A man killed himself by walking in front of a Frontier flight at Denver International Airport. How common are these security breaches at Denver's airport?

DENVER — Six trespassers have breached the fence around Denver International Airport since 2023, culminating in the May crash with a Frontier Airlines flight that killed a person who scaled the security fence and walked onto a runway, police records show.

In one of those cases, a man crashed through a perimeter fence gate, causing more than $2,000 in damage as he drove onto the airfield, according to records obtained from the Denver Police Department. In another, a man jumped the fence after crashing his car nearby and was found sitting on an active taxiway at about 6:40 a.m. A third fence-hopper told police he was trying to walk to Texas.

Airport safety experts say the number isn’t immediately alarming. While incidents may appear to be happening more frequently, it’s likely a matter of better detection and increased reporting, said Annmarie Heth, an assistant professor of aviation and aerospace sciences at the Metropolitan State University of Denver.

Heth has worked in the aviation industry since 2009, spending years as both an airport operations manager in Florida and a flight coordinator for a Colorado flight school.

Fatal incidents like the May crash that killed Michael Mott are extremely rare, Heth said. Advanced technology means security can usually catch trespassers before something bad can happen, she said.

“Fences are there to keep honest people out,” Heth said. “If somebody is really intent on getting through a fence, they’re going to get through.”

Mott, 41, scaled DIA’s 8-foot, barbed-wire-topped security fence and walked onto a runway shortly before 11:20 p.m. on May 8. He was struck and killed by a Frontier plane accelerating for takeoff, and Denver Chief Medical Examiner Dr. Sterling McLaren ruled his death a suicide.

Mott’s breach of the airport security fence was unusual, but not the airport’s first encounter with trespassers, according to police records.

Since January 2023, Denver police officers have responded to six cases of people breaching the airport perimeter fence, including the fatal May crash, and two trespassing cases in which people jumped the boundary fence into the airport’s warehouse area, police records show. The earliest incident in 2023 occurred in September, according to those records.

At least two of the airport’s eight trespassers had active arrest warrants at the time of their breach — one for a failure to appear in Denver court on a traffic charge and one for motor vehicle theft, according to the probable cause statements.

The report for the incident resulting in Mott’s death was not yet available because the case remains under investigation.

DIA officials declined to comment on the trespasses.

It’s difficult to know how DIA’s perimeter breaches compare to the rest of the country because airports all report trespassing incidents differently and there’s no national database, Heth said.

But the Federal Aviation Administration does keep track of runway incursions at airports with traffic control towers, including DIA, according to the agency.

Incursions boil down to planes, vehicles and people being in the wrong place at the wrong time. According to the FAA, incursions include air traffic control errors that don’t leave enough space between planes and obstacles on runways or that clear aircraft to take off from or land on closed runways; pilot actions that violate federal aviation regulations, like crossing runways without clearance; and pedestrians or vehicles entering airport runways or taxiways without authorization.

Of the 19,482 airports in the United States, 527 have air traffic control towers, according to the FAA. Just over 5,100 of those airports are public, and more than 14,300 are private.

Roughly 5,890 runway incursions were reported at airports with air traffic control towers between January 2023 and June 2026, according to quarterly totals from the FAA’s runway incursion database. Of those, 1,022 involved unauthorized pedestrians or vehicles entering the airfield.

Only two of the incidents documented by police at DIA during that time appear in the FAA’s database. A total of 37 incidents involving unauthorized vehicles and pedestrians at the Denver airport show up in the database, dating back to April 2006.

The Denver Police Department has a dedicated Airport Police Bureau at DIA “with officers at the ready to swiftly respond to emergencies and safety issues,” police spokesman Doug Schepman said in a statement.

“The Airport Police Bureau works closely with Airport Operations at DEN and monitors operational data, and the bureau adjusts resources when trends are identified,” Schepman said. “This is the same approach the Denver Police Department takes in its citywide operations.”

The FAA and National Transportation Safety Board declined to comment on DIA’s perimeter fence breaches.

“Trespassing doesn’t necessarily equal a security failure,” Heth said. “The fact that we’re talking about these right now often means that the system worked. The alarms were activated, the airport operations center sent out law enforcement and they responded.”

When Heth worked as an airport operations manager at Pensacola International Airport in Florida, a position she held from 2009 to 2015, she said a gust of wind was enough to set off the warning sensors and launch an investigation into the potential trespasser.

Now, alarms and cameras are more sophisticated, and it’s much easier to catch fence jumpers before anything bad happens, she said.

“We’ve got better analytics, better technology, an improved reporting culture and better training with our airport employees,” Heth said. “I don’t think that it’s anything alarming or dramatic.”

Still, Heth said it’s important that airport officials look at each incident and learn from it, “closing any vulnerabilities” that may have made it easier for people to enter the secured airfield.