Something I found that I hadn't already posted,,,
Hahneman's hijacked plane landed in Merida Mexico for refuelling, then he demanded the plane fly over British Honduras (Belize) but he jumped in neighbouring Honduras. The 727 did a loop and landed back in Merida Mexico..
Of course Cooper's initial demand was the same, to fly to Mexico for refuelling.. that was re-negotiated due to configuration range..
So, Cooper's plan A may have been to jump at the end of the flight in Mexico/Central America, but his plan B became to jump where he did.
"The replacement craft--also a 727--was backed tail to tail with the hijacked plane. The hijacker, carrying his gun and encircled by stewardesses and other crew members to shield him from possible sharpshooting FBI agents, transferred his gear, including six parachutes he had demanded and received, from the one plane to the other. From New Orleans the plane flew south landing at Merida, Mexico, a city on the coast of the Gulf of Mexico. After refueling it continued south over Central America. After the hijacker jumped, the aircraft returned to Merida where the crew rested for several hours before flying to Miami."