Aviation safety issues and actions
Recommendation issued to: Civil Aviation Safety Authority
|Date issued:||28 January 1998|
|Safety action status:|
The Bureau of Air Safety Investigation recommends that the Civil Aviation Safety Authority reconsider the conditions of the current exemption to CAR 258 as it applies to passenger-carrying charter operations in single-engine land aircraft with a view to: (a) minimising the likelihood of a ditching event; and (b) minimising the risks associated with the outcome of a ditching event.
|Date issued:||20 April 1999|
|Response from:||Civil Aviation Safety Authority|
CASA has no further comment on this report.
The following correspondence was forwarded to the Civil Aviation Safety Authority on 13 December 1999:
Thank you for your response to recommendation RI 9970176, dated 20 April 1999, relating to overwater operations in single-engine aircraft. That recommendation was issued to CASA on 28 January 1998 and stated the following:
R199 70176 - The Bureau of Air Safety Investigation recommends
that the Civil Aviation SafetyAuthority reconsider the conditions
of the current exemption to CAR 258 as it applies to
passenger-carrying charter operations in single-engine land
aircraft with a view to:
Response classification - OPEN
As CASA stated only that "CASA has no further comment on this report", the Bureau does not consider that that response adequately addresses the recommendation. There was no indication of CASA's acceptance, partial acceptance or rejection of the recommendation nor was any justification provided to support CASA's position on the matter. In addition, there was no evidence to suggest that CASA had reconsidered the current exemption clause in CAR 258.
In order to finalise this matter, the Bureau requests that CASA reassess the recommendation and provide a further response as soon as possible. A copy of the recommendation is attached.
|Date issued:||13 June 2000|
|Response from:||Civil Aviation Safety Authority|
I refer to your letter of 13 December 1999 concerning R1 9970176. The only extensive study that seems to have been done of single versus multi-engine accidents in water in Australia was the Berick Report of 1993. Because the flight hours that aircraft spend operating over water is not recorded, it is not possible to determine risk rates for various aircraft categories. Therefore, Berick's study,which was based on 114 BASI reports of accidents in water from 1969 to 1990, could not draw definite conclusions about the safety of single versus multi-engine operations.
AIRCRAFT CATEGORY WATER ACCIDENTS FATAL IN WATER
Single engine land plane 41 14
Multi engine land plane 14 8
TOTAL 114 30
Only 18 of the 92 single engine accidents were ditchings; the rest were uncontrolled descent into water. In other words, while about 80% of single engine accidents were uncontrolled, less than a quarter were fatal. F9or multi engine accidents, only half (11 out of 22) were uncontrolled desent into water, yet 40% were fatal.
Many accidents happened on takeoff or landing: only a handfull of singles and twins accidents occurred more than 15 NM from land.
There were no fatal single engine land plane charter accidents in water. Of the five fatal charter accidents, two were in multi-engine land planes and three in single engine float planes and amphibians. Note that the time period studied did not include the Seaview, Aquatic Air or Whyalla Airlines accidents.
On this basis, and in the absence of data on flight hours over water for aircraft categories, it would be difficult to sustain the argument that operations over water are significantly safer in multi-engine aircraft than in singles, especially given the relatively high proportion of multi-engine water accidents that were fatal.
It also implies that the analyses that CASA did comparing single engine turbine aircraft with piston twins for the Single Engine IFR and ASETPA projects may have underestimated the likelihood of accidents in piston twins following an engine failure, compared with single turbines. In other words, the single turbines may be more than the four or five times safer than CASA predicted in it's analyses.
The following correspondence was forwarded to the Civil Aviation Safety Authority on 27 July 2000:
I refer to your letter of 8 June 2000 concerning recommendation R1 9970176, issued on 28 January 1998.
The Bureau had recommended that CASA reconsider the conditions of the current exemption to CAR258 as it applies to passenger-carrying charter operations in single-engine land aircraft.
The information contained in your letter refers only to fatal accidents and comparisons between single-engine and multi-engine aircraft. The central safety issue of R19970176 is the potential consequences of a ditching event in a single-engine aircraft that is not suitable for landing on water. The statistics presented do not clearly indicate how many ditching events occurred in single-engine land aircraft and how many of those resulted in injuries or fatalities.
The practices of other countries suggest a recognition of the
inherent risks associated with operating single-engine land
aircraft over water (refer text of original recommendation
attached). CASA has made no comment on this aspect.