The gyrocopter that was about to make a big splash with an unannounced landing on the lawn of the Capitol appeared on radar as a tiny dot as it made its way south from Gettysburg.

Nobody noticed.

The various and complicated reasons that a pilot who wanted to deliver a political message to Congress was able to fly into Washington’s protected airspace unnoticed until seconds before he landed were spelled out Wednesday by seven federal officials who appeared before the House Oversight and Government Reform Committee.

In the aftermath of the April 15 incident, one of the questions raised was why no one — neither NORAD nor the Federal Aviation Administration nor the Secret Service — picked up on the fact that an aircraft was about to fly past the White House and head for the Capitol.

The best explanation Wednesday came from FAA Administrator Michael Huerta, whose agency operates the primary radar system. He said air-traffic controllers filter their radar so they can distinguish the planes they’re supposed to direct from lots of other things in the sky — flocks of birds, balloons, moving weather systems.

Even with that filter, there are unidentified items that appear as small dots on the radar screen. On April 15, the gyrocopter flown by Doug Hughes was one of them. After he landed, the FAA took a look at its raw radar data.

“Mr. Hughes’s gyrocopter appeared on our radar as one of those small dots, indistinguishable from all other non-aircraft,” Huerta said.

He said the dot appeared on radar intermittently, suggesting that the gyrocopter dipped behind mountains, tall buildings or the tree line from time to time as it made its way from an unmanned public airstrip in Gettysburg.

The FAA shares its unfiltered radar images with other federal agencies, including the Defense Department and NORAD. Deputy Assistant Secretary of Defense Robert G. Salesses and NORAD’s Adm. William E. Gortney both made unrevealing opening statements but promised to get into greater detail if the committee reconvened behind closed doors.

Secret Service Director Joseph Clancy said his agents interviewed Hughes as early as 2013 but didn’t know his object was coming their way until a guard at the White House looked up to see the gyrocopter fly by.

“While the Secret Service received telephone calls on the date of the incident, at no time was information provided in that call that would have alerted our personnel that Hughes was piloting his aircraft to the Capitol,” Clancy said.

U.S. Capitol Police Chief Kim Dine said his department received an e-mail from a Tampa Bay Times reporter at 12:59 p.m. inquiring whether permission had been granted for a flight to the west Capitol lawn.

One minute later, Dine said, the reporter called saying he wanted to confirm that the Secret Service and Capitol Police had given permission for a gyrocopter to land. The reporter was told no permission had been given, he said.

“No mention was made that the landing was imminent,” Dine said.

Hughes, 61, was arrested as soon as the rotors on his gyrocopter stopped turning. Capitol Police sent in a bomb-sniffing dog, a robot and, finally, officers in bomb-disposal gear to examine a box strapped to the gyrocopter. It contained letters calling for reforms in campaign finance laws that he wanted delivered to members of Congress.

A day later, still facing criminal charges, Hughes was released and sent home to Florida. He was ordered to remain in his bungalow in Ruskin until a preliminary hearing May 8.