Autopilot question

[Cyril Gibb]

I've got a Century 2000 autopilot with a NSD360 HSI driven off a GNS430 (non-WAAS... sigh).

The autopilot consistently flies a course parallel to and slightly to the left of the GPS magenta course line.

The HSI matches the GPS indication.... about a dot left of the course, so the GPS and HSI agree.

 

I know that on the front panel of the Century 2000, the 2nd adjustment from the left is to adjust the heading bug (which is bang on).

 

Do any of the other front panel adjusters set the course offset ??? or is that some internal tweak?

 

[Marauder]

I've got a Century 2000 autopilot with a NSD360 HSI driven off a GNS430 (non-WAAS... sigh).

The autopilot consistently flies a course parallel to and slightly to the left of the GPS magenta course line.

The HSI matches the GPS indication.... about a dot left of the course, so the GPS and HSI agree.

I know that on the front panel of the Century 2000, the 2nd adjustment from the left is to adjust the heading bug (which is bang on).

Do any of the other front panel adjusters set the course offset ??? or is that some internal tweak?

Does the 430 series have the parallel track offset like the GTN series? If it does, could this be the issue?

[Cyril Gibb]

I can't find that capability in the GNS430 manual.... WAAS only I think....

Neat feature however......

[midlifeflyer]

I can't find that capability in the GNS430 manual.... WAAS only I think....

Neat feature however......

 

I think that's right - a WAAS feature (it's in the 430W/530W). But considering the steps to turn it on (next to last choices on the menu when in the flight plan page) not too likely you would have done it accidentally.

[Cyril Gibb]

I think that's right - a WAAS feature (it's in the 430W/530W). But considering the steps to turn it on (next to last choices on the menu when in the flight plan page) not too likely you would have done it accidentally.

In addition to that, the HSI shows left of track.  I just read the WAAS parallel info and I think that the HSI would show "on track" when the parallel setting was being used.

[dooleypster]

I've got a Century 2000 autopilot with a NSD360 HSI driven off a GNS430 (non-WAAS... sigh).

The autopilot consistently flies a course parallel to and slightly to the left of the GPS magenta course line.

The HSI matches the GPS indication.... about a dot left of the course, so the GPS and HSI agree.

 

I know that on the front panel of the Century 2000, the 2nd adjustment from the left is to adjust the heading bug (which is bang on).

 

Do any of the other front panel adjusters set the course offset ??? or is that some internal tweak?

I have a similar experience where my indications are always 1/2 dot right of course.  The avionics shop tells me it's an internal tweaking they can do if it persists.

[Piloto]

The offset could be due to dirty contacts on the A/P connector. Try contact cleaner.

 

José

[Awful_Charlie]

My old Arrow with a Century & NSD/430 used to do that. I just accepted it, as it reduces the chance of hitting someone on the reciprocal track!

[carusoam]

Awful Chuck,

I thought the same thing. But the choices are a pretty wide swath 1 - 99 miles?

With a WAAS gps...

A few hundred feet would be nice.

More than a mile puts you close to the edge of the protected Victor airway. 4nm wide.

What are people using the offsets from 2 - 99 for?

Best regards,

-a-

[Hank]

I flew visually offset a half dozen or so miles going back to WV from the Niagara PPP, because I wanted to avoid one cloud with a heavy rains shaft coming out the bottom. Turned out to be the end of a line > 50 nm long, I was just lined up perfectly so it looked like a single cloud. I dodged right at the southern edge of Lake Erie, and stayed to the right across frequency changes until well past Erie, PA. There were some impressive showers coming out of that line of storms, too. An offset function would have worked, but because it was clear behind them I just jinked over and maintained visual separation.

P.S.-- the only Airway I've ever been assigned was from Daytona to Melbourne, in both directions, but the airliner I rode went the same route too, but much higher.

[Marauder]

I have heard several explanations for the parallel track feature. One was that it was added to assist in SARS to duplicate a flight path of a plane but parallel to allow you to look down and see the flight path.

Another was for what Hank described. And a third was to allow VFR flights to follow Victor airways but offset enough not to interfere with traffic on the airway if they decided to climb or descend.

Be nice if heard the real answer. I have used it once to see what it does.

[bonal]

I have heard several explanations for the parallel track feature. One was that it was added to assist in SARS to duplicate a flight path of a plane but parallel to allow you to look down and see the flight path.

Another was for what Hank described. And a third was to allow VFR flights to follow Victor airways but offset enough not to interfere with traffic on the airway if they decided to climb or descend.

Be nice if heard the real answer. I have used it once to see what it does.

This post made me think and here is a ignorant VFR pilot question. on some long XC trips I have planned and flown the Victors using VOR waypoints I am controlled by ATC following am I an interference by doing this?

[Ned Gravel]

Bonal:

 

If you are doing as you have suggested, you may not necessarily be in contact with ATC, but you are being predictable, and that (we are often told) is one of the things they want from us.  You are doing exactly what I would be doing if I ended up squawking 7600 and executing the "loss of comms" evolution during an IFR flight.  One of the success factors of that process is predictability.  I am doing what they think I should be doing, so it is easier for them to manage the airspace without blowing everyone off because some hotdog is making it up as he goes along.

 

If, indeed, you are in constant communication with ATC throughout (flight following), then it will have the same result.  ATC likes us to follow the roads (IFR = I Follow Roads).  It makes things more predictable on their displays.

[bonal]

Thanks I always get flight following when on loger trips or when I am going to busy areas. Oakland center is very accommodating and on a few occasions I have been directed for traffic avoidance. I like to fly the VOR's cause it makes for easy positioning updates and if something were to go bad ATC would know right where I am making it easier to provide help. I just wanted to make sure I was not getting in anyone's way. It also is fun cause the controlles are talking and I'm listening getting my handoffs and all that cool pilot stuff.

[dooleypster]

I have heard several explanations for the parallel track feature. One was that it was added to assist in SARS to duplicate a flight path of a plane but parallel to allow you to look down and see the flight path.

Another was for what Hank described. And a third was to allow VFR flights to follow Victor airways but offset enough not to interfere with traffic on the airway if they decided to climb or descend.

Be nice if heard the real answer. I have used it once to see what it does.

The primary purpose for the offset feature is "SLOP" (strategic lateral offset procedure), used on the North Atlantic tracks to aide in congestion and avoid turbulence from other aircraft.  Airliners will typically offset anywhere from 1/2 to 2 miles from track to the right.  With RVSM airspace in effect it is really quite congested up there every night.  Here in the small airplane VFR world, as others have indicated, predictability is key to the controllers, and a parallel track to almost anything within the airway path of 8 miles is preferable to random deviations in a chaotic manner.

[carusoam]

Keep in mind...

Altitude is the primary method for separating airplanes flying on the same centerline.

We can control it within feet using our 'sensitive' altimeters.

If you decide to fly VFR on a victor airway at IFR altitudes, you will probably get some follow-up FAR training...

My plane is about 10’ tall with the gear stowed...

A small variation in altimeter pressure setting using an analog knob makes the big sky theory REALLY BIG.

Using digital set-points on digital APs driven by WAAS GPS you may find that the big sky is getting smaller in a precise way.

Offsets using +/- 100' in 3D makes sense for this application. 99 mile offset seems like the designer of the GPS box found an easy function to program in.

Flying low VFR on weekends using VOR navigation you can see plenty of traffic as you get near the station.

Flight following is a great idea.

Best regards,

-a-