He's obviously going to grab the nose of the plane and scoop them all up like it's a big ol' game of jacks.

How about he lands ahead of them then uses his repulsors to juggle them all until he catches and gently lets down each one of them, one at a time? Because as it turns out, Iron Man is also a master juggler.

It's simple math. If you divide 4 by 13 (and I'm pretty sure Iron Man has a built-in calculator) you get 0.30769. This means that Iron Man can carry 30.769% of the mass of bodies that's falling. He should be able to collect the head, neck, and collarbone of each person (using some laser thingy for this purpose) and rush them to Reed Richards's laboratory at Four Freedoms Plaza in Manhattan where they could be attached to android bodies which Richards undoubtedly keeps handy for just such an eventuality. Easy-peasy.

Barring that, he could just save the hot babes.

Simple, just use the Bat-Emergency-Parachutes from his utility belt.