Accident stats

[Hoveronly]

Can anyone point me towards a website where I can access stats which support the theory that 500, 1000 and 2000hrs (?) are proven danger (accident prone) points in a piolts experience. I know that if no one flies on the last Friday of the month there wouldn't be any accidents - or so I was told at a briefing (in jest) once!

Heads up!

[i4iq]

Try using the search tool for Statistics - the subject has been discussed in a number of ways.

Lots of Stats available on the FAA web site.

[Hoveronly]

Thanks, tried but failed!

[NickLappos]

You won't find any such facts because they aren't true.
Here is the data you safety guru didn't have. Of course, the great number of accidents for the higher hours is just the sum of all those hour levels:

http://www.aopa.org/asf/publications/06nall.pdf page 16

http://webpages.charter.net/nlappos/accidenthours.jpg

[Torquetalk]

Not sure if the greater no of accidents in the higher hours grouping does reflect the sum of all those hours Nick.

Perhaps I am missing the point, but the AOPA report would appear to be a simple snapshot of accidents over a given period broken down by TT of the pilot. AOPA make the point that in the population involved (GA fixed wing in the US), the number of hours flown is highest and may not reflect inexperience but simply increased exposure.

Seen in this light, the high timer peak (in this population) might suggest the highest risk group of all. But perhaps that was the point you were making.

Whatever is generally held to be true, these stats don't appear to support it

TT

[i4iq]

I wonder which stats the insurance companies use...

[NickLappos]

Torquetalk,

Please don't misread the chart. The hours column is the pilot's flight time at the time of the accident (for fatals, it is also the maximum flight time, BTW - Duh!). The percent column is the % of all accidents that that hour group experienced. Thus, 15.7% of all accidents involve pilots with 501 to 1000 hours.

At no time does a pilot see a RISE in accident rate at a higher flight experience time, a "fact" that is directly implied by the foolish statement that there are "danger points" at higher hours.

The big percentage of accidents for pilots with more than 4000 hours is because the stats were not run out to big, big numbers at the same granularity as they were for the lesser flight hours.

[Graviman]

Once again it looks like the exponential decay model of "faults per hour" fits...

Mart

[Shawn Coyle]

Also worthy of note is that the data is often incomplete for NTSB investigated accidents, and if it involves someone with multiple ratings (FW, RW, etc), then it may not break that into appropriate bits.
Flight instruction for low time instructors is not considered, etc.
And the number of ratings and licenses held is also not considered - I worked on a case where the pilot had nearly every rating known to the FAA, but not the magic number supposedly required by the insurance company. As he had passed all the necessary checkrides, it was relatively easy to prove he had demonstrated the same level of competency that someone with more hours would. (and the actual cause of the accident wasn't even considered, nor was whether more experience would have made any difference).
Accidents and statistics should be considered mutually exclusive things unless you can see all the data.

[Torquetalk]

Nick,

It was a rash interpretation; I had completely overlooked the gross grouping of high timers. :O

TT

[i4iq]

http://www.faa.gov/library/manuals/aircraft/media/faa-h-8083-21.pdf

Page 144 seems to suggest there is a blip (accident point) at 2,000 hours TT for NVFR

[NickLappos]

i4ig,

I would bet that is not real data, the chart is being used in that case as an example of how to chart data.

[i4iq]

Nick

It certainly doesn't tie up with the data you present. In which case I think the FAA publication is a little misleading as on the previous page it seems to be referring directly to the data as represented in the chart.

"For example, the accident rate decreases by nearly 50 percent once a pilot obtains 100 hours, and continues to decrease until the 1,000 hour level." (Possibly not referring to the data in the chart)

"The data suggest that for the first 500 hours, pilots flying VFR at night should establish higher personal limitations than are required by the regulations... Figure 14-4]"


I also seem to recall a chart from elsewhere with a similar blip - who knows, perhaps this is how the urban myth about TT blips started!

[puntosaurus]

It's possible that the answer here is down to the specific subset of accidents being examined, ie. Night VFR, and the nature of missions being performed.

Sub 1000 hours it's possible you're looking at pilots steadily improving in airmanship and competence at night, until they get enough hours to qualify for jobs in a known high risk category, eg. HEMS. The numbers are sufficiently small in this high time pilot category for a small change in mission mix to have a large effect on the stats.

One of many possible explanations I'm sure !

[widgeon]

I guess there is some truth as the chart shows a 500 hr pilot is 20% higher rate than a 501 hr pilot ;) . I guess there are some white knuckle moment as you approach 500.9 hrs