In a 24 Feb incident an American Eagle turboprop took off over the top of a Continental Airlines jetliner crossing the far end of its departure runway. The turbo- prop got airborne about 3,500 feet from where the jetliner was and passed over it at about 800 feet. The AMASS radar system warned of an impending runway collision just before the turboprop left the ground, reinforcing the known fact that its alerts are always too late for ATC to issue deconflicting instructions.

24 hours later a Skywest turboprop was sent around from late finals when an AMASS alert warned of an encroaching aircraft invading the landing runway. That Sunday incident was on the Southern side of LAX, where twice last year aircraft had come within 100 feet of colliding.

The FAA is investigating the incidents but hasn't yet pronounced on their level of severity. The agency has however tentatively classified both as runway incursions -- separation breaches in which aircraft get uncomfortably close to each other. LAX had eight incursions last year, with the last one occurring in late September.