(AP) — The airlines serving small markets in Nebraska and Iowa have had a hard time finding enough pilots since new rules took effect last year, so numerous flights have been cancelled.

The cancelled flights create hassles for passengers, and they could make it harder for small airports to qualify for federal subsidies. Airports must serve at least 10,000 passengers a year to qualify for the subsidies.

U.S. Senator Mike Johanns says he thinks the Senate Commerce Committee should hold a hearing on these unintended consequences of the new pilot-qualification rules.

The new rules that took effect in August require co-pilots to log 1,500 flight hours and pass the Air Transport Pilot exam before they can work for commercial airlines. Previously, co-pilots were only required to have 250 hours experience.