Dancing is like bank robbery, Twyla Tharp famously said — they both take split-second timing. And yet, for dancers, timing is inextricably tied to something completely outside of their control: the orchestra.

It's a big year for the Orchestra of Pennsylvania Ballet. The company is dancing all three Tchaikovsky ballets this season — formidable scores that require not only virtuosic interplay with the dancers, but that also lay down the atmosphere more powerfully from the pit than anything on stage.

The Sleeping Beauty, which opened Thursday night at the Academy of Music, might be the trickiest of the three. Swan Lake is almost painfully gorgeous, and The Nutcracker remains an astonishingly concentrated and inexhaustible gift.

The Sleeping Beauty is not as concentrated, but what it does have is splashes of daring experimentation. Excerpts are a mainstay of the concert hall. But the larger quilt stitched together and led by Pennsylvania Ballet music director Beatrice Jona Affron is, though not concise, an odd and fascinating assemblage of ideas.

Beyond the tunes and waltzes that everyone knows are long stretches that are merely competent and functional; you can hear Tchaikovsky vamping to stretch time until the dancer has finally danced her last dance. This material is monotony itself harmonically and melodically, and seems particularly so coming from a composer celebrated for both.

One layer deeper, Tchaikovsky deploys material that might sound strikingly familiar: the cello solo, played with a loving, masterly touch by Jennie Lorenzo, follows contours similar to a theme in the second movement of Tchaikovsky's Symphony No. 5, and when the fluttering limbs of one ballerina require something gossamer, Tchaikovsky comes up with a near-paraphrase of the "Vivace con spirito" movement of his Manfred Symphony.

It is in the third act, though, the wedding scene, where Tchaikovsky's big imagination really runs loose — portraying cats, jewels, a bluebird, and Red Riding Hood and the Wolf with musical characterizations both sly and sharp.

Ballet conducting is always a compromise of tempos and pacing, and Affron is a deft specialist. Could a waltz have been faster, or an arrival point reached with a more protracted sense of drama? Of course. I have a hunch, though, that were Affron released from dancerly bonds on stage, she might have made some different choices.

The ballet orchestra overall is a good deal sturdier and more polished than it sounded several seasons ago to me in The Nutcracker. A fuller sound should be on any wish list being passed before a donor willing to spring for a larger pit and more players. An orchestral sound that could wrap around the audience would be more than just incidental to the experience; it is critical to how much emotion comes into the house.

The score itself is something of a negotiation between what the dance needs and what makes musical sense. Concertmaster Luigi Mazzocchi had a lovely shape and deep glow in his extended solo, but this was not the Sleeping Beauty solo many violinists like to play.

That concerto-like entr'acte patch of music, through the mysteries of ballet tradition, has dropped from performances of the ballet. Don't worry, it hasn't gone far. Listeners can find it in the middle of The Nutcracker, which is just around the corner once again.