Last year, traveler complaints jumped 34 percent to the highest level since 2000.

One particular growing complaint comes from parents who are finding it increasingly difficult to sit next to their children.

With more and more airlines selling preferred or premium coach seats, parents can neither find a seat nor afford to pay the extra costs.

Inevitably, it gets ugly once the plane is boarded, as parents are often begging other passengers to switch with them.

When I was a child, my parents lectured me about good behavior on airplanes.

Today, many parents are doing the opposite with their kids.

After all, the more obnoxious or loud the child seems to be, the more quickly passengers are willing to switch seats.

On airlines like Southwest, which offer early boarding for about $15, some parents have figured out how to game the system.

One parent pays the premium, gets on the plane, and then hogs the other seats.

This is simply a warning about this unexpected consequence of charging for coach seats.

For more information about airlines and added fees, check out:

• The Problem With Ticket Change Fees
• Why Cheaper Jet Fuel Doesn’t Mean Cheaper Airfare
• Are Premium Economy Seats Worth the Price?

Keep reading for more travel tips.