You'll need to define what you think constitutes a long haul pilot.

"Long Haul," typically long international legs, are flown by cargo and passenger airlines, and there's some corporate and charter work doing that too (a lot of cargo charter). In the United States, it may take quite some time to get the seniority with a major airline to be flying long international routes. The cargo airlines are often all long haul, and consequently it's what you do from day one. Getting there, getting the job, however, requires a long time, because you'll need enough experience to not only apply for the job, but to compete with others who are applying for the job.

Long-haul flying has advantages and disadvantages. There's usually a lot less commuting to work, but once at work, it can be a long time before you get home.

There's really no chance of going from a regional airline to a major airline and jumping into long haul work, but there are opportunities in all cargo airlines to come from a regional right into a 767, 747, MD11, or other wide body aircraft doing international long routes.

There is no school for long haul; you'll be given the specific training for the aircraft and the job by the company that hires you, and that company will hire you based on your background, experience, qualifications, etc. You'll need flight hours, the ATP pilot certificate, good instrument skills, and enough work history to make you competitive. If you're seeking a major airline, you'll need a four year college degree (at a minimum). For all-cargo airlines, degrees are sometimes preferred, but not necessary.

Once you gain experience and want to apply to an operator that does "long haul," you'll need to meet two sets of minimum experience: the company hiring minimums, and the competitive minimums. The hiring minimums are values of flight time and qualification that the company considers the bare minimum for an applicant (eg, 2,500 hours total flight time, for example). The competitive minimums are different; nobody tells you what they are, but it's the numbers you'll need to compete against others who are are applying for the job. The published minimum might be 2,500 hours, but if every other applicant has 15,000 hours, then that may be the competitive minimum.

I've flown "long haul" with pilots who ranged from furloughed major airline pilots to ag pilots to regional, charter, corporate, fractional, military, and other pilots from all kinds of backgrounds. Some are doing it for the first time, others have done it their entire career.

What attracts you to the idea of "long haul" flying?