I'm 2m10, and have over 90% success in getting better seats because of my length on longhaul flights. (Only two failures, and in one of those cases I got an empty row instead. In the other one, I might not have pushed enough.)
I understand that it is much more common when you are amongst the 0.01% tallest than amongst the 1% tallest. (the irony...)
Here is what I do:
- Never ask for an upgrade (greedy), but for a seat with more legroom (understandable).
- Ask it at every step of the boarding process, but give the other side the chance to offer it to you first. They work in a service industry, and generally love to offer service. And my length isn't a secret.
- If you have checked in online, go to the counter and ask for the better seat. You might hear that you can purchase something. That's good. This means there is availability. I've always refused politely. And I don't want to encourage such practices too much. Although I understand the position of the carriers too.
- Ask at the gate. They can rarely change your seat, but they can inform the cabin crew. (To make sure that that single exit row seat is given to someone of 198cm who considers himself tall
).
- Ask in the plane, but wait for the offer. Standing in the door opening when even the shoulders aren't visible usually triggers it.
- If this really doesn't work, you can wait until the person in front of you tries to recline so that both of you can explain that the seating is not optimal.
- It's my opinion that showing willingness to take the bad seat creates a lot of goodwill.
- Same for dressing well and being polite.
(Two failures were Qantas and Tam, btw.)
Edit: If you get a better seat with more legroom, thank the crew afterwards. There isn't such a great chance that you'll encouter them later, but there is a big chance that they will encounter other tall people later...