‘99% success rate!’
Sounds great, doesn’t it?
You’d probably buy something that has that promise. It sounds really good!
Put into real life though, it’s pretty crap.
A car has around 30,000 parts.
If each part was only 99% good, then you are looking at 900 parts failing out of those 30,000 parts.
Put it another way…
A large airliner, such as an A380 Airbus has around 3 million parts.
That 99% good is terrible as it allows 30,000 parts to fail.
That’s every part of a car failing. Not just a switch, but the spring, washer, fulcrum, each electrical connector, the plastic button itself, the bulb, every part of that switch would fail.
Literally everything on the car failing. Each wheel nut, every tyre, every single component on the stereo, even the cup holder and each section of upholstery… A bit like a British car from the 1970’s.
Would you feel okay flying in an aircraft that boasts it’s parts are 99% fail free? ‘Only 30,000 parts likely to fail!!!’
Even 99.9% fail free still allows for 3,000 parts going wrong in that aircraft. Still not great.
500,000 open heart surgeries are carried out a year. That’s not all heart operations – that’s just full cut open and hands in wet work. 99% success would accept 5000 of those to die.
International air transport saw 3 billion people flying around this year. Just standard passenger flights – not including any other flights.
3,000,000,000 people a year. If 99% of those people survived their flights, that would accept 30 million deaths per year… 99.9% survival would accept just 3 million deaths a year, so that’s okay…?
2014 has been a terrible year in civil aviation. Due to several airliner losses (including shoot downs/missing), 761 lives were lost. Usually this number is much lower. In 2013 it was just 265 lives lost out of around 3,000,000,000 that flew commercially.
That’s more than 99.99999% surviving their flights – and we’re still driving that number
down because even one loss is not acceptable.
That’s why automotive, aviation and medicine etc. work to much, much higher quality standards than a terrible low target of just 99%.