WASHINGTON (CNN) -- The National Transportation Safety Board has released dramatic animation of two runway near-collisions this year to illustrate what the agency says is the need for improvements in runway safety.
The NTSB animation shows two planes nearly colliding at the San Francisco International Airport in May.
The first animation shows a Delta Air Lines Boeing 757 and a United Airlines Airbus A320 coming within 230 feet of colliding on the runway at the Fort Lauderdale-Hollywood International Airport in Florida in July.
The re-creation was based on radar and flight data recorder information from the planes involved.
The animation includes audio from the air traffic controller, who can be heard yelling, "Stop, stop, stop!" to the United plane as the Delta aircraft attempts to land. Watch animation, hear controller's pleas »
The second animation shows a May incident at San Francisco International Airport in California in which a Republic Airlines jet takes off, coming within 35 feet of a SkyWest Airlines commuter turboprop that has just landed.
There were no injuries in either situation.
The videos were shown Thursday during the NTSB's annual "most wanted transportation safety improvements" board meeting, where the agency reviews its greatest concerns in transportation safety.
The Federal Aviation Administration reported that serious runway incursions were reduced by 25 percent in 2007, but the NTSB said much work remains on runway safety and systems to notify pilots when they are about to collide with another plane or vehicle.
NTSB Chairman Mark Rosenker expressed frustration with the slow progress of implementing new technology, such as the use of a global positioning system-type procedure in cockpits that would help warn pilots of dangers on the runway.
Rosenker told the NTSB-only panel, "It is time to do something before we have to investigate an accident that is catastrophic."
Among the most wanted transportation safety improvements cited on the NTSB's Web site are items to "stop runway incursions/ground collisions of aircraft" with the notations "action needed by Federal Aviation Administration" and "unacceptable response."
The site says systems the FAA has added to airports to warn air traffic controllers of potential collisions aren't "sufficient."
"In recent incidents, [one system] did not alert controllers in time to be effective, and the situations were instead resolved by flight crew actions that sometimes bordered on heroics or just plain luck," the NTSB site says. "Until there is a system in place to positively control ground movements of all aircraft, with direct warning to pilots, the potential for this type of disaster will continue to be high."
Rosenker told Thursday's board gathering that "this must be resolved."
"We've had this recommendation for a number of years -- too many number of years," he said.
Other areas of NTSB concern include fuel tanks on airplanes, pilot and air traffic controller fatigue, and technologies that could help prevent automobile collisions. E-mail to a friend
CNN's Eric Fiegel contributed to this report.