After two recent air travel incidents, many people will be worrying just how safe it is to travel by aircraft.

The first occurred on the 5^th of January, a door blew out on an Alaska Airlines flight from Portland, Oregon to Ontario, California, as reported by the BBC. The blow-out occurred at 16,000 ft (4,876m, causing oxygen masks to be deployed and the jet to make an emergency descent , after which it returned to Portland.

Aircraft cabins are pressurised to the equivalent of 10,000 ft, so the sudden depressurisation would certainly have been noticed by the passengers. Most people, however, can tolerate air pressure at 20,000 (I have done so, while working, including moving heavy equipment). One commentator wrote that many passengers would probably have died if the blow-out had occurred at 30,000 ft (normal operating altitude for jets), although I suspect that passing out would be a much more likely outcome.

The Boeing 737 Max has had many problems, with hundreds of deaths in two high profile crashes and the whole fleet being grounded for over a year while changes were designed and tested, and the 737 Max was re-certified. Boeing must be grateful that this latest problem doesn't appear to be their fault.

More recently a passenger noticed, while looking out of the window just prior to take-off from Manchester (England) airport, that 4 bolts were missing from a wing panel, as reported the Mirror. The Airbus A330 wing-panel has a total of 119 fasteners, so the missing bolts were unlikely to have caused a crash. Such panels are often removed for inspections as part of routine maintenance, so this is not a case of the bolts having been forgotten at the factory.

Many readers will have read that air travel is the safest form of travel. This, however, is calculated either per mile travelled, or per hour travelled, and, for me at least, air journeys are much longer (in both time and distance travelled). What I would like to see is statistics calculated per trip, so that we can all make an properly informed decision.

This is a common problem with official statistics, which often tell us what someone else wants us to hear rather than what we need or want to hear. Such statistics should more properly be designated propaganda. As they say, "never trust statistics that you didn't falsify yourself."