So sorry to hear about your dad hun

If your more comfortable using a pull up then do that hun and like Lulu said you can always take him to the toilet regularly too. Our last flight with DS we kept him in jocks and made sure we took him regularly. It was only a 6hr flight so obviously much shorter than your flight. On our flight home DS said he had to go NOW and there was a bit of a queue for the toilet so DH just asked the few people waiting if we could go first. I think you'll find most people are pretty accomodating when it comes to newly toilet trained toddlers so you could always do that if absolutely necessary!