Des Moines International Airport is supporting an increase in passenger fees that would help plug a $200 million gap in financing for a new terminal and related construction at the Des Moines facility. Congress is considering the first increase in the so-called passenger facility charge since 2000. Passengers are required to pay the fee, now limited to $4.50 per trip, to help finance new runways, terminals and other construction. That $4.50 is worth approximately $2.38 today. Airports are asking for an increase to $8.50. The $4 increase in the fee would mean an extra $4.6 million a year for the Des Moines airport, based on last year’s enplanement data. or $92 million over 20 years, said Kevin Foley, airport executive director and general manager. “We should be able to bond against that,” he added, meaning the new fee would have an even bigger impact on airport finances, closing much of the cash gap for the new terminal.