot. This channel keeps necessary information fresh for me as a GA guy. Thanks much for the steady feed.
Voice of reason. Love it. Almost half way done with the commercial content. Thank you Dan.
I just came out of a type rating at a major US based training facility and the way that was shown as correct here is the way that I chose to fly my approaches in the sim. All of the instructors there disagreed with that method and one tried to have me intercept the glideslope at 4000 feet on an an ILS. Mind you, this was on the checkride. Needless to say, I didn't make it. Started the published missed and he paused the sim. I turned around and was like "was that intentional?" His answer was no and that I should have continued following the glideslope, which never really came in because of the altitude. I passed the checkride, but that definitely stuck in the back of my head and I've been curious about it for about a month. Though I'm a CFII, I am a bit rusty but I thought I remembered something about descending down to that charted altitude when on the inbound. Time to get back into the regs and AIM...
I use Jeppesen aporoach plates for this very reason. They depict the crossing altitudes on the profile view as it should be flown.
The published approach chart IS deceptive. I like your modified version as it more accurately depicts a proper descent profile. Following a GPS advisory glideslope below the MDA can also end badly. The minimum altitudes always rule. Good work, thank you.
Great presentation. Thanks
Super short, simple straightforward video - beautiful! Answer to your question. I step down to minimum crossing altitude at all BUT the last intersection before the lightning bolt symbol. I then maintain the last altitude to intercept glideslope just like your first example.
Love your vids! Very clear and precise! You should do a PA-44 Playlist
Great discussion of the pros and cons. In almost all situations I prefer to intercept GS earlier/higher. Useless to a pilot: Altitude above you and runway behind you.
Fantastic videos as I study for CFII, thank you for this excellent production. 😁
My director of ops at my cargo operator suggests to stay higher since the extra altitude would be handy in the event of engine failure and you would eventually intercept glideslope
the preferred way allows you more time to establish your wind-corrected heading and make lateral corrections FAC before you configure for vertical for descent.
Intercepting the GS at the proper altitude also helps prevent intercepting a false GS
Exactly!! I couldn't help but keep thinking about intercepting a false glide slope!
This is what I was going to say. if you come from above, there is a slight chance you might capture the false GS
If you are descending onto a glideslope, hasn't something else already gone pretty wrong? I don't believe ATC can put you at an altitude above the GS.
My Garmin AP makes me get down to that GS/GP altitude or else it won't capture the vertical nav. It's actually made me a better pilot because I used to just kind of wing it. Now I'm thinking ahead and planning to get down fast/early enough to hit that intercept altitude.
I have always stepped down to the GS intercept altitude to avoid any issues like the ones stated, but when I went through my CRJ type training at CAE they told me to just stay at the initial altitude until GS intercept. Never got used to it and still hate flying it that way lol.
AIM page 5-4-8, notes 3 and 4…particularly applicable for say,KORD…you will get chewed out if you fail to maintain the last assigned altitude until glide slope intercept. Multiple parallel approaches with differing platforms.
Just curious - how does *5-4-8 Special Instrument Approach Procedures* , which “authorizes only certain individual pilots and/or pilots in individual organizations to use special IAPs, and may require additional crew training and/or aircraft equipment or performance, and may also require the use of landing aids, communications, or weather services not available for public use.” apply to this video (or even to assigned approach altitudes for intercept into Chicago)?
It doesn’t really…I was referencing page 5-4-8 rather than paragraph 5-4-8
@@goose8494 - Thanks. What paragraph are you referencing?
My AIM copy is dated 4/20/23….Chapter 5, Section 4, paragraph 5-4-5, Notes 3 and 4 ( on page 5-4-8) ..(fairly unique circumstances, I appreciate but I operate into these regularly)
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Drive and dive!
I believe staying higher for longer may have a false GS signal. The odds are not high but I think it's possible.
You're correct. Another good reason to stay at GS intercept, at least when your last assigned altitude is well above it.
This is what I was taught. But I do both methods.
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As someone early in IFR training, I am hoping to clarify the instruction "maintain 3000 until established". In this case, does that just mean maintain 3000 until you are established on the localizer and then you can descent to any of the minimum altitudes on the approach plate prior to intercepting the glideslope at published altitude or would this instruction of "maintain 3000" require you to stay at 3000 until you are established on localizer AND glideslope? If the former, would you ever get instructions like "maintain 3000 until glideslope intercept" where the controller really does want you to ignore published minimum altitudes and maintain altitude until you have glideslope guidance?
Great question. In most cases this means maintain 3,000 until intercepting or established on localizer. For an ILS, the actual phraseology will be more like "until established on localizer." There are very rare examples, such as on simultaneous parallel approaches, where the approach plate itself will mandate you maintain last assigned altitude all the way through glideslope intercept. This is typically done for wake turbulence separation.
I just flew an approach (different one, but same issues) in the simulator, and I DID mistake the entire profile as a constant glide slope. (I have no idea what I’m doing.) Ending up WAAAAAAY too low at the final approach fix, I read the distance between each point and figured the first leg should be about -200/250 feet per second. (Twice the distance, half the rate of descent.)
And that left bar displacement in both examples?
Woah. Trim that rudder.
I'm actually surprised this is an issue for people.
Agree.I thought it is crystal clear how to fly the ILS/LOC approach. If you fly the precision ILS approach, maintain 3000, then follow glide slope; for non-precision VOR approach, do step-down.