The escape was most likely during the outgoing tide — not flood tide — because studies of the June 11, 1962 conditions found the current then was strong enough to carry a raft west or toward the Golden Gate, depending on the exact launch time.

Quick scoop

If they left around 10 p.m., the outgoing tide would have been especially strong and likely pushed them out toward the bridge and the open ocean.

Other reconstructions suggest the narrow survival window was closer to 11:30 p.m. to midnight, when timing and slack water could have helped them land near Horseshoe Bay.

What that means

  • Ebb tide = water flowing out to sea.
  • Flood tide = water flowing back into the bay.
  • The evidence points to ebb/outgoing tide being the relevant tide at the escape time.

Bottom line

So, for the Alcatraz escape, the best-supported answer is ebb tide rather than flood tide.