If the hair length does not comply with the company's grooming policy, then probably it will cause problems.
You're probably thinking "I don't know their policy". Exactly. Right now at 17 I doubt you'll be getting many interviews, but once you start training etc, the impression may not be the one you want to convey.
In interviews/first time meeting people, the first 10 seconds are the most important. You haven't even had a chance to speak and you're already being assessed based on your appearance.
Rightly or wrongly, airlines are fairly conservative in how they expect their pilots to look. Hair above the collar, no visible tattoos or piercings.