Hi Jonah
I too like an aisle seat as I get cramps in my legs following cancer treatment and have to be mobile but there have been occasions, despite arriving at the airport nearly 3-4 hours ahead, when I did not get an aisle seat. BA was the worst airline when I went to South Africa - apparently passengers had to pay to guarantee an aisle seat - a lady sitting next to me told me both her and her husband had to pay! Years ago window seats were popular and it seems aisle seats are popular nowadays. South African airways were very good and despite not having any aisle seats available when I checked in, they did find me one at the boarding gate. When I don't get an aisle seat, especially on a long haul flight, I just warn whoever is sitting in the aisle seat that I will have to get up often! Good luck in getting an aisle seat and enjoy Kerala.
Regards
Jaya