Mystery reigned Tuesday morning as an aircraft flew crazily above the Minneapolis-St. Paul airport like a spider on LSD.
The Learjet, commonly geared toward wealthy private owners, didn't have a call sign, and circled the airport for several hours, making distinctive arcs across the runway. Information usually displayed on flight tracking services, such as the plane’s registration number, didn’t show up.
Some people thought it might have been an FBI surveillance jet. These low-flying planes, according to the Star Tribune, have been spotted circling specific locations in Minneapolis and St. Paul. Others invoked Ted Cruz’s conspiracy theory that the plane was busy spreading chemicals full of mind-control drugs.
Still others suggested offered a less exotic explanation. The Learjet was nothing but a flight check plane, which the Federal Aviation Administration uses for routine testing of on-field navigation equipment during off-hours. And they would be correct, according to air traffic control audio of that morning.
Liveatc.net keeps an archive of transmissions. Around the time the Learjet was pissing off the night owls, the pilot is recorded having this conversation with an air traffic controller:
Pilot: “The request is to begin flight inspection arcs on the runway four localizers.” (Radio beacons planes use for navigation.)
ATC: “[Indistinguishable] runway four, 10-mile arcs?”
ATC: “And do they go all the way around the airport?”
Pilot: “No they’re just across the localizer six miles, either side of center line. And we can get anywhere between 2,300 and 5,300 feet.”
Mystery solved. FAA spokeswoman Elizabeth Cory explained that the jet had to swoop low over the field to test the instruments, and that it would have repeated that over different runways throughout the night.