ADS-B Shenanigans?

Thank you for printing in Augusts magazine the short letter I wrote, highlighting an issue I encountered just south of the Albany, N.Y., Class C airspace-a Cub showing an ADS-B altitude of 500 feet below sea level. (By the way, I passed the same Cub today at very close range. This time he wasnt showing up at all on ADS-B). In your response, you asked readers to report other anomalies, so heres one from a week or so ago.

Editorial Staff

Tuesday, October 01, 2019 at 12:00 AM ET

Verified

Key Takeaways:

A pilot reported multiple ADS-B data anomalies, including erroneous altitude and extreme groundspeed readings, consistently observed in the same geographic location, suggesting a potential issue with the local ground station's data interpretation.
The article highlights the critical impact of runway slope on aircraft takeoff and landing performance, referencing historical aviation research.
The author developed a series of free, open-source "POH Performance" apps that calculate adjusted takeoff and landing distances for sloped runways, utilizing established formulas and conservative safety factors.

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Thank you for printing in August’s magazine the short letter I wrote, highlighting an issue I encountered just south of the Albany, N.Y., Class C airspace—a Cub showing an ADS-B altitude of 500 feet below sea level. (By the way, I passed the same Cub today at very close range. This time he wasn’t showing up at all on ADS-B). In your response, you asked readers to report other anomalies, so here’s one from a week or so ago.

I was in nearly the exact same location as I was for the prior report when my ADS-B In/Out transceiver, a Garmin GTX 345, highlighted an aircraft passing low overhead at a speed of 1033 knots. I eagerly acquired it visually, assuming it was a UFO. (There has been a spike in UFO sightings recently—I was hoping to report the first one with ADS-B compliance!)