At least 3 planes.
1 One plane for ransom (Did this plane stop somewhere before Iran and another finished route?).
2 One from Iran -Geneva with prisoners
3 One US plane in Geneva -US with prisoners
Did (2) bring back kickback $ or was that diverted before hand?
https://www.politico.com/story/2017/04/24/obama-iran-nuclear-deal-prisoner-release-236966