For those who may not be familiar with FAA regulations, there are many routes to being a professional pilot other than being an airline transport pilot (ATP) flying Federal Aviation Regulations (FAR) Part 121. As with all things FAR, it’s complicated, so a detailed treatment from the very first comment would quickly become boring and overwhelming.

Reaching ATP minimum required 1,500 flight hours has multiple routes to it. Unfortunately for people who work their way up through the ratings as civilians, they are competing against retired military pilots who did not go into debt for their training and who are receiving pension payments. (Military aviators certainly paid for their training in a different way, and I am making no comparison of their respective costs.) Retired military pilots are frequently hired directly to major airlines whereas Billy and Susie Civilian start off at regional airlines.

Even with ATP certificate in hand, it’s not yet fat city. Airline pilots have to work their way up through the seniority ranks, beginning with crummy ready reserve where they sit around hoping for a ride. Other flavors are short call and long call, the difference being how quickly the pilot must report for duty after receiving the call. Moving up to more desirable bases and aircraft goes through a complicated bid process[0].

[0]: https://www.reddit.com/r/flying/comments/8eaupt/moronic_mond...

Yes, compensation relative to the training expense used to be horrible for first officers and even captains at regional airlines, starting in the $20k range annual compensation. Again recall that military retirees have their mailbox money coming in. Because of the pilot shortage, first officers at regionals now start around $60k annually.

Two common civilian paths to ATP minimums are becoming a certificated flight instructor (CFI) or flying aerial survey, photography, air tours, private carriage, diver driver (i.e., flying skydivers) and so on. In reality, there may be some blend because all of the aforementioned tasks require a commercial pilot certificate. Because the airlines are a training environment, there is at least some degree of preference for CFIs rather than someone who schlepped around for a thousand hours towing a banner over the beach in a 152. These are not minimum-wage jobs. Someone with a wet commercial ticket might make twenty bucks an hour. Here again, the would-be ATP is competing against fellow time builders trying to get to 1,500 hours. More advanced instructors (e.g., CFI-Instrument, commercial instruction, or complex instruction) command a higher hourly rate, and instructors get paid for both flight time and for ground instruction. It’s not great money, but they aren’t starving either: starting in the $30k range up to the $50s — a lot like apprentices in the skilled trades.

Candidates for the commercial pilot checkride must have at least 250 flight hours. The commercial airplane ticket comes in four flavors along two axes: single- or multi-engine and land or sea. The least expensive is airplane single-engine land (ASEL). To reach that point, trainers in this class rent between $100 and $200 per flight hour “wet,” inclusive of fuel. Include instruction, test fees, gear, and the cost of an instrument rating (which I am glossing over) will total to around $30k. Some flight schools and operators of multi-engine aircraft will foot the bill for the multi rating and MEI in exchange for some number of flight hours on the back end with a clawback if the pilot leaves for another opportunity.