By Zoe Sottile, CNN
(CNN) — Denver International Airport is conducting a safety analysis after a person who jumped over a fence into a runway was struck and killed by a plane during takeoff late Friday.
The fatal incident has drawn scrutiny to the airport’s security protocols – and highlighted the challenges of securing a facility twice the size of Manhattan.
The pedestrian, who has not been identified, was killed just two minutes after they jumped a perimeter fence and crossed a runway at the airport. The pilots of the Frontier Airlines Airbus, which was headed to Los Angeles, quickly aborted takeoff. Twelve people were injured during the incident.
Surveillance video taken before the collision shows a blurry figure – tiny in comparison to the jet and the expanse of land around them – standing on the runway.
Then the figure is overtaken by the plane, engulfed in flames.
“We’re stopping on the runway,” a pilot said, according to audio from ATC.com. “We just hit somebody. We have an engine fire.”
The airport said it would “perform an incident analysis and after action in the coming days which will include reviewing the ongoing investigation, including our perimeter security program.”
There are 36 miles of perimeter fence at the airport, according to its statement, and staff perform continuous inspections.
Denver International Airport is the nation’s third busiest by passengers, behind only Atlanta and Dallas-Fort Worth.
And it’s massive: At 53 square miles, the airport is larger than San Francisco, according to its website.
That makes securing its facilities a challenge, according to experts.
“The more expansive the land area of an airport, the more perimeter to defend, the more remote areas, and the more complex terrain, all of which provide more opportunities for unauthorized entry,” explained William Rankin, an adjunct professor at Florida Institute of Technology who researches airport management and safety.
Still, pedestrian incursions are extremely rare, Rankin said. Publicly available data shows there are just a handful of pedestrian incursions – between zero to five – each year on average, he said.
Fatal pedestrian-aircraft collisions like Friday night’s are even rarer, happening less than once per year on average, he said.
The incident “was an extremely rare event and should not make the public less confident in the security of the major US airports,” Rankin said.
Past security breaches
As rare as pedestrian incursions are, this isn’t the first time someone has breached a perimeter fence at the Denver airport.
Eight people – including both pedestrians and drivers – breached the fence between 2004 and 2015, an investigation by The Associated Press found.
At the time, an airport spokesperson said, “We believe many folks do not realize they are even on airport property — it looks like farmland and a breach may be miles and miles away from a runway or the terminal.”
The AP found 268 perimeter breaches across the country during the same period. They span from intentional stowaways to seemingly accidental trespassing. The Denver incidents included a drunk 28-year-old who drove through a perimeter fence and a man who climbed the fence and said he was on his way to work, according to the Denver Post.
FAA dat