It takes as little as 18 months but more often 2-3 years.
Yes, you need a degree for the majors but the regionals only require a 2 year (some none at all). An aviation degree is NOT required. Any major will do.
The usual route to the airlines is flight training for the Private license, Instrument rating, Commercial license and multi-engine rating in about 12-18 months. Quite often a person will also get their Flight Instructor certificate and teach as a way to build flight time. The regional airlines hire people with 1,000 hours of flight time. (You don't need 1,500 hours and the Airline Transport Pilot certificate to get hired, although it makes you a better candidate.) Once a new commercial pilot with 250 hours has instructed or built up time via other small jobs, which takes another 12-18 months, they can apply at 1,000 hours and be hired by a regional airline. For about 85-90% of the industry, this is the usual route. It costs about $40,000-50,000.
There are also some "academy" style programs that will train you for the PPL, Instrument, Commercial, & ME in 12-18 months, plus some airline style ground school, then offer a pilot an interview with an affiliated regional at substantially reduced flight times. This method of training often costs $60,0000-$80,000 and doesn't guarantee a job- only an interview. If the candidate passes it successfully, they will get an airline job at around 300-400 hours of flightime in aboout 12-18 months.
The U.S. majors require several thousand hours experience. After building that time at a regional, one can then more on to a major.
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Here's a straight answer. A commercial pilot is one who flies for hire (gets paid to fly). That includes anything from crop dusters to private jet pilot. A commercial pilot is not to be confused with and Airline Transport Pilot (ATP) who flies the big planes like Boeing and Airbus. There are a few routes to being a commercial pilot. Student Pilot, Private Pilot, Instrument Rating, Multi-Engine then/or, Flight Instructor, Commercial Pilot. Flying about 6 - 8 hours per week, it will take you about a year and a half to complete.
couple of years
you have to have minimum 260 lessons to become proper pilot
It takes months. First you have to go through training, which takes months. Then you have to get lots of flight time, which takes more months. It just depends on how fast you can rack up 1500 hours of flight time. You'll have to go to a school and get your commercial pilot's license long before you bother applying for the job of airline pilot. After you're hired, you'll get even more training.