Any idea what the definition of accident is for either of these organisations? The Boing numbers are on average 2x higher than ASN's and also show more fluctuation. BAAA (whoever that is) must be counting completely different events...
Slast has it mostly covered. The only thing I'll add is that the ASN numbers only consider civil aircraft capable of carrying 14 or more
passengers.
In summary:
- Boeing stats are the most restrictive, only considers civil aircraft > 60,000 lbs MTOW
- ASN stats include civil aircraft carrying 14 or more passengers
- BAAA stats further include civil and military aircraft with 6 or more total seats
In 40 years that 1974 data has barely changed.
Don't let the graph-scale fool you!! The Boeing accident data after mid-1970s looks stable only because the prior accident rate was so bad they skewed the chart!
But if we could "zoom in" we would see that the accident rate has continued to dramatically improve over the years. E.g., in the 1990s the accident rate still hovered around 1 per million departures, while fast forward to 2010 the rate has dropped to around 0.4 per million departures. That's a ~ 60% reduction just from the 90s!
(Consider that we now have 30+ million commercial departures per year!)