IAP Procedure.
 

Hi All, Happy Holidays

I have a question. What is the proper procedure when intercepting the ILS at 3000ft out side the IAF with a step down to 2100ft depicted from the IAF till FAF, do you just stay all the way at 3000 till glide slope intercept or is the proper procedure to descend to 2100 after IAF till glide slope intercept? At which ALT will allow you to identify a false glide slope? My Captain says we will stay at 3000 till glide slope intercept no sense in destabilizing the approach by descending to 2100 plus you have more ALT to work with if something goes wrong.

You’re thought and comments.

Happy Flying

Seems to me that if your descent is at least 500 ft p/m then you're fine staying on glideslope 3000ft all the way in, especially if your configured and stabilized.

I would also wait for the glide slope. Why descend and level one more time for no reason?

From a procedure design viewpoint, the minimum altitude at the FAP is just that - a minimum. About the only reason I can think of to justify the descent might be to avoid a false GP. However, if you start down from 3,000 feet at GP intercept and pass the FAP at or about 2100 feet, it'd be a fair bet that you're on the correct GP.

There may be some local condition or other that makes it advisable to descend to 2100 feet after passing the FAP but there would probably be some sort of explanation about that on the chart, or in related documents for the airport. One of these might be related to short range on the GP, but this would surely be notified in an official publication.

However, all things considered, I see no operational reason not to intercept the GP at 3,000 feet - if you can independently confirm that you're at the right distance from the landing THR.

As someone who has posted quite a bit about false GPs, I'd like to add my agreement to all the other replies here. I can't see anything wrong with intercepting at 3000ft outside the IAF, which would imply that you're at a good distance out and intercepting from below.

Opinions vary on where the first false GP is found. I expect it will vary with equipment and location, but as far as I can make out the lowest you could expect is at about 6 or 6.5 degrees. Roughly 6000ft at 10nm, compared with your standard 3 degree/ 3000ft at 10nm.