Sony Pictures' RV camped out in the top spot at the boxoffice for the weekend as the Robin Williams starrer hooked up an estimated $16.4 million from 3,639 sites in its debut. The Barry Sonnenfeld-directed family comedy, which carries a PG rating, marked the fifth No. 1 opening for the distributor this year, says The Hollywood Reporter.

Universal Pictures' much-talked-about United 93, the story of the one hijacked plane on Sept. 11 that didn't reach its intended target, debuted in the second spot with an estimated $11.6 million from 1,795 theaters. The R-rated drama from director Paul Greengrass had the highest per-theater average of the top 12 films and also generated the highest theater grosses in North America on Friday and Saturday at the AMC Empire in New York. Buena Vista Pictures' Stick It had a surprisingly strong bow with an estimated $11.3 million from 2,038 houses, enough to catapult the film into the third spot. Early tracking had the PG-13 drama, centering on the world of competitive female gymnastics, pulling up a single-digit gross. Jeff Bridges and Missy Peregrym star in the Spyglass Entertainment co-production, from writer-director Jessica Bendinger. Not surprisingly, the largest portion of the audience was female and under age 18.

On the cusp of the summer blockbuster season, the international boxoffice was largely static during the weekend as 20th Century Fox International's Ice Age: The Meltdown remained No. 1, garnering $25.3 million from 8,396 screens in 61 territories. The film's weekend estimate was just $2.3 million higher than the previous weekend despite coming from more than double the number of overseas markets. Meltdown's international gross shot past the $350 million mark, logging in at an estimated $373.6 million. The film's five-week reign as the top overseas grosser is undoubtedly finished since the first of the big studio tentpoles, UIP/Paramount's Tom Cruise vehicle Mission: Impossible III, arrives internationally this weekend, followed by Sony's The Da Vinci Code on May 19 and Fox's X-Men: The Last Stand on May 26. Universal's United 93, which opened domestically this frame in the No. 2 spot, begins overseas dates June 2 after screening May 26 at the Festival de Cannes.