A rare configuration Atlas V 431 launched from Cape Canaveral Air Force Station on December 18, 2016, carrying EchoStar 19, a high speed internet satellite from HughesNet. The flight was a success and United Launch Alliance earned their check. This Atlas had three solid rocket boosters, supplying asymmetric thrust for the first portion of the boost. Thus, the RD-180 engine nozzles were programmed to gimbal or vector the thrust slightly to the side to keep the rocket on its proper course.
On this clear day, I was able to capture the water vapor mach cone that formed around the rocket as it passed through maximum dynamic pressure. Also visible was the sight of the boosters being jettisoned from the vehicle. It was the third time this 431 configuration has ever flown, proving to be an excellent show.