Intruders breached security fencing around Sky Harbor International Airport more than authorities disclosed, according to an Associated Press investigation.
In all, there were 21 perimeter security breaches from 2004 through mid-February at Phoenix's airport, many involving fence jumpers.
There were two breaches in 2014 and three in 2015. Meantime, the airport increased security patrols. There was one more in January.
Nationally, breaches remain as frequent as ever, and are happening on average every 10 days at one of the 31 airports AP studied.
Airports say perimeter defenses are strong and note that none of the 345 breaches AP documented involved a known terrorist plot.
When AP began scrutinizing the outer defenses of airports nationally, Phoenix authorities searched their records and documented 12 breaches.
Through a long-running Freedom of Information Act request, AP received federal records that showed another five the airport didn't tell AP about. A Phoenix police spokesman said the department had no record of those breaches.
Most of the newly uncovered breaches -- which happened in 2010, 2009, 2007 and 2004 -- involved people jumping fences. So did the majority of the three breaches in 2015 and one in 2016.