All the pre-war KLM aircraft were named after birds and the last letter of the registration was to be the same as the first letter of the species.
Jhieminga,
Thanks, I didn't know that. I had wondered why they had chosen an Indonesian bird's name. I have done quite a bit of research into the PH-ALU Uiver (Stork) crash at Rutbah Wells, but I never made the connection between the registration and the name!