A pilot who was flying erratically over Sonoma County Tuesday night and failed a field sobriety test after he landed at the Petaluma airport is now facing flying operating an aircraft under the influence of alcohol and other charges.

CHP said the case was unlike anything they've ever seen.

On Tuesday, the CHP told KTVU it was flying a patrol plane over Highway 37 near Infineon Raceway at around 4 p.m. when the two officers spotted the plane.

"He rolled the aircraft almost completely inverted. [It] didn't roll all the way over, but rolled inverted and rolled back. Did it three times," said CHP pilot Jim Andrews.

The plane was an Aero Trek, a model that is not authorized for aerobatics. The Highway Patrol said at times the plane was flying as low as 50 feet off the ground, getting dangerously close to freeway traffic.

62-year-old Michael Ferrero of Penngrove was initially of accused of flying recklessly. CHP administered the field sobriety test on Ferrero right after he landed when officers detected the odor of an alcoholic beverage on his breath.

"We're very fortunate he didn't cause any crashes on the roadway," said Andrews.

Pilot Jeff Domich also spotted the same plane.

"Normally, you'll see guys doing clearing turns or other safety maneuvers prior to doing aerobatics and this guy was kind of all over the place," Jeff Domich.

Federal Aviation Administration regulations prohibit pilots from drinking eight hours before flying.

Cases where pilots are charged with actually operating aircraft while under the influence are unusual, though just last November a former United Express pilot was sentenced to six months in prison from a 2009 incident when he was caught trying to fly after drinking.

"This is very unusual for us. I've been here 10 years in the air ops unit and I've never seen it," said Andrews. "Anytime somebody goes and does something like this it reflects badly on all of us."

In addition to the flying under the influence and reckless flying charges, Ferrero will likely face penalties from the FAA which could include suspension or even revocation of his pilot's license.

Ferrero told the Santa Rosa Press Democrat had a celebratory whiskey after landing the Aerotreck A220 two-seater that caused him to fail the sobriety test.

The Penngrove resident also said he has hundreds of hours of experience flying low over open country such as the pasture he skirted Tuesday.