In a scene in David Lynch's Dune, Duke Leto and Paul take an aircraft to observe a spice harvester in action. When a sandworm is en-route to attack the harvester, Duke Leto takes his aircraft down to evacuate the harvester, as the carryall which dropped it off in the first place is nowhere around- what happened to keep the carryall away when the sandworm showed up?
In the source novel, the mystery of the missing carryall was solved later.
“You’ll all be delighted to know,” she said, “that our Duke sends his reassurances. The matter which called him away has been settled. The missing carryall has been found. A Harkonnen agent in the crew overpowered the others and flew the machine to a smugglers’ base, hoping to sell it there. Both man and machine were turned over to our forces.” She nodded to Tuek.