Comments on: When an ATC change isn’t really a change at all

By: satrap

satrap — Fri, 13 Nov 2009 01:40:43 +0000

great post. i just cant get my head around the idea of not taking this oppertunities to get what you want online.

By: Joel Blue

Joel Blue — Tue, 05 May 2009 01:39:29 +0000

GPT 33-56-33N/118-24-25W LAX

By: Joel Blue

Joel Blue — Tue, 05 May 2009 01:35:10 +0000

The biggest problem is the “old” center computers, each center computer only knows all the fixes in it’s own airspace, and some of the bigger fixes in all the other airspace. If you file fixes (i.e. GPT..LAX) the computer computes a fix close to the center boundaries and adds them to the flight plan information then you get a FRC, because the computer needs a fix to figure the next sector to get the flight progress strip sent to. But if you file departure airport fix direct to a Lat/Long (i.e. GPT..Lat/Long..LAX & add remarks Lat/Long is LAX) the computer somehow knows how to send the flight progress strips to the right sectors, & never adds an unnecessary fix (at least I’ve never seen an added fix, but I’ve only been a controller since 1977).

By: Paul Goforth

Paul Goforth — Sun, 03 May 2009 14:09:06 +0000

“Pilots and controllers” are much like “Labor and Management” they have been gravelling for years and somehow just tolerate each other!.

By: Jean Paul

Jean Paul — Sat, 02 May 2009 17:28:00 +0000

After reading the comments from Joe Shugart and Brian Veazy I now understand where the problem lies.

By: Joe Shugart

Joe Shugart — Sat, 02 May 2009 05:15:28 +0000

Correction on the airway dimensions: the protected airspace extends beyond 4nm when 51nm from the navaid on a 45 degree angle until, at 130nm, it reaches its maximum distance of 10nm from the centerline.

By: Joe Shugart

Joe Shugart — Sat, 02 May 2009 05:02:29 +0000

Yes, David, from an ATC separation perspective, a direct clearance from X VOR to Y intersection is not the same as one from X VOR V123 to Y intersection. The reason is that a direct clearance has no defined dimension upon which to base separation from terrain or other aircraft. In contrast, airways, as you mentioned, are defined as plus and minus four miles (up to 10 at 51nm from the navaid). It helps to remember that the clearance issued prior to departure is primarily a non-radar routing. Even when using radar separation, controllers must know the heading of the “direct” aircraft in order to assign a sufficiently divergent heading to another IFR aircraft before discontinuing vertical separation.

By: David Heileman

David Heileman — Fri, 01 May 2009 21:18:34 +0000

Brian Veazey, it helps me to know that you are a controller; I am a pilot. Since VOR equipment on aircraft is only required to be accurate +/- 6 degrees, and since a VOR can be misaligned (relative to true north) by as much as 2 degrees before the FAA will re-align it, the whole system is inherently “fuzzy”, and is designed to be safe despite the fact that it is fuzzy. The AIM (section 5-3-5) addresses the reality that airplanes do not turn instantaneously, and also talks about the 4nm of “latitude” on each side of an airway/route centerline. I still don’t understand how, when one is talking only about VOR navigation, a clearance of “X direct Y” (where Y is an intersection on the 123 radial of X) is any different than a clearance to go “X X123R Y”. If these clearances really have different meanings, I would love to understand exactly how they are different, because I was taught to treat them exactly the same.

To Joe Shugart’s comment, are you really saying that a direct clearance from X VOR to Y intersection (where Y is defined by a radial of X) does not provide traffic separation or terrain clearance!?!? I hope you are incorrect! It certainly contradicts my understanding…

I gave up filing a specific route shortly after getting my instrument rating because it seemed that my filed route was always ignored by the system anyway. For the two routes I fly most frequently, the system always gives me the same clearance no matter what I file, and I don’t think I’ve actually flown the entire clearance even once — I always get amended clearances in the air — although usually the amendments are vectors, or allow me to shortcut (i.e., direct to MXE VOR when the original clearance was EMI V419 MXE).

I do have a couple of pet peeves with ATC clearances (please don’t take this personally).

#1 peeve is getting clearance direct to an intersection when I am not RNAV-capable and I am not on one of the radials defining the intersection. This happens to me all the time. Hello! Isn’t this why I specified slant alpha when I filed the flight plan?

#2 peeve is getting clearance to an intersection or waypoint that is not depicted on the low altitude chart. This has only happened to me once. I had already accepted the clearance before discovering that I had no way to fly it. Fortunately my radios did not pick that moment to fail, so I was able to request an amended clearance. But shouldn’t a pilot be able to assume that any fix given in a clearance will be charted?

By: Elliott Schiffman

Elliott Schiffman — Fri, 01 May 2009 19:08:35 +0000

Stop making excuses about .01% when it is computer programming. I often file through the NY airspace over JFK where V1, V16 and V229 overlap. It is common, regardless of how I file, to get “Standby for route change, advise when ready to copy” and the change will be simply changing one of the above for another when all three are collocated.

By: Brian Veazey

Brian Veazey — Fri, 01 May 2009 18:53:24 +0000

David Heileman–

I’ve been a big-city controller for 27 years now and have had more than one unpleasant experience with this issue. A airplane two miles south of where he’s expected to be can be a problem.

A couple of points:

1. I should have said it’s been better with FMS, not necessarily GPS.
2. Where in the heck did you get the four miles of latitude you cite above? You’re
expected to be on the route centerline.
3. You sort of answered the question for yourself: “…no decent pilot would ever home to a fix.” Whoever wrote the original ASRS complaint above sure as heck isn’t a decent pilot. He gets a clearance and then complains about having to get a chart out to check it. Give me a break. A decent pilot checks the SID, route, and STAR against the FMS (or whatever)every trip. That FAR is 91.103.
4. Mr. Darby above is quite correct. NAS computers do spit out loads of superfluous PDRs, etc., and ATC is remiss to issue them in clearances.