Happened twice to me so far (only 19 so plenty more opportunity yet...
)
First one
Travelling back from Los Angeles to Newcastle with the family, booked via Atlanta with Delta to Gatwick, and then completely separate BA to Newcastle.
To cut a long story short we were diverted to Augusta due to weather and then eventually arrived into Atlanta around 2 hours late, meaning we missed planned Gatwick flight. No bother, Delta had automatically rebooked us on the one 2 hours later, also leaving 45 mins late due to delays etc. Arrived at Gatwick around 2:30 later than originally planned, leaving us 30 mins to make connection to BA including reclaiming baggage etc. Anyway we strolled through the terminal thinking we had no chance, arriving at BA check in about 20 mins before departure, check-in staff radioed dispatch who very kindly accepted us and our bags, and after a sprint through the North Terminal we were onto the aircraft and cabin crew got us some drinks seeing us very hot and bothered. Arrived at Newcastle to find only 1 bag (out of 8) had gone missing (as it had to be separately handled at LGW), well done BA! Reunited with final wheely box the next night, delivered to our home.
Second one was more annoying.
Going to Belfast for the day with some mates from university, one of those silly 2p Ryanair flights, 1p each way. Anyway friends car broke down, so another mate drove up from Clowne to Sheffield and then all the way back to East Midlands, accident on M1 meant we arrived with 30 mins before departure, long queue for security = no chance. Had a day out in Skegness instead, not quite the same but fun nonetheless.