The spring 'poop rain' remains a mystery, as Angie Craig pushes for an investigation

Barbara McNabb couldn't quite fathom what she was seeing that April morning. A brown substance had coated her blue SUV while it was parked overnight at a Bloomington hotel, and every other car in the lot was covered with dried gunk as well.

"It was like someone took a hose and sprayed every single side of my car," said McNabb, who had been staying at a hotel near Minneapolis-St. Paul International Airport while the floors were being refinished in her Burnsville home.

McNabb drove to the car wash and moved on, not knowing she was about to become part of an unfolding mystery — as yet unsolved — that touches on urban myth, science, aviation and U.S. Rep. Angie Craig, who represents the south metro suburbs in Congress.

Could it be a bird, a plane, or a superhero with a continence problem? Craig wanted to get to the, uh, bottom of it all.

Five constituents in all reported similar incidents to her last spring involving so-called "poop rain" — fecal-like matter showering down from the skies, possibly from aircraft above.

The reports varied. McNabb, for example, said the brown matter she encountered didn't smell like feces. "At first, I thought it was mud," she said.

That wasn't the case with Carisa Browne, whose car was pelted with gobs of brown liquid on May 12 while she was waiting at a Caribou Coffee drive-thru in Burnsville with her 6-year-old son.

"It was like the weight of heavy raindrops, but all at the same time, and my car was covered in brown," Browne told the Star Tribune at the time. "I was like, 'Oh my god, what just happened?' "

Like McNabb, Browne initially thought it might have come from a large flock of birds. But when she opened her car window, she said the smell was unquestionably poop-like — as in human excrement.

Call for investigation

After learning about Browne's experience, Craig dashed off a letter to Billy Nolen, who was acting administrator of the Federal Aviation Administration (FAA), and demanded an investigation, given the proximity of MSP to her district. What safety measures, if any, she asked, are in place to prevent such incidents?

"My constituents have the right to live their lives without the threat of sewage getting in their coffee," she wrote Nolen.

Craig took to social media to note her district's fecal misadventures and her follow-up with federal authorities. It attracted the usual partisan ire, but some just couldn't help themselves; one person speculated the matter came from Russian astronauts in the space station, while others made snarky comments about Burnsville.

An FAA official — not Nolen — replied to Craig nearly three weeks later, saying they hadn't received a complaint about Browne's "event" and don't track "complaints associated with lavatory leaks." The official noted it's up to aircraft operators to address septic tank leaks, but assured Craig that the FAA would investigate a complaint and work with aircraft operators to "ensure they take appropriate corrective action."

Craig wasn't satisfied. "The FAA's lack of answers concerning this situation isn't cutting it for me. I'll keep pushing for more transparency here — that's what my constituents deserve," she said in an email to the Star Tribune.

"This was a disgusting incident — and one that deserves a clear explanation," she added. But one may not be forthcoming.

When contacted by the Star Tribune, the FAA reiterated that no complaint on any of the reported incidents had yet been filed. When asked how many such complaints are reported annually and where, a spokesperson advised the newspaper to file a Freedom of Information Act request.

Brown — or blue?

When the FAA receives a report about such incidents, it tries to determine whether the material came from an aircraft and then identify which one may be involved. But Jim Higgins, a professor of aviation at the University of North Dakota, said it's not exactly rocket science.

"If it's fecal matter," he said, "it's for sure coming from an airplane."

"The possibility of someone getting pelted with poop rain is very unusual," continued Higgins, a former commercial airline pilot. "The likelihood of it happening is less than somebody getting hit by a lightning strike — it's very, very seldom. But it does happen from time to time."

Others contacted by the Star Tribune seemed little interested in probing the issue of poop rain or the intimate details of airplane lavatories. Officials with the Minnesota Pollution Control Agency did not respond to an inquiry, nor did Delta Air Lines, the dominant carrier at MSP, or Boeing Co., the giant aircraft manufacturer.

A University of Minnesota spokesperson said they didn't have an expert available to discuss this kind of air pollution. And the Metropolitan Airports Commission (MAC), which operates MSP, declined to comment.

Generally speaking, lavatory waste is contained in a holding tank until an aircraft lands and is then pumped out by a ground crew. Contrary to popular myth, the pilot of the aircraft can't jettison the waste while in the air.

If the plane's tank or drain tube has a leak, some water may form ice on the outside of the aircraft. As the aircraft descends and the temperature warms, the ice can melt and fall off.

Because some lavatory waste may be treated with blue deodorizer, the plunging detritus has been given the moniker "blue ice." Reports of falling blue ice have popped up for decades worldwide, from the Netherlands to Long Island.

Blue ice has also secured a spot in pop culture. An episode of "MythBusters," a science program on the Discovery Channel, probed the urban legend of blue ice and confirmed it, with help from NASA.

The material that fouled McNabb and Browne's cars was definitely not blue. And as McNabb noted, there's a serious side to all the poop jokes.

"Environmentally, it's dangerous," she said. "Anyone could get sick from that. I didn't touch it."