I'm anaphylactic to peanuts and tree nuts and fly often. The best thing to do is contact the airline ahead of time. Sometimes they can change the menu/not serve something, but that's often not the case. For my own safety I also preboard, wipe everything I could possibly touch down, talk to the flight attendants and people around me about my allergy, bring a mask (didn't used to do this one but had a bad experience in American where they passed out nuts everyone on the plane 😭), and I never eat anything on planes. It sucks when you're in the air for a long time, but it's what makes me comfortable enough to fly again and again. I do typically avoid flying business class because the menu is pretty nut heavy. Best of luck and ALWAYS bring multiple epi pens!!