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David_Nelson
07-18-2007, 08:44 AM
Hi All,

I'm considering an ADI Pilot II to be coupled to a GRT Horizon I along w/ a Garmin 430.

- From the docs, it seems that if there isn't any GPS signal going to the ADI Pilot II, that the indicator will always display '0'. I infer from this that if ATC instructs me to turn to course 190 I must have a valid GPS signal to the ADI Pilot II in order to adjust the lower right knob for the correct course. Correct?

- If the GPS signal does fail, then the ADI Pilot II is nothing more than a fancy wing-leveler w/ alt hold and pitch/bank info, correct?

- Can the GRT unit translate magnetometer data to GPS "track data" and send that to the ADI Pilot II?

- The docs also indicate that Pin 17 can interpret GPSS signals. Does it in fact have GPSS capabilities? If it does, does this mean it has an ARINC429 interface? If it does not have an ARINC429 interface, does this mean that the GRT unit must translate the ARINC429 data from the Garmin 430 then send that down the serial line?

- Will this hardware configuration be able to navigate to/from a VOR? If not, what would be needed?

Thanks,
/\/elson
Austin, TX
RV-7A

n5lp
07-18-2007, 08:59 AM
...I infer from this that if ATC instructs me to turn to course 190 I must have a valid GPS signal to the ADI Pilot II in order to adjust the lower right knob for the correct course. ...If we deal with ATC we really need some basic information to fit into the system and I am being repetitive, I know. We need to have airspeed information in knots. Sometimes ATC asks us our speed and that is what they want to know. What does the airspeed read in knots. And 140 knots and 140 mph are significantly different.

If ATC says turn to 180, they are not telling us what ground track to fly, they are telling us what heading to fly and that can be significantly different also. We need something in our airplanes that will give us heading information.

In over 40 years of flying I have NEVER had ATC ask me to fly a certain ground track.

frankh
07-18-2007, 09:42 AM
This would be odd at least.

The Pictorial pilot (I know different instrument but I believe the ADI was meant to be an upgrade of the PP) always displays ground track. Now maybe its getting its track onfo from the 430 ...To be honest I have never run the PP without the 430 running as well...I'll try it out today.

But anyway, I thought the PP had its own magenetic do-dah that gave its own heading info?

Either way at least with the 430 turned on the PP will always display track and you have the option of engainging the the AP in either NAV or GPS mode...The nav mode simply displays the track, to change direction you simply twist the knob.

Because I want the ability to immediatly respond to ATC giving me a new vector, I always run the PP in NAV mode, thus a quick twist f the knob gives the new angle...I.e if it says 030....when you twist it to 050, the numbers change first and then the airplane turns at slightly below standerd rate.

Hope this helps.

As I have a Dynon with a magnetometer I never needed the PP to work independant of the 430...

Frank 7a

David_Nelson
07-19-2007, 07:48 AM
Hi Larry,

I hadn't thought about that when ATC gives a heading that it's magnetic and the GPS only knows about track. The 430 does allow my to configure it to use true north or to compute magnetic variance, however. But that doesn't compensate for any cross winds, etc. So I guess I still have to look at the GRT (or something else) for heading info.

Thanks,
/\/elson

David_Nelson
07-19-2007, 08:06 AM
This would be odd at least.

But anyway, I thought the PP had its own magenetic do-dah that gave its own heading info?

Frank 7a

Hi Frank,

And the ADI does have an internal DG. The sales literature says "GPS slaved solid-state DG" and "Direction is an electronic DG showing track". I guess TT has disabled the display of the DG.

The PP glossies say that it has a 'Magnetic Backup Mode". Reading through the docs of the PP, it specifically mentions that it has an internal magnetometer - this looks to be the missing link in the ADI. Yes, the ADI has an electronic DG, but w/o a magnetometer, it has no idea which way it's pointed. And this makes sense since we have to adjust our gyro DG against a compass.

It would be nice if TT would update the 'Product Information' matrix with all of their product offerings so that a quick side-by-side comparison could be made.

Thanks,
/\/elson
RV-7A - Fuselage and trying to wrap my head around what gizmos do what...
Austin, TX

pierre smith
07-19-2007, 09:36 AM
In over 40 years of flying I have NEVER had ATC ask me to fly a certain ground track.

Yes and no. When you're given a heading by ATC and comply, they really are looking for a ground track. You'll realize this when the give you an initial heading of 180 deg and shortly after you hold that they come back and give you 190. The reason is more than likely your drift in a crosswind.

One easy way to avoid all those extra requests from ATC is to turn your DG to match your track on the GPS. This way you'll always be doing what they request. I learned this on my last Instrument proficiency test. You can also turn to the same track by using GPS information instead of the heading indicator.

Regards,
Pierre

n5lp
07-19-2007, 09:47 AM
Yes and no. When you're given a heading by ATC and comply, they really are looking for a ground track. You'll realize this when the give you an initial heading of 180 deg and shortly after you hold that they come back and give you 190. The reason is more than likely your drift in a crosswind.Yes, they are looking for a track but they don't tell us what it is. On a day with significant wind you will most likely only get adjustments if the controller hasn't been on shift very long. After a while they will "get the wind" and do a good job of issuing you the heading, the first try, that will get the track they are after.

I still don't think we should try to circumvent that and do something other than what we are told to try to get the results we think they are after.

I expect that one day we will just be given ground tracks to fly. Probably easier for everyone with the equipment just about everyone has now.

HT1
07-19-2007, 10:23 AM
One easy way to avoid all those extra requests from ATC is to turn your DG to match your track on the GPS. This way you'll always be doing what they request. I learned this on my last Instrument proficiency test. You can also turn to the same track by using GPS information instead of the heading indicator.


Pierre, you definately never want to adjust your DG to match your GPS track. Controllers only use magnetic heading for vectors. An example of a problem doing this would be a controller putting you on a parallel heading with another aircraft at the same altitiude. The GPS track could put you on a converging course with the other aircraft who is using magnetic heading when normally you would be flying parallel.
I agree that using a track is a better way of vectoring, but until all aircraft are required to have GPS track capability we will just have to do it the old fashioned way.

John_RV4
07-19-2007, 12:53 PM
Harry,
You're point is well taken. However, with the inherent inaccuracy of a bouncing wet compass used to set your DG, do you really know what heading you're flying ? How about the guy on the "parallel" track ?

If ATC asked you to fly a course, you could fly a course exactly and so could the guy on the parallel track.... FWIW.

John

HT1
07-19-2007, 03:34 PM
John,
I agree with you 100% that vectoring aircraft with a GPS track is much more accurate than a wet compass or a DG that is kept in sinc with it. But, the problem is that there is no requirement for aircraft to have the equiptment to fly a GPS track and some can't.

The problem starts when you mix one aircraft flying a GPS track that is not being affected by the upper winds and another aircraft flying a magnetic heading that could be blown off course by 30 degrees or more.

The main point is that everyone needs to be doing the same thing or things could get real dangerous.

Fly Safe.