Ricky_231 Posted March 14, 2020 Report Share Posted March 14, 2020 I guess I shouldn't be surprised - yet here we are. Often when in cruise, long straight leg, autopilot ON, I'll rest my left hand on the dashboard. I'm tall, and there aren't that many places to rest your arm in the cockpit. I few times I've noticed that my HSI is a little off (+/- 10 degrees) in straight level flight when compared to the compass. So I'll adjust it. Today, after ATC called me out because I was off course (they'd given me a heading), I spent a good 5 minutes fighting the HSI - I'd adjust it, and 10 seconds later it'd be 10 deg off. I'd adjust it again, and it'd be off again. Then I saw it. Every time I adjusted the HSI, I had my hand down, on my lap/yoke as I leaned forward to read the compass. Once adjusted, I'd put my hand back on the dash. And every time I did that, the compass would swing10 degrees or so. So I brought my hand closer to the compass: enjoy the video. The effect is so strong that even sitting back, with my hand close to my chest, moving my arm up and down will swing the compass. I guess I'll go back to my mechanical watches when flying. IMG_3246.MOV 1 Quote Link to comment Share on other sites More sharing options...
toto Posted March 14, 2020 Report Share Posted March 14, 2020 I'm not sure if there's a good way to mitigate this, but I've definitely seen it with phones and tablets in the cockpit. I try to keep them as far away from the whiskey compass as possible. Metal-bodied devices seem worse than plastic, but all have some effect. Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 14, 2020 Author Report Share Posted March 14, 2020 20 minutes ago, toto said: I'm not sure if there's a good way to mitigate this, but I've definitely seen it with phones and tablets in the cockpit. I try to keep them as far away from the whiskey compass as possible. Metal-bodied devices seem worse than plastic, but all have some effect. Yeah I had noticed it with my phone and I keep it far away. But it's not as strong as with the watch - I can pull up my phone and move it around near my face and it won't do anything to the compass. Quote Link to comment Share on other sites More sharing options...
toto Posted March 14, 2020 Report Share Posted March 14, 2020 Just now, Ricky_231 said: Yeah I had noticed it with my phone and I keep it far away. But it's not as strong as with the watch - I can pull up my phone and move it around near my face and it won't do anything to the compass. Interesting. I wear an A-Watch too, but my left hand is almost always on the yoke or in my lap, and it never occurred to me that that was close enough to cause interference. I'm going to test this on my next flight and see if it does the same thing for me... Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 14, 2020 Author Report Share Posted March 14, 2020 5 minutes ago, toto said: Interesting. I wear an A-Watch too, but my left hand is almost always on the yoke or in my lap, and it never occurred to me that that was close enough to cause interference. I'm going to test this on my next flight and see if it does the same thing for me... I'd be interested to know the results. My watch is the cellular/SIM equipped version - not sure that has anything to do with it, but to keep it "scientific" :-) 1 Quote Link to comment Share on other sites More sharing options...
MikeOH Posted March 14, 2020 Report Share Posted March 14, 2020 4 minutes ago, Ricky_231 said: I'd be interested to know the results. My watch is the cellular/SIM equipped version - not sure that has anything to do with it, but to keep it "scientific" :-) Can you disable the cellular/SIM portion and see if the interference is reduced/goes away? Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 14, 2020 Author Report Share Posted March 14, 2020 11 minutes ago, MikeOH said: Can you disable the cellular/SIM portion and see if the interference is reduced/goes away? I believe so. I'll try doing that next time. 1 Quote Link to comment Share on other sites More sharing options...
EricJ Posted March 15, 2020 Report Share Posted March 15, 2020 It's weird that these days the compass may be one of the less reliable navigation instruments due to stuff like this. For folks that get a chance to install one, the modern magnetometers seem to be far more stable and since they're mounted away from the cabin and other things, are less susceptible to this sort of thing. The main redeeming quality of the compass seems to be that it requires no power. Quote Link to comment Share on other sites More sharing options...
Yetti Posted March 15, 2020 Report Share Posted March 15, 2020 I carry one of these. hard to read in a moving environment, but pretty reliable. Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted March 15, 2020 Report Share Posted March 15, 2020 Maybe I’ll try putting mine in theater mode and see if that affects it. Quote Link to comment Share on other sites More sharing options...
Tahir K Posted March 15, 2020 Report Share Posted March 15, 2020 I wonder if this has the same effect on glass based cockpits? I wear one as well and did a lot of my training with the G1000 suite and never noticed this issue. However, seeing your video and the big change it causes is definitely concerning. Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted March 16, 2020 Report Share Posted March 16, 2020 11 hours ago, Tahir K said: I wonder if this has the same effect on glass based cockpits? I wear one as well and did a lot of my training with the G1000 suite and never noticed this issue. However, seeing your video and the big change it causes is definitely concerning. Most of the time the magnameter is mounted in the tailcone, so shouldn’t have much effect on glass. Although, if you have a whiskey compass you can still mess with that. 1 Quote Link to comment Share on other sites More sharing options...
Ragsf15e Posted March 16, 2020 Report Share Posted March 16, 2020 On 3/14/2020 at 6:18 PM, Yetti said: I carry one of these. hard to read in a moving environment, but pretty reliable. Hold that thing in your hand with your Apple Watch on your wrist and you’re gonna be very reliably off course! 2 Quote Link to comment Share on other sites More sharing options...
Yetti Posted March 16, 2020 Report Share Posted March 16, 2020 (edited) 9 hours ago, Ragsf15e said: Hold that thing in your hand with your Apple Watch on your wrist and you’re gonna be very reliably off course! luckily I never bought into the Apple overpriced hype. Guess I could test my FitBit and see if it is TSO compliant :-) Since I have a vertical card compass it would be interesting to see if it has the same issue. I was surprised that the vertical card compass needs the vibration from the plane to work properly. Edited March 16, 2020 by Yetti 1 Quote Link to comment Share on other sites More sharing options...
GeeBee Posted March 16, 2020 Report Share Posted March 16, 2020 Just re-swing your compass and check the box, "Apple Watch ON". 1 Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 16, 2020 Author Report Share Posted March 16, 2020 1 hour ago, Yetti said: luckily I never bought into the Apple overpriced hype. Guess I could test my FitBit and see if it is TSO compliant :-) Since I have a vertical card compass it would be interesting to see if it has the same issue. I was surprised that the vertical card compass needs the vibration from the plane to work properly. It does - I tested it on a friend's plane on Saturday. In flight. 1 Quote Link to comment Share on other sites More sharing options...
lotsofgadgets Posted March 16, 2020 Report Share Posted March 16, 2020 Do you have the millanese loop band on your watch. That has a magnet in it. Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 16, 2020 Author Report Share Posted March 16, 2020 3 minutes ago, lotsofgadgets said: Do you have the millanese loop band on your watch. That has a magnet in it. nope - nylon sports band. and my watch is the cheap aluminum case version - not the stainless steel one. my guess is that it's the all the radios built in on it - bluetooth, wifi, cellular, NFC, and maybe the battery itself. Quote Link to comment Share on other sites More sharing options...
59Moonster Posted March 16, 2020 Report Share Posted March 16, 2020 Seeing as how unreliable those are, wouldn't it make more sense to set your HSI to your GPS? Quote Link to comment Share on other sites More sharing options...
Hank Posted March 16, 2020 Report Share Posted March 16, 2020 19 minutes ago, 59Moonster said: Seeing as how unreliable those are, wouldn't it make more sense to set your HSI to your GPS? Approaches, and course instructions from ATC, are based on Magnetic headings. What your GPS delivers is Desired Ground Track, not the same thing; if it's windy enough, then it is Very not the same thing! Quote Link to comment Share on other sites More sharing options...
KB4 Posted March 16, 2020 Report Share Posted March 16, 2020 On 3/14/2020 at 4:28 PM, Ricky_231 said: I guess I shouldn't be surprised - yet here we are. Often when in cruise, long straight leg, autopilot ON, I'll rest my left hand on the dashboard. I'm tall, and there aren't that many places to rest your arm in the cockpit. I few times I've noticed that my HSI is a little off (+/- 10 degrees) in straight level flight when compared to the compass. So I'll adjust it. Today, after ATC called me out because I was off course (they'd given me a heading), I spent a good 5 minutes fighting the HSI - I'd adjust it, and 10 seconds later it'd be 10 deg off. I'd adjust it again, and it'd be off again. Then I saw it. Every time I adjusted the HSI, I had my hand down, on my lap/yoke as I leaned forward to read the compass. Once adjusted, I'd put my hand back on the dash. And every time I did that, the compass would swing10 degrees or so. So I brought my hand closer to the compass: enjoy the video. The effect is so strong that even sitting back, with my hand close to my chest, moving my arm up and down will swing the compass. I guess I'll go back to my mechanical watches when flying. IMG_3246.MOV Guess FAA needs to update their Compass Errors in include "i-errors" 1 1 Quote Link to comment Share on other sites More sharing options...
jlunseth Posted March 17, 2020 Report Share Posted March 17, 2020 I am curious. Do you have the KFC200 system in your aircraft with the slaved 525A HSI? If so, why would you adjust the HSI? Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 18, 2020 Author Report Share Posted March 18, 2020 On 3/17/2020 at 11:56 AM, jlunseth said: I am curious. Do you have the KFC200 system in your aircraft with the slaved 525A HSI? If so, why would you adjust the HSI? Century 41 with century NSD360A slaved HSI. The NSD360 doesn't have a fast slave function on startup - so you need to set it to the compass before going. Then it'll self adjust (SLOWLY). I might have, once or twice on a VFR flight, taken off without setting the card and then had to adjust it in flight. As a result of having made that mistake before, I always double check the HSI when I'm level. Most of the time it's perfectly aligned. Sometimes it isn't - and I (erroneously) attributed the error to maybe my not checking or aligning the HSI perfectly on the ground (like I said, it's 5-10 degrees off). So I'd slap myself on the back of the head, and adjust the card while thinking "I'm sure I checked... but here's the evidence you didn't". In hindsight, I now realize all these times the HSI was a little off, was during longer cruise legs, and I believe it had to do with me and big idiot hand on the dash and the mother of all electromagnets on my wrist apparently. Quote Link to comment Share on other sites More sharing options...
Ricky_231 Posted March 18, 2020 Author Report Share Posted March 18, 2020 On 3/17/2020 at 11:56 AM, jlunseth said: I am curious. Do you have the KFC200 system in your aircraft with the slaved 525A HSI? If so, why would you adjust the HSI? But regardless of what you have onboard, if you check your HSI in straight level flight and it's off wouldn't you adjust it? and then try and figure out why, but first of all, make sure that the instrument you're relying on to fly a heading is consistent with the magnetic compass (that should, in theory, be the most reliable source of that information in the cockpit). Quote Link to comment Share on other sites More sharing options...
jlunseth Posted March 18, 2020 Report Share Posted March 18, 2020 That's why I asked. You can push the slaved button and adjust the HSI all you want with the KFC200 system, but the minute you hit "Slaved" it goes back to whatever input the flux gate is giving it. In other words, there is no point in adjusting it. The adjustment only applies with the KFC200 if you are flying in "free gyro" mode. The KFC200 manual seems to say it can be adjusted if slave mode does not appear to be reading correctly, but that is not how it actually works. At least in my aircraft, the compass is the least accurate. Before that comes GPS information, which may be a little off because of wind crab, but way better than a compass. I don't know how your system works though. Quote Link to comment Share on other sites More sharing options...
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