When can you descend

[ekuflyer]

Must be on a parallel or intercept heading after positive station passage.

 

[nosehair]

Midlife...


What definition YOU ( emphasis again...) are happy with means nothing to the FAA. And I guess that's my point and what makes questions like this so interesting for discussion.

Am I asking the definition of "established" ?? Well, yes Sir. I don't know how to be any more clear about that. It was the gist of the original question.

And, that question remains unanswered...

bafanguy, the question has been answered, as well as it ever will, by midlife and Asquare. You are not going to find a specific definitive point, like,say, the MAP, or FAF, etc. "Established" depends on knowing your position relative to the "maneuvering zone" within the approach construction. Knowing something about the construction of airspace and obstacle clearance as outlined in TERPs will show you how much lateral and verticle distance you may be away from "centerline" and still be in the "maneuvering zone" for turns and descents. Each approach is different, so the "commonly accepted" methods of insuring you are well within those lateral and verticle distance descriptions of the airspace allowed for the approach is to use the nav instruments we have, ie., "needle off the peg", or "3/4 scale". These are not FAA official definitions of the word "established", but are standardized tolerances for demonstration of pilot certification performance standards. If you can determine that the outbound segment allows, for example, one mile lateral distance from the radial at the vor "abeam" position, and four miles lateral distance from the outbound radial at the ten mile limit, and you have a GPS display that shows you are within this "maneuvering zone" for obstacle clearance at the PT altitude, then you may descend. You are "Established" within this maneuvering zone. If you're still flying vor needles, the commonly accepted method of insuring you are "in the zone" is to wait for some needle movement. But that is a technique - not a regulatory requirement.

 

[bafanguy]

nose,


Okee dokee...

 

[100LL... Again!]

Exactly, well put.

I salute your nosehair.

 

[Atccfi]

Established inbound

I was always told if you were outbound and turning inbound on the approach once the needle "came alive" you were established.... have I always been wrong? ATCCFI

 

[100LL... Again!]

Once the needle is alive, you are inside the area protected by the trapezoid.

Go ahead and descend.

As I matter of pratice, I wait until close to 1/2 scale just to ensure that it is not a transient movement of the needle.

 

[Tinstaafl]

I can't answer for FAA definitions however Australia & the UK, operating under ICAO's PANS-OPS, define 'established' as 5 deg for NDB approaches, half-scale deflection or equivalent for VOR & ILS approaches. This means that ILS & localiser approaches have a tighter tolerance WRT 'establised' than do VOR or NDB approaches.

Originally CDI & GS accuracy was specified as 2 1/2 dots however this relied on a presumption of 5 dots either side on the display. OK originally since that was how every display was done. Not so good once other dotted scales started to be used so it was eventually changed to the half-scale terminology. This also applied to test standards for licences & ratings.

For a while Australia's documents specified both the outbound & inbound descents could only be commenced once established - with established defined as I mentioned above. I seem to recall that the descent allowance has been changed in recent times so that it only applies on the inbound course ie descent outbound is now allowed as soon as the a positive indication of outbound is seen. There have been all sorts of changes in Oz procedures over the last 20yrs as they moved to various ICAO revisions so I may have the outbound descent conditions a bit backwards ie it might have been 'descend after positive outbound determined' and is now 'only descend outbound once within 5 deg'. I certainly remember it both ways but can't quite recall which was first. They may even have been one way, gone the other, then switched back.

Anyway, that's the ICAO 'take' on things.

 

[100LL... Again!]

Good point to bring up ICAO - I had read that somewhere and I think that it makes sense to use that for domestic ops as well. (As a matter of practice rather than a matter of reg)

 

[nosehair]

so I may have the outbound descent conditions a bit backwards ie it might have been 'descend after positive outbound determined' and is now 'only descend outbound once within 5 deg'. I certainly remember it both ways but can't quite recall which was first. They may even have been one way, gone the other, then switched back.

...uuuh, is that Kerry talkin'?

 

[Tinstaafl]

Nah....that's Australia's Civil Aviation Safety Authority for you, formerly Civil Aviation Authority, formerly Department of Transport & Communications, formerly Department of Transport, formerly Department of Aviation, formerly Department of Civil Aviation......and that embraces the 21 years I've been flying.

Any surprise all the procedural & system deckchairs have been shuffled multiple times as well?

 

[milflyboy]

Must be on a parallel or intercept heading after positive station passage.

Straight from AFMAN 11-217 Happened to notice you have military background

 

[profile]

The general principal is that the ICAO rules (published in PANS-OPS, etc) are the underlaying foundation. Member States (read "Countries" in the U.S. version of English) may publish their own rules, generally listed as exceptions. It could be construed from this that in the absence of any guidance to the contrary, we should follow the ICAO rules. That is indeed what many companies publish for their own operations.

A look a the TERPS will show you that the guidance should keep you inside the TERPs protected boundaries as well.

 

[profile]

Should add that I seem to recall an interp that said that under FAA "centerline" means just that. I would definitely NOT advocate just waiting for the needle to be alive. That might work alright in an ideal world, but factor in possible errors on the station plus your allowable instrument errors, and you're out of the protected airspace.

 

[100LL... Again!]

Possible, but not likely. The Terps criteria takes those errors into account.

 

[profile]

Better look again. TERPs doesn't account for many things, not only what I mentioned but also very limited as to the amount of wind consideration given for turns.