This question gets asked A LOT (def one of the top 5). As the “old” second career guy (I started training at ATP when I was 39) I’m the one who most often fields it. The short answer is no, maybe, yes obviously depending on a) your age and b) your expectations for your career. The main thing you need to understand in all of this is airline pilots MUST retire at 65. Therefore the older you get, the less years you not only have to fly, but to advance. While in other careers you can possibly "climb the corporate ladder) based on your skill, smarts, hard work, social skills, back-stabbing or whatever, EVERYTHING at the airlines is based on SENIORITY. You cannot leapfrog or pass another pilot who is senior to you. NEVER. So let’s try and break this down by age adding a hypothetical 2.5 yrs for training and building time to get to a Regional (keep in mind there are no guarantees and your results may vary SIGNIFICANTLY in either direction):
Under 35: Congrats! You were smart enough to figure out this was what you wanted to do relatively early in life. You’ve got 30+ years you can fly which is plenty of time to climb up to the top of the seniority list. Those closer to 35 will never be Seniority #1 at the airline (ANY plane, any schedule, any days off you desire) but you could definitely be a Capt flying the heavy metal.
35-43: Little bit of a late bloomer but no worries. While you’ll never be #1 on the seniority list (and hold that perfect schedule) you should be able to achieve your goals whatever they may be.
44-48: Ok this is where we have to start managing our expectations. You could potentially make it to a Major but you will never be a 777 Capt flying to Tokyo. You could possibly be a widebody FO or you might even decide to just stay at your Regional. Be #1 on that list, maybe become a check pilot and have a very nice life.
50+: Hopefully you’re the guy (or gal) who maybe flew when you where younger or always had this desire to fly. You don’t need to make the big bucks or fly around the globe, you just want to spend your last years before retirement doing something you love. You probably won’t be going to a Major but that’s cool, those guys are all stuck up anyway!
As I said, none of this is written in stone but it will hopefully give you some food for thought. You see for me I had ZERO expectations when I started training and actually believed all that “you can be an airline pilot” was just marketing. The great thing about that is I’m incredibly thankful and consider myself extremely fortunate because it’s ALL gravy!