One of the biggest challenges was writing software to integrate ADS-B with an older, less sophisticated collision-avoidance system.

FORBES: Technology

Mr MacCulloch copes better with the challenges of writing about modern Christianity, relegated to the margins of social, political and scientific developments.

ECONOMIST: A history of Christianity

Some of the biggest challenges involved in writing and teaching about contemporary China are linguistic and terminological.

FORBES: Terminology For A Fast-Changing China