There has been only one other runway incursion this decade at the Bay Area's three major airports that rose to the level of May's incident at San Francisco International Airport, according to the Federal Aviation Administration.

Like the near-collision May 26 at SFO, an episode at San Jose Airport in 2001 was hazardous enough for the FAA to deem it Category A, said FAA spokesman Ian Gregor.

The incident involved two small single-engine planes and occurred when an aircraft controller cleared one to land on a runway where the other was preparing for take-off, Gregor said. The planes came within 15 vertical feet.

FAA records indicate there have been no Category A incursions at Oakland International Airport this decade, though there were six less serious incursions.

Category A incursions are defined as collisions that are narrowly averted through extreme action. Category B incursions involve a significant potential for collision, while Category C events are occurrences in which pilots have ample time and distance to avoid a crash.

Events that fall into Category D, the fourth class, are those where there is little chance of collision.

SFO had 15 runway incursions between 2001 and 2007, none of them more serious than Category C. San Jose has witnessed 12 this decade.

All but two — the Category A in 2001 and a Category B in 2004 — were rated Category C or lower.

Staff writer Aaron Kinney can be reached at (650) 348-4302 or at akinney@sanmateocountytimes.com.