My altitude encoder has a known discrepancy with my altimeters of +100 ft. This is actually within allowed tolerance, but it causes a couple of issues:
1. When using altitude pre-select or ALT hold, I set the autopilot 100 ft. higher than desired. e,g, set 8100 ft to level/hold 8000 ft.
2. When flying at a given assigned altitude (with or without AP engaged) ATC will see me as 100 ft. higher than assigned.
The latter has sometimes resulted in real-time "discussions" with ATC. Last Sunday while departing Pearson field (Vancouver, WA) beneath the PDX Class C as PDX tower insisted I was at 900 when I reported at 800.
ATC in-air "discussion"
Moderators: Rick, Lance Murray
- Rich
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ATC in-air "discussion"
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
- Diamond_Dan
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Re: ATC in-air "discussion"
At least for my encoder, the Sandia SAE5-35, there is a straightforward procedure for adjustment. It's best done in conjunction with the 24 month transponder check, which tests the correlation of the Density Altitude being broadcast with the altimeter(s). There are a couple of buttons accessible from the side of the unit to do this. I've just kind of lived with it, since it's technically within spec (+/- 125 ft with the primary altimeter) and fully repeatable and constant offset at all altitudes. My recheck isn't due for a few months but I'm thinking I'll get it done earlier to avoid these annoying in-flight discussions.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
- Rich
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Re: ATC in-air "discussion"
This excerpt from the Sandia manual shows the adjustment buttons that need tweaking:
Here's how one gains access to these things in my plane. A challenge to say the least:
Disclaimer: Diamond has produced a number of different instrument panel designs over the years so the location and even the encoder model in mine might not be the same as others.
Here's how one gains access to these things in my plane. A challenge to say the least:
Disclaimer: Diamond has produced a number of different instrument panel designs over the years so the location and even the encoder model in mine might not be the same as others.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
- Steve
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Re: ATC in-air "discussion"
Rich is correct on the mounting and model variability. Mine has a Trans Cal encoder, which is not adjustable, and is mounted in an equally inaccessible area…