While I was doing research for my book on Rubik's Cube (published in Budapest in 1980), I was given the opportunity to use the Control Data 3300 mainframe computer of the Computer and Automation Research Institute of Hungary's Academy of Sciences. Here, I met an engineer from Hungary's aviation authority, and soon I had a contract in my hands: I was to simulate the take-off of TU-154 aircraft at Budapest airport. The goal was to tabulate allowable take-off weights given the length of the runway at Budapest airport and varying weather conditions. The requirement was that even in the case of an engine failure (resulting in reduced thrust as well as reduced reverse thrust for braking) the airplane must be able either to take off or come to a full stop safely. Under a follow-up contract, I attempted to simulate the dissipation of carbon monoxide, produced by regular daily aviation traffic, in the volume of air surrounding the airport. I implemented this latter project in Simula-67; as such, this was my first encounter with an object-oriented programming language.