ADF needles float

[willywonka 36]

If it's not realistic, why would PMDG just "make" this up and simulate it?

[martin-w 3,276]

Because it's an error! PMDG are, like you and me... fallible. Or it's a bug.

[badderjet 181]

If it's not realistic, why would PMDG just "make" this up and simulate it?

We would all like to know.

[FlyingAxx 2]

In fact i was quite amazed because is the first plane that i know off that simulate this.

Well, I have this behaviour with my inexpensive Flight 1 Pilatus PC 12 as well even if I tend to believe that there it happens unintentional.BTW, this information bit was quite new for me and I cannot remember seeing such behaviour while sitting quite often in flightdecks of the BAC1-11 (oops, long ago) being equipped with "steam gauges" only. Ok, those guys used VORs in most cases but of course they tuned in ADF frequencies as well. Regards,Axel

[HiFly 16]

As an after thought. I, like many of you, are wondering: why did PMDG model their ADF this way? Where could they have observed such behavior? An ADF is just a signal direction indicator. NDB's have various power (wattage) output depending on their use, but they all transmit on a FIXED frequency. An ADF works just like an analog tuner on an older model radio. NDB's use amplitude modulation just like an AM radio so the ADF simply directs the needle to point toward the source of the strongest (loudest) signal. Modern ADF's in most cases have a "park" or "no-op" position that the needle remains at (usually 9:00 or 3:00 dial position) until a sufficiently strong signal is received for the frequency selected. Before the plane is in range to receive full continuous and useable signal there can be a few false signals that are detected and depending on atmospheric conditions can be a distance away from the normal range. The needle will respond by moving toward the signal momentarily and then drifting back toward the parked position when the signal is lost. This is NOT the "windshield" effect simulated by NGX, however! And it is not caused by modulating frequencies. It is just an occasional intermittent false signal but once in range the needle will stabilize and point directly toward the transmitting station. This is line of sight so if flying low with obstructions it is possible that reception could be interupted in which case needle would drift back toward parked position. Could it be this temporary intermittent signal phenomenon that NGX has wrongly tried to simulate? A further note on range: in Eastern Europe particularly, many runways had the compass locators for approaches on both ends of a runway with the SAME frequency. In that case they used very low wattage so that the ADF would only point toward the nearest station (which would be the strongest signal) on the approach side of the runway being used. Or sometimes, instead, they would turn off the NDB's for the runway not being used.. Enroute NDB's, on the other hand, are designed to emit strong reliable long range signals and have high wattage output that can be received and accurately used for navigation up to 80-100n sometimes. And once in range the needles stay stabilized. A side note to those of you who are not RW pilots: an NDB cannot be tracked the same way as a VOR can. With a VOR you simply keep the needle "centered" on the dial using the AP and the plane will automatically add/subtract whatever wind correction necessary to maintain direct course. When tracking an NDB in a crosswind, the AP will not lock onto the signal nor will it automatically apply a wind correction. And keeping the needle centered will result in the plane following a curved path ever-turning more toward the NDB in the direction of the wind. In order to correctly track an NDB (required anytime an air-route is defined by an NDB as is often the case in Europe) the pilot must find the correct "crab" or offset heading to keep the needle pointing in a constant "frozen" direction. That heading then will cause the plane to fly a direct track to the NDB. The needle in this case will not be pointing at 12:00 but at an offset equal to the angle of the correction but in the opposite direction. When tracking "from" an NDB the angle of correction will be on on the tail of the ADF pointer and reversed (same side of the dial as the "crab"). Any pilot testing for an instrument rating must demonstrate proficiency in this skill and it takes much practice. Thankfully, the RW NDB signals are STEADY and reliable when in range or this task would be impossible!

[badderjet 181]

Any pilot testing for an instrument rating must demonstrate proficiency in this skill and it takes much practice. Thankfully, the RW NDB signals are STEADY and reliable when in range or this task would be impossible!

That sums it up pretty well... Also, we were required to read QDM/QDR off the instrument to the nearest degree (±1° accuracy) during approach training. Flying with a steady needle is actually not that hard, and corrections can be anticipated and performed with satisfactory results. Eventually the minima will be quite conservative, so after all you will usually hit the runway in one way or another. Not so with a jumping needle however. +1 for a soonish fix.

[i. cruz 0]

I submitted a ticket about this and this was Paul's answer. "This is actually an FSX issue in the way that the ADF behaves. Unfortunately not much we can do to settle it down." - Paul Gollnick, PMDG Team

[Houghton11 12]

I don't know...I'm not one to stir the pot but.... That's.....utter...argh pains me to say it....BS I think. I'm not trying to attack these guys but...there seems to be no logical explanation on why FSX would affect how the ADF behaves. The default FSX behaviour certainly isn't swinging side to side 30+ degrees. Go fly the default King Air. Tell me what it does when you select an NDB. It seems we can't have best of both worlds. We can either have a technically perfect (but not completely realistic) ADF ala: FSX default a/c...or some "fancy" representation of one. You know, I typically keep my mouth shut with these type of things and leave the activism to the more passionate flight-sim-anista's out there but it drives me mad when somebody calls PMDG out on something and they get the whole aloof official response....or nothing at all. Whatever. Just tell us you don't want to fix/adjust the ADF implementation - which is the truth. Or not? Just tone down the swinging. You had to do something to cause it, so it's not impossible to revert it. I know one can lecture me/us on the whole song & dance on custom gauge programming...running things outside the FSX engine etc etc...and things aren't that easy (neither is fixing real ADF's either.)... You guys do great work and it would take a lot more then this to leave a real sour taste in my flight-simming mouth but come on...

[HiFly 16]

+1

[i. cruz 0]

I have done some NDB procedures with the default airplanes as well, obviously the ADF doesn't oscillate as much as the NGX ADF does.Still, i believe that if PMDG could do something about it they would have done it. They wouldn't want this important equipment to be this inaccurate. ADF is one of the basic requirements for IFR.

[HiFly 16]

No other high-end commercial products that I have tested exhibit this behavior: Super 80, PMDG B744, CLS DC10, Concorde FX, Level D 767, etc. If it were an FSX related phenomenon, then why has it not been an issue with these other products? Granted, PMDG did state that they are not using the FSX software engine, but that is all the more reason to conclude it is THEIR programming glich!

[Scott434 12]

I submitted a ticket about this and this was Paul's answer. "This is actually an FSX issue in the way that the ADF behaves. Unfortunately not much we can do to settle it down." - Paul Gollnick, PMDG Team

If that is indeed correct, I believe Mr. Gollnick must have made a "cut and paste" error when responding to you. I have a feeling that such a basic and trivial thing will be eventually corrected.

[i. cruz 0]

It would be nice if a PMDG member could talk about this subject more extensively.So that we can all understand about it a bit better.

[c402_cvs 0]

If that is indeed correct, I believe Mr. Gollnick must have made a "cut and paste" error when responding to you. I have a feeling that such a basic and trivial thing will be eventually corrected.

I cannot recall the default C172 doing that. Will go check sometime but I'm sure I did my IF prep on FSX with a default plane. Might have been FS9, cannot really remember. It's easy to check anyhow. Also think that might be a misquote.

[i. cruz 0]

I cannot recall the default C172 doing that. Will go check sometime but I'm sure I did my IF prep on FSX with a default plane. Might have been FS9, cannot really remember. It's easy to check anyhow. Also think that might be a misquote.

It's not a misquote, that's for sure. I got the exact statement made by Paul Gollnick.