Raytheon Co., the No. 3 U.S. defense contractor, warned for a second time in two months yesterday that sales and profit in 1999 and 2000 will be less than forecast because of delayed orders and increased competition.

The Lexington, Mass.-based company will take pretax charges totaling $638 million this year and a $30 million charge next year to close plants, shed assets and write down investments.

The company did not detail the scope of its cutbacks. Raytheon is a leading local employer, with about 5,000 workers in units in Arlington, Vienna and Lanham.

Raytheon also said sales of its flagship Patriot missile will suffer from competition from other manufacturers of similar systems.

Raytheon now expects total sales to grow 3 percent this year and next, half its earlier forecast.

Raytheon's shares plunged 44 percent to end the day at $24.25, their biggest one-day drop in at least two decades.

The root of Raytheon's problems was planted four years ago, when the company began an acquisition spree that totaled more than $15 billion. Now chairman and chief executive Daniel Burnham, who joined the firm after the acquisitions were undertaken, said Raytheon didn't have the management in place to combine all those defense businesses.

"You have a consistent lack of knowledge of what's going on in their own business," said Brad Erwin, an analyst with Banc One Investment Advisors, which sold most of its Raytheon shares after the Sept. 16 profit warning. "Their comments are so inconsistent with the conversation of two or three weeks ago."

Burnham told analysts in a conference call that the computer systems at the various businesses weren't programmed to produce the information needed to track the business.

Last month, Raytheon said the charges would be as much as $450 million in the third quarter. The increased charge estimate and the second warning have analysts wondering if Raytheon management has a grip on all its problems.

"This doesn't speak well for the credibility of management," said Shawn Narancich, an analyst with D.A. Davidson & Co.

Raytheon now expects this year's per-share profit to range from $2.70 to $2.80 excluding charges, compared with analyst forecasts of $3.56. The firm also predicted that its profit in 2000 will be $2.10 to $2.25 a share, down from estimates of $3.91.

In 1998, Raytheon had profit from operations of $1.14 billion, or $3.34 a share, on sales of $19.5 billion.

Revenue for 1999 is expected to be about $20 billion, Raytheon said, or $600 million less than originally expected, because of a shortage of software engineers and delayed orders. Profit margins in Raytheon's defense business will shrink to 12 percent next year, compared with expectations of a 15 percent margin.

Customers such as Egypt and Taiwan have delayed purchases of the Patriot missile. The sale to Taiwan, for example, may not be booked until 2001, the company said on the conference call.

The initial warning of a profit shortfall on Sept. 16 spurred a 12 percent decline in the company's shares, at the time the biggest one-day drop in the stock for at least two decades.

"The fact that the numbers are so far off from the September numbers is amazing--absolutely amazing," Narancich said.