Nov. 12--TRACY -- Pilots who fly into Tracy Municipal Airport soon will be seeing red -- and white.

The city is using a grant from the Federal Aviation Administration to install a Precision Approach Path Indicator system next to the airport's runway. The $35,000 system provides pilots with accurate information as they prepare to land their aircraft.

"You don't need these to land. Pilots land all the time without them," said Rod Buchanan, deputy director of Tracy parks and community services, who said the PAPI system is a safety upgrade many smaller airports would like to install.

"But they are another tool to be able to manage aircraft in the most precise manner possible."

PAPI uses four giant lights, usually mounted on the left side of a runway. Each is angled at a slightly different pitch and shines either red or white light at a pilot depending on the degree of the plane's final approach.

According to Kyle Owens, President of Sacramento-based Flight Light Inc., a pilot's preferred angle of descent is 3 degrees. If a pilot sees two white lights and no red ones on approach, the plane is coming in at too steep an angle. If the lighting is reversed, the angle is not steep enough. The optimum angle is for a pilot to see one red and one white light.

"In flying, we say, 'Red over white, pilot's delight,'"â?°" he said.

To illustrate the point, Owens said motorists may see a series of red lights as they drive past Sacramento International Airport or Stockton Metropolitan Airport indicating their cars -- which are parallel to the ground -- are riding along at less than a 3 degree pitch.