I fly mutiple times a week nearly every week for work. It has happened a few times that I had to travel on a minor fast day and I was at times surprised to see visibly religious people eating and drinking on planes and in airport lounges.
Let’s assume these people were traveling for the sake of earning a living or for other permitted reasons, and that they were normally healthy.
Are there particular lifting of fasting restrictions if traveling for a permitted purpose? Are there poskim who would allow eating/drinking lechathila? Does it make a difference if the fast happens on the day after the “real” date because of shabbat?