I assume that LCC stands for "low-cost carrier'? I only figured that out because of the context about airlines. Please don't use abbreviations/acronyms when you ask questions. If we can't understand the question, we can't help you. I think what you want to say is "It was my first flight on a low cost carrier and I found it surprisingly comfortable".

Grammatically not wrong, but I don't know what you mean without the context. "Super" sounds very casual so I guess you are talking to your friend about your flight experience? What is LCC? I guess it is a airplane- company like JAL? If I would assume what you are trying to say, LCC is my first one I have ever experienced my flight with, but it is super comfortable!

It's an airline? So, why "but"?

〇〇○ is my first LCC flight but it is super comfortable...? 〇〇○→name of LCC ( flybe, Ryanair)

No clue what you mean to say.