Ancestors

Toot

Written by Denis Warburton on 2025-01-01 at 00:35

I’d like to congratulate the owners of N566XL for having an aircraft which DOES NOT transmit ALTITUDE. Good work! ffs

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Descendants

Written by Denis Warburton on 2025-01-01 at 00:36

I was wondering why I had lengthy recent aircraft tracks that were showing up at 0 feet in altitude. Apparently, this is why.

The data from ADS-B craft is often… ‘amazing.’

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Written by Denis Warburton on 2025-01-01 at 00:42

… and now they’re back in the air, with their transponder sending valid altitude data….

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Written by Denis Warburton on 2025-01-01 at 01:30

To put this in the main thread, and not just in a reply…

I pulled the tracking data for this craft from my ADS-B system, and processed it to create GPX tracks.

Based on 2 prior flights, I suspect this may be a plane with an aviation school, out of KHWO.

Since it was only failing to report altitude for the first 2.5 mile leg as it approached KHWO, that may have been a (simulated) equipment failure. (Once the craft was a block or so from the airport, the altitude information returned.)

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Written by Denis Warburton on 2025-01-01 at 01:32

All that being said, this is very weird - and something I’ve not seen with any frequency before today.

I’ll have to see if there are any other irregularities in the compiled tracking data, on my RAID.

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Written by J. B. Crawford on 2025-01-01 at 01:46

@artandtechnic There are different possible configurations, including ADS-B out devices with built-in altitude encoders, but the altitude encoder is often external to the mode-C/ADSB (sometimes it's even an encoder built in to the mechanical altimeter). In some configurations turning off a glass cockpit or electronic instrument (like a G5) will cause loss of altitude since that instrument was the data source, which I could see an instructor doing.

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Written by J. B. Crawford on 2025-01-01 at 01:49

@artandtechnic Mode-C or altitude information isn't technically required, but it's required in so many scenarios that if you're near a city it probably is (class A, class B, class C, 10k or up, w/in 30nm of class B apt, tuesdays, new moons, etc). very weird how patchwork the rules have been in this area as the FAA fights between its desire to mandate mode-C and ADSB vs. the GA community that doesn't want to have to install transponders.

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Written by Foone🏳️‍⚧️ on 2025-01-01 at 00:43

@artandtechnic I'm gonna register an "aircraft" and have it always report altitude as 0.

because it's a boat.

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Written by Foone🏳️‍⚧️ on 2025-01-01 at 00:43

@artandtechnic if the number of feet/meters above sealevel ever changes from zero, something bad has happened

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