Not flying, but....
A driver on a Ramadan fast had not eaten for 16 hours before his train was derailed, a report has found.
The crash, near Paddington Station, affected services for days.
A Rail Accident Investigation Branch (RAIB) report said it was "unable to determine" whether fasting and interruption to sleep was a factor in the crash.
But the investigation recognised there was research showing fasting can affect people's concentration levels.
The train, which was not carrying any passengers, was automatically derailed after passing a red signal at about 18:30 BST on 16 June.
Fasting and driving
The Rail Safety and Standards Board (RSSB) has published research on the effects of fasting on fitness to drive.
It says fasting can have a range of effects including tiredness, dizziness, dehydration, headache, and a reduction in concentration, prompting safety concerns.