Today started with a new aircraft crossing 15 flights in Compare: a Cessna 172 Skyhawk. A four-seat single-engine plane, on final approach to Lisbon, sixteen times, at 140 knots and 95 dB. It did not add up.
It was an easyJet Airbus A320neo. Every aircraft broadcasts a permanent radio address, and public registries still linked this one to a small private Cessna in Austria. We found four more cases the same way: an easyJet A321neo listed as a microlight, an ASL Boeing 737 freighter and a Maltese airliner listed as light twins, and a WestJet 737 MAX filed as a Cessna 177. Matching the exact minute of our captures with Flightradar24 gave us their real identities. Their types are fixed, and the station now ignores a registry that puts a small private plane behind an airline callsign.
Then a quieter lesson. At 16:56 a TAP A321neo passed overhead at 88 dB, but the station logged only background noise. It was still watching the INEM medical helicopter that had just left, and missed the airliner by thirty seconds. From now on it looks at every aircraft in range, not just the last one it heard. The continuous recording kept the true values, so this flight and fourteen similar ones since September are corrected.
And one for the human ear. An ATR turboprop was recorded at 102 dB. I was on the terrace and heard nothing like that. The continuous log agreed with me: 88 dB, with one impossible jump in the middle. Corrected, and a new check now flags any peak that leaps too far above the seconds around it.
Also today: a question from Alessandro in Milan about why our noise levels swing from one day to the next. The answer was the wind. Landings pass low over the terrace, take-offs pass higher, and the runway follows the wind.
A good day for the data, mostly thanks to things that did not look right.