Q. What is the maximum age for a child to travel on your lap during a flight?

A. It depends on the size of your lap. Just kidding. Lap children should be two years of age or younger, although as I’ve said in this column before, I don’t recommend carrying a child in your lap in a car going 100 miles per hour and nor do I recommend doing so on a plane landing at 100 miles per hour. Keep in mind that although lap children ride free on domestic flights, you’ll pay 10 percent of the applicable adult fare on international ones. Even if you’re flying on a free frequent flyer ticket internationally, if the equivalent business class fare is $5000 round-trip you’ll pay $500 for your lap child. It also makes for a very uncomfortable flight.