Eastman Kodak reported higher earnings for 1979, but higher costs -- especially the spiraling cost of silver -- cut fourth-quarter earnings 11 percent despite a 12 percent sales gain.

The camera and film giant said yesterday that 1979 net income was $1 billion ($6.20 a share) on sales of $8.03 billion compared with net income of $902.3 million ($5.59) on sales of $7.01 billion the previous year.

However, fourth-quarter net income was $294.7 million ($1.82) on sales of $2.59 billion against net income of $331.4 million ($2.05) on sales of $2.31 billion in the 1978 fourth quarter.

Kodak's U.S. and Canadian photographic division had an 11 percent increase in sales to $4.47 billion, international photographic division sales jumped 21 percent to $2.87 billion and the Eastman Chemicals division had sales of $1.78 billion, up 16 percent from the previous year.

American Airlines said yesterday that it's earnings dropped 35 percent last year to $87.4 million from $134.4 million in 1978, the result in part of the grounding of the DC10 fleet during the airline's peak travel season.

Earnings per share dropped to $2.63 from $4.27 a share the previous year.

Revenues were $3.253 billion last year, an increase of 18.9 percent from $2.736 billion in 1978

American said it lost $3.8 million in the fourth quarter last year compared with net earnings of $7.3 million (15 cents a share) in the comparable 1978 peiod.

Albert B. Casey, chairman and president, said a $286.8 million increase in fuel costs and severe and widespread weather conditions in the first quarter also contributed to the decline.

Fuel expense for the year totaled $801.5 million, up 55.7 percent from 1978, while consumption rose just 5 percent.

B.F. Goodrich Co. said yesterday that revenue from its tire business dropped 70 percent in the fourth quarter last year, largely the result of slumping auto sales that caused earnings to fall 27 percent from the same three-month period in 1978.

Goodrich, the nation's third largest tire maker, said earnings increased 17 percent last year to a record $82.6 million ($4.89 a share) from $70.1 million ($4.39) in 1978. Sales totaled a record $3 billion, up from $2.6 billion the previous year.

The company said it earned $14.8 million (87 cents) in the final quarter of 1979, down from $20.3 million ($1.20) in the same 1978 period. Sales totaled $775.3 million, up from $682 million the previous year.

Goodrich said sales of chemical products surpassed the $1 billion mark for the first time, with operating income from chemicals up 101 percent to $108.4 million from $53.8 million in 1978. Goodrich said strong demand for polyvinyl chloride allowed price increases to offset rising costs.

Salees of tires and related products were almost unchanged in the three months ended last Dec. 31 and the year. Tire sales in 1979 were $1.3 billion.

Signal Companies Inc. said it earned a record $203.7 million ($5.28 a share) last year, up 26.8 percent from $160.7 million ($4.17) in 1978.

Forrest Shumway, chariman of the multi-industry company, said sales totaled $4.24 billion last year, up 19 percent from $3.57 million in 1978.

Fourth-quarter net income was $45.1 million ($1.17), up 19 percent from $37.8 million (98 cents) in the last quarter of 1978. Fourth-quarter sales were $1.09 billion, up 19 percent from $915.7 million the previous year.

Shumway said Signal's high-technology units -- Garrett Corp., a manufacturer of aircraft turboprop engines and turbochargers for trucks, tractors and mass transit equipment, and UOP Inc., involved in energy, environment and engineering -- turned in record performances that offset a slight decline in revenues from the truck manufacturing operations of Mack Trucks Inc.