Doug Hughes loves to fly. As a kid, he’d plant himself at the local airport and monitor the comings and goings of planes. He read up on the Wright brothers and Kitty Hawk.

On Wednesday, Hughes, a 61-year-old mailman from a small town on Florida’s Gulf Coast who dearly wants campaign finance reform, flew his fragile little ultralight gyrocopter through some of the most closely protected airspace on the planet and landed it on the West Lawn of the U.S. Capitol. He called it Project Kitty Hawk.

He announced his plans on the Internet and in his hometown newspaper. He said he felt compelled to do what he could to halt corruption in the nation’s capital. He attached a big U.S. Postal Service insignia to the aircraft fuselage, loaded it onto a trailer last Friday, and drove north. He would not go postal, but rather airborne, to deliver 535 letters to members of Congress urging them to tighten the rules on money in political campaigns.

“I have no intention of hurting anyone,” Hughes wrote on his Web site, the Democracy Club, which carries the motto, “Because We the People own Congress.” “There is no way I can prevent overreaction by the authorities, but I have given them as much information and advance warning as my fuel supply allows.”

The warning didn’t help. Air defense systems did not detect the copter as it entered restricted airspace above Washington, according to a North American Aerospace Defense Command spokesman. No one tried to stop the gyrocopter, which sounds like a lawnmower and looks like a flying bridge chair.

The contraption that landed on the Capitol’s West Lawn

Air Force Maj. Jamie Humphries, a NORAD spokesman, said the authorities are investigating why NORAD was not made aware of the gyrocopter until after it had landed on the Capitol grounds.

“We are trying to determine the why, but I can say we did not scramble assets,” he said.

The U.S. Secret Service denied late Wednesday that anyone had tipped off its Tampa field office to Hughes’s intentions. Secret Service spokesman Brian Leary said that in October 2013, “a concerned citizen” told the agency about someone who wanted “to land a single manned aircraft on the grounds of the United States Capitol or the White House.” Leary said Secret Service agents in Florida interviewed Hughes the next day and conducted “a complete and thorough investigation.” The agency did not say it did anything about Hughes after 2013.

Mapping three flight restriction areas in the region.

In a statement, a Federal Aviation Administration spokeswoman, Laura Brown, said that Hughes “was not in contact with FAA air-traffic controllers and the FAA did not authorize him to enter restricted airspace.” Private aircraft are prohibited from flying over Area 56, the name aviation officials give to a swath of the District’s federal core stretching from the White House east to Stanton Park in Northeast Washington.

The FAA said that any pilot who flies in that area at an altitude below 18,000 feet “without prior coordination and permission . . . may face civil and criminal penalties.”

“I don’t believe that the authorities are going to shoot down a 60-year-old mailman in a flying bicycle,” Hughes said in a video that appeared on the Tampa Bay Times Web site shortly before he landed. “I’m defenseless. . . . A Boy Scout with a BB gun could shoot me down.”

Hughes took off from a location that he described only as being “over an hour away from the no-fly zone,” but which turned out to be the Gettysburg Regional Airport, about 80 miles away. He landed with a little bounce on a broad expanse of grass at the foot of Capitol Hill. He sat still inside his open-air cockpit for about a minute, whereupon U.S. Capitol Police surrounded the copter and then detained and arrested Hughes.

Unexpected show on Mall

Although the guardians of the nation’s airspace did not see the mailman coming, some D.C. residents did.

Jose Labarca, 55, was sitting on the Mall at about 1:50 p.m. when he spotted the aircraft about 35 to 40 feet in the air, heading east toward the Capitol.

The chopper, Labarca said, “looked totally official” with its Postal Service logo. “I thought, the Postal Service has helicopter service to the Capitol now?” Labarca said the pilot appeared to be wearing a mailman’s uniform. “When he flew by us, he gave us a thumbs up,” he said.

Elizabeth Bevins saw the chopper land as she walked alongside the Reflecting Pool below the Capitol. “I assumed it was some sort of police system,” she said. “But then I saw the other police and realized it was someone doing something crazy.”

“No sane person would do what I’m doing,” Hughes said in the Tampa Bay Times video. “I’m not suicidal.” He also said he is not a terrorist, noting that “terrorists don’t announce their flights before they take off.”

Although Hughes, a silver-bearded man with a quiet manner, said he had no desire to die in his demonstration, he told the Times that he was first inspired to take extreme protest measures after his son committed a gruesome public suicide.

On an August night in 2012, John Joseph Hughes, 24, drove west into the eastbound lanes of a major highway near Orlando, turned off his headlights, and hit the accelerator until he slammed into an oncoming vehicle. Hughes killed himself and the other driver, a 66-year-old man. Police said the younger Hughes had been distraught after arguing with his girlfriend and had told her he planned to kill himself.

About a year ago, after Doug Hughes published his plan on his Web site, a Secret Service agent in Florida questioned both Hughes and a friend of his, Mike Shanahan, the Times reported. Hughes told the agent that he did own a gyrocopter, which he kept at a small airport in Wauchula, Fla., and that he had been planning a dramatic gesture to focus attention on campaign finance reform. Hughes told the agent he was not planning to crash his copter into any buildings.

The Times said the same agent visited Hughes’s workplace, the post office in Riverview, Fla., a couple of days later and asked co-workers about him. But there was no further contact from the Secret Service, Hughes told the newspaper.

The Times account of Hughes’s plans, which included video footage shot about a week ago, was published less than an hour before he landed.

“It worked, looks like,” tweeted Ben Montgomery, the Times reporter who wrote about Hughes, shortly after the landing. “Can’t believe he made it.”

Montgomery flew up from Florida to be on the scene; he said in an interview that his newspaper was “comfortable reporting this story knowing . . . that the authorities did know about this, even if they didn’t know when exactly he was going to pull it off.”

Jennifer Orsi, managing editor of the Times, said in a statement that the newspaper called the Capitol Police and the Secret Service about an hour after Hughes took off from Gettysburg, and about 30 minutes before he landed.

“We feel we did the right thing,” said Neil Brown, editor of the Times. “He told the authorities what he was going to do. We decided to be full-blown observers on it.” Brown said no government agency has complained about the paper’s actions, though the Secret Service called Wednesday afternoon to say “they may want to talk to our reporters.”

Montgomery, who said he had expected Hughes to be shot down, described Hughes as a “mix of P.T. Barnum and Paul Revere.”

Patrick Hughes, the pilot’s brother, said: “The actions he has taken are those of his own making and choosing. . . . But if you get a chance to talk to him, I am sure he will have lots to say.”

‘A voter’s rebellion’

Hughes, who was spurred to political activism by the Supreme Court’s Citizens United decision striking down limits on campaign donations by corporations and unions, wrote on his blog that he hoped his “special delivery” stunt would “change the narrative” and bring voters together to insist on “honest government. . . . Corruption in Washington, D.C. has robbed the U.S. citizens of the representative government that is our birthright.”

The letters Hughes was carrying said he was “declaring a voter’s rebellion.”

The mailman provided a live chat function on his blog, and readers used it to embrace his act. “God bless this man,” someone wrote. “We need the corruption to stop!”

“More fuzz on his stones than most people for sure,” wrote another. “How do we join up!”

Postal Service officials refused to comment on Hughes’s employment, saying only that the service’s inspector general was “in contact with postal management on this issue.”

Hughes, who is married and has a 12-year-old daughter, did not need a pilot’s license to fly his gyrocopter. The rudimentary aircraft dates to the 1920s and was one of the first aircraft to use overhead rotating blades to lift off the ground. Unlike helicopters, a gyrocopter’s overhead blades are not powered by an engine. Rather, a smaller blade powered by a motor at the front or rear of the aircraft pulls or pushes it forward. That momentum causes the overhead blades to turn, lifting the aircraft off the ground.

“They are kit-built by their owners, and many are classified as ultralights,” said Chris Yancey of the Alexandria, Va.-based Helicopter Association International. “With a five-gallon tank, it could fly for, maybe, an hour.”

In 2003, a tobacco farmer drove his tractor from North Carolina to Washington, parked it in a pond on the Mall, and threatened to blow it up, causing a traffic nightmare and a security scare that lasted 47 hours.

A D.C. federal court jury convicted the farmer, Dwight Watson, of making false threats and destroying government property. District Judge Thomas Penfield Jackson sentenced Watson to six years in prison, noting that “the sentence I will hand down to you today is intended to deter the next nice guy who thinks he has a legitimate complaint.”

Two hours after Hughes landed, a bomb squad found nothing harmful on the gyrocopter and police moved it to “a secure location.” An hour after that, streets were reopened to earthbound traffic.

As of Wednesday evening, no congressional office reported having received Hughes’s letters, each of which carried the proper postage.

Lori Aratani, Paul Duggan, Paul Farhi, Mary Pat Flaherty, Ashley Halsey III, Carol D. Leonnig and Mark Lieberman contributed to this report.