The Federal Aviation Administration proposes more flying time and tougher rules for pilots of commercial airlines.
Under the proposal co-pilots would have to fly 1500 hours in order to receive an Airline Transport Pilot Certificate.
Currently only 250 hours are required.
The FAA's proposal would also require additional training and testing for first-officers.
The rules stem from the 2009 crash of a Colgan Air Jet near Buffalo, New York that killed 50 people.
The NTSB blamed the pilots for failure to manage the flight, deal with icing and maintain air speed.