In a major boost to its sprawling satellite-making operation in El Segundo, Boeing Co. announced that it won a $1.1-billion U.S. Air Force award that will preserve high-paying engineering jobs in Southern California and bolster smaller firms that supply parts for the massive satellites.

The deal was the fourth big-money satellite contract for Boeing in two years — a reversal of fortunes from the dog days of the late 1990s — and it keeps the production line humming at a time when the state is facing a 12% unemployment rate.