You will need 1,500 Hours in order to get this pilot license. In most cases people will flight instruct in order to get this amount of time but you can build the time from a commercial pilot certificate in order to get this time.
In most cases if you get a job that requires the Airline Transport Pilot License, the company will pay for it during your training. The air carriers are required to perform flight tests every six months so this usually comes as part of your recurrent training.
Airline Transport Pilot License
Private Pilot License Information
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