U.S. stock index futures slipped on Tuesday, a day after Alcoa reported in-line quarterly profit but lower-than-expected revenues as the Dow closed above 11,000 for the first time in almost 19 months.

Alcoa Inc, a Dow component, said results benefited from higher prices and that its markets were improving, but warned it could face strikes at its U.S. operations. Shares of the aluminum producer fell 1.6 percent to $14.34 in premarket trade.

After the closing bell, strong earnings are expected from Intel Corp, possibly offering further evidence of a recovery in demand for electronics and personal computers. But a stronger dollar and elevated expectations could dull any effect on technology stocks.

We kicked off earnings season with Alcoa, which disappointed and is certainly not going to be the poster child for first-quarter earnings season, said Arthur Hogan, chief market analyst, Jefferies & Co in Boston. The problem with Alcoa is they don't control their input costs. Intel clearly controls their input costs and certainly controls the supply and demand chain. It's more appropriate to wait until tonight, and look at Intel to set the tone rather than Alcoa.

S&P 500 futures dipped 2.2 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures lost 21 points, and Nasdaq 100 futures fell 6 points.

CSX Corp, the No. 3 U.S. railroad, is expected to report stronger earnings as the economy, and particularly the auto and coal industries, gain momentum.

At 8:30 a.m. EDT, the Commerce Department will release February international trade figures. Economists in a Reuters survey forecast a $38.5 billion deficit compared with a $37.29 billion deficit in January.

Also at 8:30 a.m., the Labor Department releases import-export prices for March. Economists forecast an 0.9 percent rise in imports and a 0.3 percent increase in exports. In February, import prices fell 0.3 percent, and exports were down 0.5 percent.

Oil futures dropped for a fifth straight session to below $84 a barrel, almost erasing April gains, as a forecast increase in U.S. crude inventories fanned concerns about excess supplies and sluggish demand growth.

European shares inched lower Tuesday ahead of key U.S. earnings reports, with banking stocks under pressure and commodities lower as crude and gold prices slipped.

U.S. stocks rose on Monday as expectations of solid first-quarter earnings spurred buying in the financial, energy and industrial sectors.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)