The Alvin Ailey American Dance Theater began a week's engagement at the Kennedy Center Opera House Tuesday night with a program that gathered momentum very gradually as it went along, working up to full steam only at the end. The company followed the same curve of ascent.

As the start, the dancers were not exactly what you'd call sluggish - that's not a word ever likely to apply to this mostn highly energized of troupes - but they did seem to lack that extra measure of impetus that makes the difference between electric and merely brisk performance.

By the evening's close, however, the familiar Ailey blaze was roaring once again.

The evening's peak came with the final dance, George Faison's "Suite Otis," one of a number of local premieres the Ailey troupe will present during the run. It's a tribute to Otis Redding, and set to half a dozen of his finty song recordings."

Faison uses the jazz dance vocabulary with wonderful surety and flair in this piece. The finale, for instance, is a kind of choreographic "visualization" of the bluesy "Try a Little Tenderness," the dancer's bodies responding to every bend of the melody with analogous flexings of their own.

The songs are quite varied in character, and the dances too. A couple of them pit sassy females against strutting males in several gamemanship, with tight ensemble formations cutting the stage space at razor-sharp angles. One is a comic duet for spatting lovers, who are cheek-to-cheek one second and flailing away at each other the next.

Perhaps the best is the "I've Been Loving You Too Long," a chain of increasingly rapturous duets with a knockout finish,

A work by Lar Lubovitch had to be postponed because Sara Yarborough was unable to make the tour. In its place local premiere, Alley's won "Pas de Duke," and Mikhail Barysgnikox and danced here Tuesday night by Jameison and Mel Tomlinson.

It's a spiffy virtuoso number that shows off Jamieson's wondrous coil and spring to fine advantage. Clive Thompson, Mari Kajiwara, Donna Wood and Enid Britten were outstanding in Ailry's "Hidden Rites" and "Choral Dances," despites the lackluster choreography of both works.