Procedure turn inbound

[Uncle Leo]

You are doing a full approach with a PT. The inital altitude at the IAF is 4000. The FAF crossing altitude 3000. When can you descend to 3000?

A. When PT inbound and the needle being used to define the final approach
course comes alive.

B. When the needle being used to define the final approach is centered.

C. Something else altogether?

If you have an AIM, FAR, TERPS, or some other reference I could use that too.

 

[ERJdca]

Uncle Leo,

If i understand your question correctly, the required approach altitude is 4000ft till the intermediate phase of the approach? If thats the case, you may descend to 3000 when established on the intermediate phase of the approach. That would be within 10 degrees of the final approach course and 10 miles (normally-or whatever distance approach chart dictates) and cleared for the approach.

Been a long time since i instructed but i would say its in the Instrument Flying Handbook for sure. Hope that helps,

ERJDCA

 

[SBD]

Look on the profile view. It tells you when you can descend.

 

[Uncle Leo]

Uncle Leo,

If i understand your question correctly, the required approach altitude is 4000ft till the intermediate phase of the approach? If thats the case, you may descend to 3000 when established on the intermediate phase of the approach. That would be within 10 degrees of the final approach course and 10 miles (normally-or whatever distance approach chart dictates) and cleared for the approach.

Been a long time since i instructed but i would say its in the Instrument Flying Handbook for sure. Hope that helps,

ERJDCA

This is what I had always thought and when I last instructed 9 years ago it was what I taught.

I got into a debate with another pilot and I wanted to be sure I was not doing something stupid or dangerous. I will try to find the box that has my
Instrument Flying Handbook in it to verify.

 

[A Squared]

You are doing a full approach with a PT. The inital altitude at the IAF is 4000. The FAF crossing altitude 3000. When can you descend to 3000?

A. When PT inbound and the needle being used to define the final approach
course comes alive.

B. When the needle being used to define the final approach is centered.

C. Something else altogether?

If you have an AIM, FAR, TERPS, or some other reference I could use that too.

Let's clarify a little. I assume your speaking of an approach where the PT altitude is 4000 ft, and the first intermediate altitude is 3000 ft, right?

There are two questions, really:
1) What will keep me from hitting something hard,

and

2) what will keep me from getting a pink slip on a checkride, or an enforcement (should it come to that)

I've always considered the first question to be much more interesting, so we'll deal with that first. On a simple VOR approach with a PT, the intermediate segment protected area is splayed out away from the VOR. 10 miles from the VOR it gives 1000 ft of protection, 4 nm either side of the course, plus an additional 2 nm of diminishing protection. In the extreme example of intercepting the intermediate course 10 nm out (impossible with a PT that remains within 10 nm of the VOR, but we're looking for worst case scenario) you would get a live needle 10 degrees from the inbound course on a normal CDI (5 dots, 2 degrees per dot) at 10 miles and 10 degrees you'd be 1.7 miles off the course centerline, well within the 8 NM (4 nm either side) wide protected area. So, if you start down with a live needle, you won't hit anything, unless you've done something else wrong.


The other question is what is "correct" or legal. When may you descend to the altitude of the next segment? When you're "established" on the next segment, right? What is "established" The FAA doesn't define "established" in terms of degrees. The definition of within 10 degrees of course given by ERJdca comes from ICAO, which is not the official answer for operations within the US, so is interesting, but not particularly relevant. Instead, we have this from the Pilot Controller Glossary:

Established, To be stable or fixed on a route, route segment, altitude, heading, etc.

Now, it is quite common to begin descent upon getting a live needle, but are you established? Look at the plain english meaning of the words. Can you say that you're "stable or fixed" on a course when actually you are on a heading 45 degrees across that course?

I don't know the answer to this, and as far as I know, there is no official clarification, but I can tell you that there are some pilots who are adamant that you have to intercept the course with a centered needle before begining the descent, and there are probably examiners who feel the same way.

I'm not sure I'd want to be in the position of trying to convince an examiner that stable or fixed really means at a 45 degree angle to.

 

[timeoff]

You are doing a full approach with a PT. The inital altitude at the IAF is 4000. The FAF crossing altitude 3000. When can you descend to 3000?

A. When PT inbound and the needle being used to define the final approach
course comes alive.

B. When the needle being used to define the final approach is centered.

C. Something else altogether?

If you have an AIM, FAR, TERPS, or some other reference I could use that too.

Not necessarily centered, but the ICAO states within a half scale deflection. So when the needle comes inside of two and a half dots, and you are turning to the inbound course heading, it would be safe to say that you are "established". Not until then.

Consult the profile view.

 

[minitour]

You are doing a full approach with a PT. The inital altitude at the IAF is 4000. The FAF crossing altitude 3000. When can you descend to 3000?

A. When PT inbound and the needle being used to define the final approach
course comes alive.

B. When the needle being used to define the final approach is centered.

C. Something else altogether?

If you have an AIM, FAR, TERPS, or some other reference I could use that too.

Most of what I'm about to type is personal experience and opinion, so take it for what it's worth...I just feel like everyone else has covered the FAA and ICAO "standards" pretty well.

I was taught that on a LOC/ILS, when the needle comes alive you can descend. Makes sense, because of how close you are when that needle comes alive...

On a VOR/GPS approach, I was taught 3/4 scale deflection...again, makes sense because of how close to center you are...

On an NDB approach, I was taught 10 degrees of the bearing...again, how close you are...

Here's my take on it.

I try to teach the students to really get "established" and "stabilized".

Before all fixes, that includes appropriate configuration, because I didn't feel like I was configured well enough to land from an ILS coming down the slide at 100kts.

So my take on it is needle centered. I want to be established. So, once the needle hits the donut or appropriate bearing, I can start down...even if that means I'm still turning toward my reference heading, I can still start down if appropriate (although, I should have been leading the turn to final so as not to blow through the course centerline). It's just a matter of being established.

Again, this is all my opinion and limited experience talking...your milage may vary.

-mini

 

[CaptETWes]

You may descend as soon as you are on a "published segment of the approach." The gray area of this is, however, what defines a published segment of an approach. As the above poster suggests, the FAA might define it as an area within full-scale, three-quarter scale, or even less, deflection. My opinion is that if the needle is alive, you are within reception range of the navaid and thus on the segement. So, as soon as you pass the IAF and are established outbound toward the PT, you may begin the descent to the PT alititude. The Jepp profile gives you a hint by showing a line at a negative slope indicating a descent is suggested and/or appropriate. Also, keep in mind the performance of your aircraft and groundspeed. A fast descent to PT alititude might not be as necessary in a C152 as it would in, say, a G-V. In the end, as long as you are at the published altitude at the FAF (best for a stabilized descent), your descent rate and decision of when to descend is up to the PIC.

 

[CaptETWes]

If you have an AIM, FAR, TERPS, or some other reference I could use that too.

Check this out. It's a free download from the FAA, or you can buy the paper copy. Chapter 5 deals with approaches.

http://www.faa.gov/library/manuals/aviation/instrument_procedures_handbook/

 

[UndauntedFlyer]

If you're way out with plenty of time to get down, then "established" is CDI in the bullseye. If your're in closer and about on profile then "established" is CDI at one-half deflection as in the ICAO definition of established. If you're in too close and high then "established" is "case break" on the CDI. If you're on a flight test use the bullseye answer if possible but if you need to descend without delay to salvage the approach, then ask the examiner what he/she thinks on this and that's the answer.