The Backup

John Healey is the United Kingdom's Secretary of State for Defence. On Friday, the Royal Air Force plane carrying him home from a trip to Estonia was subjected to GPS jamming for approximately three hours near the Russian border.

The pilots switched to backup navigation.

The backup navigation is the navigation system the Royal Air Force uses when the GPS navigation does not work. They prepared this before the flight. They prepared it knowing GPS jamming near Russia was possible. The backup worked. John Healey landed safely in London.

The UK Ministry of Defence described the jamming as "concerning."

Concerning is the word you use when something you prepared for happened anyway. Someone, at some point before Friday, calculated that the GPS might not work near Russia. They built the backup from that calculation. On Friday, the calculation proved correct, the backup worked as built, and the Ministry of Defence announced it was concerned.

The concerning part is not that they needed the backup. The concerning part is that they had to build one.

Russia has not described it as a problem they are monitoring.