An "unplanned trip" refers to a journey or voyage that was not originally intended or scheduled. It means going somewhere without prior preparation or arrangement. Full definition
No more unplanned trips to the pet store, right at dinner time, when you find out that the food bag is empty! (petnet.io)
If you need to travel frequently throughout the year, with a multi-trip plan you can cover all your planned or unplanned trips while paying much lesser than buying 3 or 4 separate single trip plans. (policybazaar.com)
One of the things i love 2012 was to experience the PNR train, moving out to Malaysia and more unplanned trips. (lamyerda.com)