When our kids were little, every single time my husband announced, "I'm going for a run", our son would ask, "Daddy come back?" We thought this was hilarious; mostly because life was really hectic at the time, and while the thought of not returning when we left the house had never occurred to us, it did contain a certain level of appeal on some days.
Interestingly, I don't remember either child being upset when we left the house or left them somewhere. They just wanted to understand when we'd be back. Maybe we were lucky. Or maybe they reflected our attitudes that outings like daycare, school, and trips were fun. It was probably a combination of luck and attitudes. And while I wish we could take full credit for the ease with which they handled transitions, I realize in hindsight that both kids seemed innately eager to "get out there" and experience the activities we described to them and they read about in books.
Some working parents describe sad scenes when it comes to business travel and daycare. They tell stories that include tears and angst. It has me wondering if the kids might be reflecting their parents' feelings. It's possible that my own kids may have looked forward to having one of us leave on a business trip since it usually meant a change in routine that could be fun; like pancakes for dinner or a little less attention (and more freedom) as the "single parent" left behind struggled to "survive".
Either way, it may be worth asking yourself if your child's tears and fears stem from your own behavior. I don't remember my own dad traveling for work very often, but when he did, it was exciting for all of us. Not only did he return with stories of faraway places, but he brought gifts; tiny bars of soup and teeny weeny bottles of shampoo. At some point in my childhood I vowed to go to college so that I could get a job that allowed me to travel and collect these prizes for myself. I learned early on that business travel is exciting, and if I worked hard, I'd be able to experience it for myself one day.