Hey, I'm an Indian student who has Math AI HL, I had an A in Math in my iGCSEs and my school allowed me take Math AI HL.
Let me tell you that it is not a good idea to shift mid IB from SL to HL as firstly, HL encompasses a huge amount of extra work and content which is covered at a faster pace than SL while being studied simultaneously with the SL course, which is a subset of the HL course. Secondly, it is not prudent as HL papers are much tougher than SL ones in that they have more questions overall which are very twisted in nature. Thirdly, HL paper3 will need a. lot of practice, so covering up in a year's time might pose as challenge; an even bigger one if you have very tough HLs like Physics and Chemistry (which I'm assuming you do since you want to become a pilot).
However, you should aim at taking math AA HL as universities require them if you apply for Science based courses, which I assume you will be applying for since you want to become a pilot. Math AA Hl is. calculus heavy and it helps if you had additional math as a. subject in GCSEs. Anyway, I ask your school for Math AA HL, they might give it to you.