Today, Rhodes, 61, a nuclear engineer who lives in Gresham, keeps a two-seater plane he built himself at the Troutdale Airport, 10 miles east of Portland along I-84. He's logged more than 2,000 hours flying—always conscientious about safety for himself and his passengers.

But Rhodes says he and hundreds of other pilots who regularly use Troutdale, the state's third-busiest airport, now fear for their safety. 

“What they want to do,” Rhodes says, “will make flying in an out of Troutdale dramatically more dangerous.” 

The “they” posing the threat, Rhodes says, is the airport’s owner, the Port of Portland. 

The port wants to sell 38 acres directly north of the Troutdale Airport to the developer of a natural gas-fired power plant. The proposed plant, called the Troutdale Energy Center, would create a powerful heat updraft that experts say could endanger small planes flying in and out of the airport. 

That development is currently the subject of a permitting dispute pitting the state's Energy Facility Siting Council, which issues permits for new electrical generating plants, against a coalition of environmentalists and aviation groups, including the Oregon State Aviation Board and groups representing airplane owners and pilots.

"I understand the port wants to maximize revenue from the real estate it owns," says Rhodes, "but developing this power plant is detrimental to another part of the port—and to pilots."

Port spokeswoman Kama Simonds says the developers of the Troutdale Energy Center conducted extensive safety modeling that assured the port of the project's safety.

"The port believes that the Troutdale Energy Center and the Troutdale Airport can successfully coexist," Simonds says.

There's some irony in the port finding itself at loggerheads with pilots and the aviation board. Airports are the cash cow for a port with grim financial challenges elsewhere. 

Labor disputes have cost the port its marine container business. That has left the port even more focused on Portland International Airport, whose landing fees and parking revenues are the agency's lifeblood.  

The port is also in the real estate and economic development business. It bought the contaminated site of a shuttered Troutdale aluminum plant in 2007. Selling part of it to the Troutdale Energy Center (for an undisclosed price) would allow the development of the reclaimed industrial land. 

The Troutdale Airport, with its 5,400-foot runway, typically handles small planes, although private jets also land and take off there. Flight instructors have moved operations to Troutdale from Hillsboro, the state's busiest airport. The two airports will generate about $3.5 million in revenue for the port this year, most of that from Hillsboro. 

Although the smaller airports generate only a tiny fraction of PDX's revenue, they play a vital role in the port's system. The port depends on the Hillsboro and Troutdale airports to handle small aircraft that would otherwise need to use PDX. The smaller airports handle 50 percent more takeoffs and landings than PDX while providing training grounds for domestic and international pilots. 

Initially, pilots worried that a power plant at Troutdale would hamper visibility. Gas-fired generating plants work by boiling water to produce steam that drives turbines. When the water is cooled, the steam roiling out of the plant's cooling towers could fog pilots' flight paths and create a hazard.

But the bigger concern now is heat.

Earlier this year, the Federal Aviation Administration directed Troutdale users to an independent consulting firm to analyze the potential impact of the invisible plume of hot air that the combustion of gas by the plant would produce. 

"You're putting a known but invisible hazard right into the path that pilots using Troutdale must fly," says Mary Rosenblum, a Canby resident and president of the Oregon Pilots Association. 

Rosenblum says modeling shows the plume could suddenly lift one wing and flip a plane upside down.

“This would happen when the plane is 1,000 feet or less off the ground,” Rosenblum says. “At that altitude, you cannot recover.” 

The FAA consultant's initial analysis in March found that the invisible plumes could cause as many as a dozen planes to lose control and crash annually—with fatal consequences. A second run of the same model earlier this month found it could happen even more often.

Risk modeling done for the Troutdale Energy Center in 2013 found no such danger.

Rhodes scoffs at that earlier analysis. The nuclear engineer—who spends his days calculating the proper dosages of radiation for cancer patients—has reviewed the modeling and says the proposed power plant represents "a clear and present danger” to pilots. 

"Engineers and mathematicians work hard to 'average out' calculated risk for their clients," Rhodes said in written testimony. "I'm an engineer. I know how the system works. Don't kid yourself, cherry-picking data to support a client's position happens all the time."

The FAA regulates only physical structures, such as towers or smokestacks that exceed 500 feet, not plumes. 

But in January, the federal regulator issued guidance on hot air plumes. 

"The FAA has determined that thermal exhaust plumes in the vicinity of airports may pose a unique hazard to aircraft in critical phases of flight (particularly takeoff, landing and within the pattern)," says an FAA memo to airport managers dated Jan. 21, 2015, "and therefore are incompatible with airport operations."

That warning would seem to give pause to the Port of Portland, which owns the land where the generating plant would be built, and to the state energy siting council, which in 2013 gave tentative approval to the plant's location next to the Troutdale Airport. 

Todd Cornett, an assistant director for the Oregon Department of Energy responsible for staffing the siting council, says his agency's staff recommended proceeding with the project after concluding it met all the criteria for locating a power plant.

The group financing the Troutdale Energy Center, Energy Investors Funds, builds plants all over the country—not without incident. In 2010, a plant in Middletown, Conn., similar to the one proposed for Troutdale, blew up during early testing, killing six people and resulting in a $16.6 million fine by the Occupational Safety and Health Administration—the third-largest in OSHA history. A spokesman for TEC didn't return WW's calls.

The pilots' safety concerns about the Troutdale plant come on top of environmental worries about the pollution the plant would emit. 

The conservation group Friends of the Gorge opposes the plant. And the U.S. Forest Service, which enforces the Columbia River Gorge National Scenic Area Act, says locating a power plant at the western gateway to the gorge is a bad idea. 

Agency officials say pollutants emitted from the plant would block views in the gorge and endanger sensitive plant species.  

The new safety study and the environmental concerns are part of an ongoing contested-case hearing over the permitting of the power plant. Opponents to the site forced the hearing, in which both sides will make their best case for or against the safety and environmental effects of the plant. 

Rhodes says he'll be "stunned" if the state siting council proceeds with approval of the plant after the new risk study. Even if someone raises additional information affirming the plant's safety, he adds, the burden of proof still rests on the applicant. 

"State agencies are supposed to work on behalf of the people of Oregon, not an applicant," Rhodes says. "In this case, they are working in the licensees’ interest. That’s a direct conflict of interest.”