Sunday, March 29, 2015

Is it safe to fly?

The tower at Jeju Airport, South Korea.

The question following any plane crash, especially in the so called industrialized or western world where flying "should be safe", does however usually come out as quite the opposite.

Whether it is asked to gray haired colleagues over lunch, to your sofa hugging husband while watching the 7 o'clock news or entered in the search box of Google. Whether it is asked in fear or anxiety or just out of innocent curiosity.

- Is it dangerous to fly?

There is no doubt about the answer. Or, at least, there shouldn't be. 

No, it isn't. 

- But how could that Germanwings plane crash like that? Over France, even? And Air Asia? And Malaysian Airlines?

There is always a follow-up question.

And it can only be answered properly by looking at the numbers, doing the maths. 2014 was the first year in aviation history that saw over 100,000 commercial flights every day. Or 37.4 million flights altogether. I have gone through Wikipedia's list of fatal air crashes involving commercial aircraft and counted fatalities since 1990. I have left out cargo flights and people killed on the ground, including people killed in hijacked aircraft by security forces on the ground.  

1985 deadliest yet
The deadliest year in aviation occured almost 30 years ago. A staggering 1,987 people died back in 1985. That is 370 more than in 1996, the worst of the last 20 years. 2013 was on the other hand an extremely safe year, with "only" 186 deaths through 8 fatal accidents. The tally increased manifold the next year, in large parts due to Malaysian Airlines' annus horribilis. 920 people died in 7 commercial passenger flights, one less accident than in "the best year ever". 2014 did in other words see among the lowest number of fatal accidents in a year, but the average size of the accidents were much bigger than average.

One year can in other words differentiate quite a bit from another. Looking at five year averages give us a better picture. The number of fatal accidents remain relatively stable.It  has varied between 7 and 17 since 1990, but is averaging at 11.2 both throughout the entire 25 year period and during the last five years. The numbers of aviation deaths are however declining.

Just over 11 crashes a year means just under one per month. Or one in every three million flights. 

18,647 people have perished in just over 25 years. That gives an average of 738 per year, and an average of 65.7 deaths per accident. But there is a positive trend. The average annual number of fatalities per five year period is going down from 793 in 1990-1994, via 900 in 1995-1999, 730 in 2000-2004 and 724 in 2005-2009 to 540 in 2010-2014.

The number of deaths or number of accidents in any given year or any given five year period still does not give us the full answer. We also have to take into consideration the number of flights. Given the increase in flight numbers, flying is becoming even safer year on year.

Safer and safer
There were 37,4 million flights in 2014, the highest number ever. Given the low number of fatal crashes that year (7), you would statistically have to fly 5,342,857 times for every accident. The average of 2010-2014 is lower, but still better than any five year period before; One fatal crash per 2,925,000 flights. That means a 0.000034% risk. You have never been less likely to fly on a plane that will crash and experience fatalities. Safer than ever, but not guaranteed. Nothing is in life.

Compared to deaths caused by shotguns, airplane accidents barely registers. As many as 396,270 people were killed by guns in homicides world-wide in 2012 alone, according to UNODC. And while we are at it, let's compare with another mode of transport. At least 1,240,000 people, are killed every year in accidents on the world's roads, according to Wikipedia.  

Your odds of dying from other causes (in the US) are much higher, according to The Economist:

Walking: 1 in 54,538
Fire: 1 in 104,524
Alcohol: 1 in 150,681
Falling down stairs: 1 in 157,300
Biking: 1 in 340,854
Storm: 1 in 2,271,454
Flying on a commercial airline (worldwide): 1 in 2,925,000
Lightening: 1 in 10,495,684
Dog bite: 11,273,142
Bee/wasp sting: 1 in 26,364,571
Fireworks: 1 in 50,729,141
Asteroid impact: 1 in 74,817,414

Or, let us look at leading causes of death per 100,000, worldwide. Heart and blood vessels diseases is worst by far with 268.8 deaths per 100,000 followed by infectious and parasitic diseases (211.3 in 100,000), ischemic heart disease (115.8 in 100,000), cancer (114.4 in 100,000) and stroke (88.5 in 100,000).

Other selected causes of death, per 100,000:
HIV/AIDS: 44.6
Tubercolosis: 25.2
Malaria: 20.4
Suicide: 14.0
Road accidents: 19.1
Measles: 9.8
Violence: 9.0
Falls: 6.3
Drowning: 6.1
Poisoning: 5.6
War: 2.8

Deaths caused by crashes on commercial airlines occur 0.019 times per 100,000 passengers (2010-2014).

Five year periods and used data
Deaths: 2,700, an average of 540 per year
Fatal accidents: 56, an average of 11.2 per year

2010-2015 (until March 28, 2015, including Germanwings flight 9525)
Deaths: 2,912, an average of 554.7 per year
Fatal accidents: 58, an average of 11.05 per year

Deaths: 3,619, an average of 723.8 per year
Fatal accidents: 64, on average 12.8 per year

Deaths: 3,649, an average of 729.8 per year
Fatal accidents: 48, an average of 9.6 per year

Deaths: 4,501, an average of 900.2 per year
Fatal accidents: 57, an average of 11.4

Deaths: 3,966, an average of 793.2 per year
Fatal accidents: 57, an average of 11.4 per year