While he might not be able to fly, Bucky would be able to get there as back up. He's armed up (thanks, Featherstones weapon storage) and is a crackshot with a sniper rifle. So he'd be feet on the ground offering up support. Mostly to try and distract Olexa where possible. He'd also be able to get up the side of the building if needed. But that'd be more a case of...punching footholes into the side. So probably not the most suitable method on a falling building. But hey, if things go wrong, at least he heals fast?