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#1
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Sticky DG and DME distance question
Couple of questions.
Went up to practice some ILS approaches. While being vectored for my approaches, my DG kept sticking through the 270 heading. First time on my initial approach and the second approach. Third and fourth approaches, DG acted normal, though seem a little off compared to the magnetic compass. (gave me good practice for partial panel approaches!). Also, my header bug seem to be frozen, couldn't move it at all. I ended up using my magnetic compass and VFR GPS for my primary navigation and tracking. I had this happen once on the ground a long time ago, and never gave any thought as it performed flawlessly in the air since. Vacuum gauge was exactly where it should be. Last thing I want to worry about in the clag is the DG. Is the DG worth overhauling or just getting a new one??? I went to http://www.aircraftspruce.com/menus/in/gyros.html to see what prices I am looking at, and it seemed all over the page in price. This would be a part obviously I don't want to cheap out on, but I don't want to buy a part that is has something in it I never will need. Suggestions much appreciated. I figured to post this time b4 going out on the limb. DME question. While on my VOR Alpha approach back to MBO, ATC reported me 3 miles from the VOR, and my DME reported me 4 miles. This is the first time I ever had a discrepancy that much. Anybody know what gives. My DME seemed correct as it reflected 5 miles to my airport. Allen |
#2
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A Lieberman wrote:
DME question. While on my VOR Alpha approach back to MBO, ATC reported me 3 miles from the VOR, and my DME reported me 4 miles. This is the first time I ever had a discrepancy that much. Anybody know what gives. My DME seemed correct as it reflected 5 miles to my airport. DME is slant range, ATC may be horizontal. How high were you? |
#3
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On Sat, 09 Jul 2005 16:11:22 GMT, john smith wrote:
A Lieberman wrote: DME question. While on my VOR Alpha approach back to MBO, ATC reported me 3 miles from the VOR, and my DME reported me 4 miles. This is the first time I ever had a discrepancy that much. Anybody know what gives. My DME seemed correct as it reflected 5 miles to my airport. DME is slant range, ATC may be horizontal. How high were you? Hi John, I was at 2000 feet, which is about 1700 AGL. Allen |
#4
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A Lieberman wrote:
DME is slant range, ATC may be horizontal. How high were you? I was at 2000 feet, which is about 1700 AGL. Certainly not enough to give you an extra mile of slant range. |
#5
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On Sat, 09 Jul 2005 16:53:57 GMT, john smith wrote:
A Lieberman wrote: DME is slant range, ATC may be horizontal. How high were you? I was at 2000 feet, which is about 1700 AGL. Certainly not enough to give you an extra mile of slant range. That was my thought in flight, in which I queried approach and asked him to verify my distance. Never noticed a problem before, and wondered if DME's can lose their accuracy. I didn't have the time to reprogram my GPS as I had to fly the plane, but if I had the time, that would have been my next step. Allen |
#6
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Allen,
I can't remember if you ave an auto-pilot or not but if oyu don't we are having a S-TEC30 installed in 3 weeks and will ahve an "extra" DG when we are done. Works fine for us now but it doesn't have a heading bug. Jon Kraus 4443H @ TYQ A Lieberman wrote: Couple of questions. Went up to practice some ILS approaches. While being vectored for my approaches, my DG kept sticking through the 270 heading. First time on my initial approach and the second approach. Third and fourth approaches, DG acted normal, though seem a little off compared to the magnetic compass. (gave me good practice for partial panel approaches!). Also, my header bug seem to be frozen, couldn't move it at all. I ended up using my magnetic compass and VFR GPS for my primary navigation and tracking. I had this happen once on the ground a long time ago, and never gave any thought as it performed flawlessly in the air since. Vacuum gauge was exactly where it should be. Last thing I want to worry about in the clag is the DG. Is the DG worth overhauling or just getting a new one??? I went to http://www.aircraftspruce.com/menus/in/gyros.html to see what prices I am looking at, and it seemed all over the page in price. This would be a part obviously I don't want to cheap out on, but I don't want to buy a part that is has something in it I never will need. Suggestions much appreciated. I figured to post this time b4 going out on the limb. DME question. While on my VOR Alpha approach back to MBO, ATC reported me 3 miles from the VOR, and my DME reported me 4 miles. This is the first time I ever had a discrepancy that much. Anybody know what gives. My DME seemed correct as it reflected 5 miles to my airport. Allen |
#7
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Regarding the DG:
Sounds like a mechanical interference issue, which could account for both the "snagging" on the 270 hdg and the bug being "frozen". The DG may only need repair rather than full overhaul. Take it to a competent instrument shop for diagnosis. If it does need overhaul, whether to do it or not, in my opinion, depends upon the quality of your unit. Some of the newer "cheapies" are not worth overhauling while older, more robust designs are. Again, a good shop should be able to advise you. Regarding the DME issue: If your DME doesn't read to tenths of miles but instead rounds to the nearest mile, the discrepancy may not exist. If the DME read exactly 3.0 miles from the VOR and ATC told you 4, that could be just a somewhat sloppy guesstimate by the controller. My understanding is that they can bring up range rings on their new screens, but if a controller is busy he/she might just "eyeball" it. In any event, I wouldn't worry too much about it. If the DME indicates distance it is most likely functioning properly. Measurement errors are conceivable but not common. Of course, as you suggest it will be simple to do a check against your GPS -- -Elliott Drucker |
#8
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john smith wrote: A Lieberman wrote: DME is slant range, ATC may be horizontal. How high were you? I was at 2000 feet, which is about 1700 AGL. Certainly not enough to give you an extra mile of slant range. You have a digital readout that gives exact distance. The controller looks at the little space between you and the VOR symbol on the radar scope. That symbol, a circle, is about a mile in diameter. The controller looks at that space and he came up with 3 miles. He was off a mile. No big deal. |
#9
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#10
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DME is slant range, ATC may be horizontal. How high were you?
I was at 2000 feet, which is about 1700 AGL. Certainly not enough to give you an extra mile of slant range. You have a digital readout that gives exact distance. The controller looks at the little space between you and the VOR symbol on the radar scope. That symbol, a circle, is about a mile in diameter. The controller looks at that space and he came up with 3 miles. He was off a mile. No big deal. Another factor is the physical location of the DME site with respect to the airport reference point. |
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