AIR FORCE ACADEMY, Colo. (AP) _ Nate Beard ran for 45 yards and two touchdowns and Air Force forced two fourth-quarter turnovers in a 27-13 victory over Navy on Saturday.

Air Force (4-1) committed a season-high 12 penalties and was held 172 yards below its rushing average but made big plays defensively to get a leg up in the race for the Commander in Chief's Trophy.

The trophy travels between Air Force, Army and Navy, depending on which school beats its two service academy rivals. Air Force has won the trophy nine times in the last 11 years.

Navy (0-5), off to its worst start since 1994, got as close as 17-13 on a 45-yard field goal by David Hills late in the third quarter before Air Force began controlling the clock with fullbacks Beard and Scott Becker.

Becker accounted for 33 yards on a 38-yard drive that set up David Adams' 40-yard field goal 2:38 into the fourth, and Beard took over following a fumble by Navy quarterback Ed Malinowski 37 seconds later.

Beard carried eight times for 22 yards and capped a nine-play, 36-yard scoring drive with a 1-yard TD run that gave Air Force a 14-point lead with 7:21 left.

Navy, which has lost 17 of 19 to Air Force, promptly drove to the Falcons' 38 before the threat ended when Malinowski was forced into an errant pitch recovered by C.J. Zanotti with 5:21 remaining.

Malinowski, who took over for ineffective starter Brian Broadwater in the second quarter, completed 8 of 16 passes for 81 yards, and Cee Harris scored Navy's only touchdown.

Beard's 3-yard TD run helped Air Force to an early 7-3 lead, but the Falcons committed two costly penalties that sparked Navy during a 17-play scoring drive in the second quarter.

Air Force received a personal foul when Chad Rogers was called for roughing the punter on fourth-and-21, and a defensive holding penalty gave Navy another first down after an incomplete pass on third-and-15.

The Midshipmen took advantage as Harris scored on a 5-yard run with 7:36 left before halftime. It was Navy's fourth touchdown of the season and first in eight quarters.

Air Force responded on the ensuing drive, thanks in part to a tipped pass that turned into a 61-yard catch by Ryan Fleming. Mike Thiessen scored from the 1 on the next play.

The Falcons took a 17-10 lead into the half after Adams kicked a 38-yard field goal set up by a blocked punt, Air Force's fifth blocked kick in three games.