Craig Ulmer

Blimp Tracking

2016-09-18 planes

Close, but no blimp data. Last Thursday at my son's soccer practice, one of the Goodyear Blimps circled the field as it descended for a landing at the Livermore Airport. It was a little surreal, since it looked like the blimp was monitoring the practice the same way it circles big bowl games. However, blimp sightings aren't that uncommon out here. Livermore is on the fringe of the Bay Area and we have a large municipal airport with wide open spaces around it. It seems like the perfect place to launch, land, and park a blimp if you knew you were going to be visiting the area by dirigible airship.

Sunday morning I started wondering where the blimp was going while it was in the area. Since I've been running a dump1090 data logger on my Edison board for the last few weeks, I began pulling the data and parsing it for signs of dirigibles. As I was puzzling through how I might identify a blimp in the pile of points, I heard a faint buzzing sound coming from outside and realized that the blimp was at that very moment passing by my house.

Getting the ID From Dump1090

I went over to the webpage that dump1090 generates to see what aircraft were in the local area. I was disappointed to see that the map was pretty much empty nearby, which meant that the blimp wasn't transmitting position data. I looked at the list of planes and noticed that there were some planes in the area that were reporting their presence, but not identifying their position. I sorted them by altitude and found one that was cruising along at only 2,000ft with an ICAO hex ID of A4A7EF. Some searching around and I found this ID belongs to tail N4A, which is a 33-year-old (!) blimp owned by Goodyear.

Looking it up in FR24

While I was disappointed that my own logger didn't get any position info for the blimp, I knew that other aviation sites have tracks for aircraft based on other data sources. I looked it up on FlightRadar24 and found that they had logged a few flights for the blimp on Saturday:

Well, that solves the mystery: they were out here to watch Stanford play against USC (for the people back home, that's U of Southern California, not South Carolina). They circled that stadium for more than 5 hours, trying to make sense out of the whole situation. Then they went and blew some steam off in San Francisco. I'd like to think that the highlight of their trip though was watching my son's soccer team practice.