A combination of technology and personnel dedicated to making air travel safe has created a system that makes it all but impossible for a gun to slip through the Transportation Security Administration’s screening and onto a plane.

But it has happened.

On Oct. 21, Jeff Wilson, a Republican state senator from Washington State boarded a plane at Portland International Airport with his wife for the first leg of a five-week vacation in Southeast Asia.

Carry-on bags were screened again when passengers changed planes in San Francisco for the flight to Hong Kong, according to investigators.

Halfway through the trip, Wilson reached into his bag for a pack of gum. He discovered his pistol was inside.

The TSA said it is reviewing video surveillance from the airport and images from screening equipment as part of its investigation into how the gun made it onto a plane undetected.

Wilson was arrested and charged with possession of an unregistered firearm after notifying customs officials about the gun when the plane landed in Hong Kong.

He told authorities that he packed quickly and failed to check the contents of his bag. The gun was registered in Washington, and Wilson has a permit to carry a concealed firearm.

A judge in Hong Kong acquitted Wilson after an Oct. 30 hearing, The Associated Press reported.

In January, a man was traveling from Nashville to Raleigh when a TSA agent spotted a gun in his bag that previously was missed by screeners.

Musician Cliff Waddell told authorities he was shocked the gun was in his bag because he flew with the same bag the day before and it was not detected.

He told investigators he didn’t know how the gun got in the bag because he keeps it locked in the glove compartment of his car. He later realized that he took the gun out when the vehicle was taken to a shop for repairs, the AP reported.

While Waddell took responsibility for failing to keep track of his gun, he said he is worried about how the TSA could have missed something so significant.

In June 2022, the TSA launched an investigation to determine whether a gun was missed during screening at a checkpoint in the Hartsfield-Jackson International Airport, The Atlanta-Journal Constitution reported.

Authorities said they were doing a secondary review of images made of bags that already passed through TSA screening that showed a firearm may have been missed, the newspaper reported.

The agency said it searched the terminal for the passenger with the carry-on bag but were not able to find them.

In November 2021, a TSA screener at Hartsfield-Jackson Atlanta International Airport spotted a gun in a passenger’s bag, according to the AP.

When the officer opened the suitcase, the man reached for the gun and it went off.

The passenger, a 42-year-old convicted felon named Kenny Wells, grabbed the 9 mm semi-automatic Smith & Wesson and managed to escape from the airport by blending in with other passengers who were fleeing the scene.

Authorities reported that several passengers and staff members were injured during the sudden evacuation, including a woman who struck her head after falling down the escalator and a Delta Airlines agent who was trampled.

In May, Wells was sentenced to 10 years in federal prison for illegal possession of a firearm by a convicted felon.

In 2022, more than 6,500 guns were seized from the 853 million passengers who were screened by TSA before boarding an airplane.

Aviation security officials believe the majority of guns being carried by passengers are being stopped by screeners, but they are still concerned about even one gun making it onto a plane.

In February 2022, the U.S. House Subcommittee on Transportation and Marine Security conducted a hearing chaired by U.S. Rep. Bonnie Watson Coleman, D-N.J., to address the surging number of firearms at TSA checkpoints, according to a transcript.

In her opening remarks, Coleman said it was “good news” that “TSA has a talented workforce and top-notch technologies. But the bad news is that it only takes a single gun slipping through for tragedy to ensue. The deadly consequences of a hijacker bringing a loaded firearm on a plane are not difficult to imagine.

“Even when TSA successfully interdicts a weapon, transportation workers and the traveling public face dangers,” she said. “Just a few months ago in Atlanta, a passenger accidentally discharged his firearm at a checkpoint, resulting in chaos, injuries and flight delays.”

Coleman recounted a January 2017 incident in which five people were killed and six others were wounded at Fort Lauderdale-Hollywood Airport when a man opened fire on passengers who were standing in a baggage claim area.

The case illustrates that even when a gun is transported properly, its presence in an airport can pose a danger to the public, she said.

Former Army reservist Esteban Santiago pleaded guilty to the shooting and was sentenced to life in prison, according to the Miami Herald.

He was accused of packing the weapon in a gun case and declaring it on his flight from Alaska to Florida. When he arrived, he claimed the case, went into a restroom to load the gun and came out shooting.

Two months before the shooting, Santiago was briefly hospitalized for psychiatric care after he went to the FBI office in Anchorage and told agents he was hearing voices telling him to support the Islamic State terrorist group.

He also told agents the CIA was pressuring him to watch training videos, the Herald reported.

Agents referred Santiago to Anchorage police, who took his handgun from him while he underwent a psychiatric evaluation for a few days.

The gun was returned in December, and Santiago used it in the airport attack, according to the newspaper.

Coleman said during the hearing that the rising number of guns detected in airports places transportation workers and the traveling public in danger.

“The increase in unruly passenger incidents alongside the increase in firearms injected into the aviation environment make for a toxic combination,” she said. “We need to explore a range of solutions to keep guns off planes and away from the TSA checkpoints.

“This should not be a partisan issue. This is not about gun control but about aviation security. We must all stand together in support of keeping loaded pistols off planes.”

In addition to higher fines, violators should be required to attend gun-safety classes, said Balram Bheodari, general manager of Atlanta’s main airport. He also suggested that Congress consider placing violators on the federal no-fly list until they complete safety training along with suspending them from quick-screening programs such as PreCheck.

Atlanta’s Hartsfield-Jackson had more guns detected than any other U.S. airport in 2022.

Coleman also questions the legitimacy of so many people using the same excuse when they are caught and doesn’t think it should give them a pass from facing consequences.

“It’s hard for me to believe that everybody that gets caught … forgot they had it,” she testified. “And even if they did forget they had it, it’s still an illegal act and we need to treat it as such.”

In the wake of the hearings, the TSA increased fines from $13,910 to $14,950 and agreed to revoke PreCheck eligibility for five years when a person is caught with a gun.

The congressional hearing also noted that additional efforts to improve airport security were enacted at the nation’s airports following the Nov. 1, 2013, shooting death of TSA Officer Gerardo Hernandez, 39, at Los Angeles International Airport.

Hernandez was greeting passengers and checking travel documents when a gunman opened fire, killing him and wounding several other people.

Coleman said the increase in the number of guns being seized at airports should be a signal seen for authorities to be proactive in coming up with solutions.

“If and when something unthinkable happens, we can hardly act surprised,” she said. “It simply should not take a tragedy, whether it is a hijacking or an accidental discharge that claims a life, to trigger action.”

Tony LaRussa is a Tribune-Review staff writer. You can contact Tony by email at tlarussa@triblive.com or via Twitter .