A couple of recent threads have highlighted the recent upsurge in Cirrus fatal accidents. To help visualize what has been happening, let me post updates to the charts that I prepare for the plenary session of CPPP that discusses General Aviation and Cirrus accident statistics.
Cirrus Fatal Accidents By Quarter
First, the number of accidents over time. For convenience, I use 3-month quarter-years. This matches the GAMA production reports that are released each quarter. It also helps to differentiate accidents that occur in the summer months (April to September) from the dark days of winter (October to March). 70% of Cirrus fatal accidents occur in the winter 50% of the year. And you can see bunches of accidents that occur in those months with less daylight and worse weather.
Cumulative Cirrus Fatal Accidents
Next, the cumulative number of fatal accidents. Of course, this trends upwards since there is no way to reduce the cumulative total.
Cirrus Fatal Accidents Per 1,000 Airplanes
What is worrisome is seeing the cumulative number of fatal accidents accelerate over time. But so too is the number of airplanes delivered in the Cirrus fleet. So that gives us the next chart, the ratio of fatal accidents per 1,000 airplanes delivered.
Now we see both upward and downward segments over time. The downward trends occur when fewer accidents happen while the number of airplanes increases. The upward trends occur when more accidents happen at a rate faster than new airplanes are delivered. 2001 was a good year with few accidents. The time between 2003 and 2005 was good with the rate of accidents staying stable as the fleet grew. However, late 2006 and late 2007 were horrific. Again, it is those winter months. The ratio grew from 6 to 8 fatals per 1,000 planes in 2006-07, and then grew again from 8 to 10 fatals per 1,000 planes in 2007-08. So far in the first 2 months of the winter of 2008-09, we are holding even . . .
Cirrus Fatal Accident Rate Per 100,000 Flying Hours
Then there is the flying time rate. This is the rate used by the FAA and NTSB to calculate the number of fatal accidents per 100,000 hours of flying time. The GA fleet has about 500 accidents in 24,000,000 hours of flying time. The GA rate has declined from 1.33 in 2002 to 1.19 in 2007.
Fortunately, for COPA, Cirrus Design gives us the flying hours for the SR2X fleet. That enables us to plot this final chart. The fatal accident rate is calculated for each quarter from the actual number of fatal accidents and interpolating the flying time for that quarter.
In the early years, a few accidents cause big swings in the rate. The first single accident in 2001Q2 caused a jump to 4.5 accidents per 100,000 hours, but the fleet was only 200 airplanes that had flown only 25,000 hours.
The next jump to 4.5 was from 3 accidents in 3 months ending in January 2003 while the fleet was still small, less than 800 airplanes that had flown less than 200,000 hours.
Yet, the last year has seen 13 accidents and the rate has barely climbed to 1.8. Now the fleet has over 4,000 airplanes that fly about 800,000 hours a year. So that's stabilizing the rate.
That short green line? If you take away from the GA accident rate all of the multiengine and turboprop/turbojet airplanes, I calculate the GA single-engine piston rate to be about 1.86 fatal accidents per 100,000 flying hours.
So that is a tutorial on accident rates based on the Cirrus fatal accident history.
Obviously, COPA wants to reduce the number of accidents by eliminating all of the pilot causes. Just pulling the parachute more often would help. But talking to other Cirrus pilots about flight safety will also help.
Cheers
Rick
Posted
27 Nov 2008 15:11
by
Rick Beach