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.
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:
(a) minimising the likelihood of a ditching event; and
(b) minimising the risks associated with the outcome of a ditching
event
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.
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
Single engine float plane 37 5
And amphibian
Single engine helicopter 14 2
TOTAL SINGLE ENGINE 92 21
Multi engine land plane 14 8
Multi engine float plane 4 0
And amphibian
Multi engine helicopter 4 1
TOTAL MULTI ENGINE 22 9
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.
Therefore, the Bureau requests that R19970176 be reconsidered and
that CASA provide advice on the outcome of any further
consideration at your earliest convenience.
