In the end it should not make a huge difference which criteria you use, since the trends should be roughly similar. Interestingly, the short term trend (2010-2011) seems to differ between Flight’s and ASN’s data.
Perhaps we can conclude that, based on our data, aviation has become safer for the “larger” airliner segment, but that there is an increase in smaller aircraft accidents in the “air taxi” segment.

Harro.

I’ve posted some observations and questions on David Learmont’s blog post http://www.flightglobal.com/blogs/learmount/2012/01/to-an-even-greater-degree-than.html although as yet it hasn’t appeared online (I’m assuming it is still in the queue to be approved), and I would like to post it here too:

It is interesting to note the different methodologies used by Flight ( http://www.flightglobal.com/Features/safety-review-2011/fatal-accidents/ ) and by the Aviation Safety Network ( http://aviation-safety.net/database/year.php?year+2011 ) yields different pictures. Flight talks of 2011 showing on increase in fatal accidents compared to 2010 (32 vs 26), while ASN talks of 2011 showing a reduction in fatal accidents compared to 2010 (28 vs 29). Digging into the numbers for 2011, Flight has counted 6 single-engine aircraft accidents, whereas ASN only counts multi-engine aircraft where the base model is certified for 13 or more passengers. This accounts for 6 accidents recorded by Flight but not by ASN (4 July Missinippi Airlines Cessna 208B, 23 September Servant Air DHC-3, 4 October Air Tindi Cessna 208B, 2 September Grant Aviation Cessna 208B, 9 September Susi Air Cessna 208B, 23 November Susi Air Cessna 208B). It also seems Flight has not counted three accidents which were counted by ASN: 05 March VASO Antonov 148, 08 March Desert Sand Aircraft Leasing DHC-6, 1 April Fugro Aviation CASA C212. Presumably these weren’t by Flight due to the test/air work nature of the flights? Also, while Flight said it recorded 32 fatal airline accidents, the published list only contains 31 (4 scheduled passenger, 18 non-scheduled passenger, 9 non-passenger). I don’t know whether there was one left out by mistake, or if the number should be 31 rather than 32.

I’d be interested to hear some comments on the differing methodologies, and why one or the other may or may not be more relevant to someone trying to form an overall view of the safety picture for 2011. In particular, I’m wondering whether the capture of the 5 Cessna 206B and 1 DHC-3 accidents (as done by Flight) or the exclusion of single-engine aircraft accidents (as done by ASN) paints an accurate picture. I have asked on David Learmont’s blog what the lower limit for inclusion in their statistics was, because I notice three accidents involving large single-engine aircraft were not included there: the 31 March Black Sheep Aviation DHC-3 accident in Canada, the 22 August Sayanian Cedar An-2 accident in Russia, and the 14 October Moremi Air Cessna 208B accident in Botswana.

Nick