A 'tech' stop is usually associated with a requirement to refuel the aircraft due to the destination being too far away to do it in one go. Flights on the B757 to the Caribbean from the UK (many years ago) used to tech stop at Bangor, Maine (and vice versa). We were allowed off the aircraft to stretch our legs and no customs were involved as far as I remember. Do you know what aircraft type you are going on because if it's a 747 then that will blow this little theory rightout of the water