The Havoc transport is an unreleased vehicle in Tribes: Ascend. It is a remake of a Tribes 2 vehicle of the same name. The Havoc is designed as an air transport which allows heavy classes to be quickley moved across the map. In previous Tribes games it was common to see full Havoc's circling above the enemy base launching all sorts of weaponry.
The Havoc is known to be included in the Tribes: Ascend game files. One of the promo trailers for the game shows it flying past the camera near the end. In addition, several players who have hacked the game files have posted youTube videos of this vehicle. One video simply shows the player spawning Havocs at the Vehicle Pad while a more recent video shows the player actually flying the vehicle and demonstrating a carpet-bombing weapon (a new addition since Tribes 2). This video also shows the player rotating through 4 passenger seats besides the pilot. At this time there does not appear to be a tailgunner position as there was in Tribes 2.
Official Trailer showing the Havoc flying with a Shrike
Spawning Havocs in a game by HiRezBartTribes (Not a HiRez employee, but a well know player who has hacked the game files to show HiRez their programming vulnerabilities).
Havoc Piloting and demostrating it's new weapons (most recent video, Aug. 25th, 2012)