How dangerous are helicopters?
"The London skyline has changed hugely over the last few years. The number of helicopters flying have increased a great deal." Kate Hoey, The World At One, BBC Radio 4, January 16, 2013
Though the precise causes of yesterday's helicopter crash in Vauxhall - which resulted in two fatalities - are yet unknown, MP Kate Hoey seemed to suggest on Radio 4's The World At One yesterday that an increase in the number of helicopter flights had made the London skyline less safe.
She was challenged by Martha Kearney who retorted "if you look back at January 2007 there were 67 [helicopter flights] per day, whereas January last year [there were] 33 per day." Though Ms. Hoey admitted her source was "apocryphal stories," she added that there was no doubt about the increase.
The MP for Vauxhall also raised the issue in Parliament yesterday, and exhorted the government to "look much more closely at where, how and why helicopters fly through our central city." The Prime Minister agreed that "it is inevitably something that has to be carefully looked at."
But is it true that the number of helicopter flights have been increasing in the last few years? And how dangerous are helicopters exactly?
Figures released by the Civil Aviation Authority (CAA) - and also published by the Guardian - reveal that in December 2007, the London skyline saw an average of 58 helicopter flights per day. June 2008 saw a peak of 4,310 flights, or an average of 143 per day.
In December 2012, there were on average 36.5 chopper flights per day.
It is clear from the graph below that monthly flights over London Heathrow and London City control zones decreased fairly consistently in the year 2012, as compared to the past five years.
How dangerous are helicopters compared to other forms of transport?
Yesterday's incident was the first fatal helicopter incident in London since records began in 1976. The Civil Aviation Authority also told us that, nationwide, there have been 33 fatal civil helicopter incidents since 1998. This is out of a total of 16,354 chopper flights for the year 2012, up to and including Octoer 2012.
The European Aviation Safety Agency publishes an Annual Safety Review. In their 2011 report it emerged that out of approximately 100-120 civil helicopter accidents a year in Europe, an average of 16 fatal accidents were reported per year between 2006 and 2009.
So how does this safety record compare to other modes of transport?
While we know that in 2011 32 people died in cars in London, and that 16 died on their bikes, this doesn't tell us anything about whether road fatalities are more likely to occur than helicopter fatalities.
In fact, the data released by the European Aviation Safety Agency, the Civil Aviation Authority, and other organisations which concern themselves with aviation safety, isn't directly comparable to other accident data as it doesn't account for the different distances covered by the different modes of transport.
On the other side of the Atlantic, Slate.com attempted to answer this question after New Jersey Governor Chris Christie argued that his use of taxpayer-funded helicopter flights was justified because they had a better safety record than cars.
Slate journalist Brian Palmer observed that:
Between 2005 and 2009, there was an annual average of 1.44 fatalities (PDF) per 100,000 flying hours in non-military helicopters. Over the same period, there were 13.2 traffic fatalities per 100,000 population in the United States annually. Since the average American spends around 780 hours per year (PDF) in the car, that means the fatality rate per 100,000 hours of driving time is just 0.017. Based on hours alone, helicopters are 85 times more dangerous than driving. [Emphasis added]
This is of course a back-of-the envelope calculation which doesn't compare like with like.
So while we don't have enough comparable data to form firm conclusions about the relative safety of helicopter travel, it does seem that Kate Hoey was mistaken about increases in their use in the capital, at least in recent years.
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Flickr image courtesy of johan wieland