FALLS CHURCH, Va. – Defense conglomerate General Dynamics Inc.’s fourth quarter earnings surged 20 percent, buoyed by a particularly strong performance in its aerospace business, the company said Wednesday.

For the three months ending Dec. 31, the company earned $336 million, or $1.66 per share, compared with profits of $279 million, or $1.40 per share, a year ago.

Analysts surveyed by Thomson First Call had predicted earnings of $1.63 a share.

In morning trading Wednesday, General Dynamics shares rose $1.50, or 1.5 percent, to $100.27 on the New York Stock Exchange. The stock has traded in a 52-week range of $84.96 to $109.98.

Quarterly revenue was up 10 percent, from $4.7 billion in the year-ago quarter to $5.2 billion.

Only the company’s Marine Systems unit saw a slight slip, with a 1 percent drop in revenue and stagnant earnings of $51 million in the current quarter and the year-ago quarter. The division includes Maine’s Bath Iron Works and Connecticut’s Electric Boat.

“In three out of four of our major business groups, earnings and operating margins increased dramatically over the year-ago period,” Chief Executive Nicholas Chabraja said in a statement. “In the Aerospace group, Gulfstream had tremendous order activity in the fourth quarter.”

The company advised investors that it expects earnings per share to increase by 11 to 13 percent in 2005.

The Falls Church-based company employs more than 70,000 people worldwide.