SUBJECT - REGIONAL AIRLINE AIRCRAFT OPERATING ABOVE MAXIMUM
WEIGHTS
INTRODUCTION - REGIONAL AIRLINES SAFETY STUDY
Between October 1995 and July 1997, the Bureau of Air Safety
Investigation undertook a study of the safety of Australian
regional airlines. The objectives of this study were to:
(a) identify safety deficiencies affecting regional airline
operations in Australia; and
(b) identify means of reducing the impact on safety of these
deficiencies.
For the purpose of the survey, regional airlines were grouped
according to the number of passenger seats fitted to the largest
aircraft operated by that airline in January 1997. The groups are
defined as follows:
(a) Group 1: 1-9 seats;
(b) Group 2: 10-19 seats; and
(c) Group 3: more than 20 seats.
The study involved analysing data obtained from:
(a) responses to a survey of Australian regional airline
employees;
(b) discussions with Australian regional airline employees and
managers; and
(c) air safety occurrence reports involving regional airlines over
a 10-year period (1986-1995) from the BASI database.
This recommendation addresses one of the safety deficiencies
identified as a result of this study.
SAFETY DEFICIENCY
Some regional airline aircraft are flown at weights above their
prescribed maximum take-off weight.
FACTUAL INFORMATION
Survey results
Pilots were asked whether they operated their aircraft at weights
above the maximum take-off weight (MTOW). To this question, 85% of
pilots answered "never", while 15% replied that on some occasions
they did operate above MTOW. Pilots answering that they sometimes
operated their aircraft over its prescribed maximum take-off weight
were predominantly from Group 1 or Group 2 airlines.
A summary of responses to this question can be found at attachment
1.
When asked to describe a safety incident, flight crews described
aircraft operation above MTOW as the second most common incident.
In response to the question asking respondents to state what they
thought was the greatest safety issue facing regional airlines, two
common answers given by flight crews were overloaded aircraft and
aircraft with poor or doubtful climb performance. These two issues
are different aspects of the same safety problem.
The survey indicated that overloading of aircraft was not isolated
to individual acts of wilful behaviour. Anecdotal evidence
suggested that overloading can sometimes occur when adverse weather
conditions require additional fuel. On those occasions when there
is a full passenger load, the addition of extra fuel without
offloading passengers or cargo has resulted in maximum weight
limits being exceeded.
"Overloading is a recurring problem despite recent Civil Aviation
Safety Authority (CASA) initiatives. The problem is mainly with low
capacity regular public transport (RPT) aircraft where pilots,
although instructed not to overload, are presented with situations
beyond their control by the airline booking system. Additionally,
there is no explicit company policy on load rejection, for example,
"last booked, first off". Bookings are predicated on the maximum
seat capacity for the type and often no allowance is made for
passengers carrying the maximum baggage allowance, or for those
circumstances where weather conditions exist that require a flight
plan to an alternate aerodrome and where additional fuel must be
uplifted for the diversion or holding."
-Pilot, respondent 552
Commercial pressures were also cited as directly contributing to
instances of aircraft overloading.
Aircraft weight issues
Limits are placed on aircraft take-off weights for the following
reasons:
(a) so that structural limits of major aircraft components such as
landing gear are not exceeded; and
(b) so that aircraft are able to climb clear of obstacles
(particularly following takeoff), in accordance with prescribed
regulations, and can maintain a safe altitude in the event of an
engine failure.
Aircraft performance
Climb performance is degraded in overloaded aircraft, to the extent
that safe clearance from terrain may not be able to be maintained.
This is a particular safety concern in many twin-engine aircraft
that have experienced an engine failure.
Many smaller twin-engine aircraft operated by regional airlines, do
not have to meet the "one-engine inoperative" performance
requirements that must be met for certification of larger
transport-category aircraft. This effectively means that there is
an accepted period of risk during the takeoff and the initial climb
phase of flight. If an engine failure were to occur during this
phase of flight, climb performance would not be guaranteed.
Responsibility for correct loading
Responsibility for ensuring that an aircraft is not overloaded
rests with both the airline and the flight crew. As part of the
compliance statement for the issue of an Air Operators Certificate,
the Civil Aviation Safety Authority (CASA) requires an applicant to
produce weight and balance documents and loading instructions in
the company's operations manual.
Civil Aviation Regulation (CAR 235) requires that aircraft weight
and loading is within permissible limits prior to takeoff. To
comply, flight crews must complete a trim sheet or load statement
that includes all items of load. A copy of this document must be
left at the point of departure and another copy must be kept by the
airline for three months. These documents have to be made available
for inspection by CASA staff on request.
Pressure to overload
Despite the considerable penalties imposed on both airline
operators and flight crews when aircraft are found to be
overloaded, the commercial pressure to meet contractual obligations
has been great enough in some circumstances, and the risk of
detection sufficiently unlikely, to justify the occasional breach
of regulations.
Evidence provided in the commission of inquiry into the relations
between the Civil Aviation Authority and Seaview Air, known as the
"Staunton Report", supports this view:
"The problem was, for example, that as I might have eight
passengers from Sydney who had booked some time before and were
excited about going on their holiday and there were perishables
sitting there to be taken to Lord Howe, what do I leave behind?
Even though the aircraft could physically carry the passengers and
freight, it would still be overloaded".
Lack of alternative travel options may make it awkward for the
smaller regional airline operator to offload booked passengers or
cargo. Anecdotal evidence suggests that airline operators have
exploited this situation, resulting in enormous pressure being
exerted on flight crews to overload their aircraft.
Comments from some of the surveyed flight crews suggested that in
certain circumstances, company pressure was applied to accept the
extra load and falsify the load documentation.
"Before this particular flight, I knew a full load of passengers
were booked. I asked the managing director the company's policy
regarding offloading should all the passengers arrive with their
allocated 12 kg of baggage, as this places the aircraft well above
MTOW. His response was "are you telling me something we've done for
years, we can no longer do?". It was made very clear that my
decision should not be made with regard to aircraft safety but to
continued employment with the organisation."
-Pilot, respondent 404
"Overloading. Often the load on the aircraft does not match the
paperwork given to me by the traffic officer in charge of loading
the aircraft. Management tend to turn a blind eye to
overloading."
-Pilot, respondent 178
Surveillance
Ramp checks are carried out as part of CASA's Aviation Safety
Surveillance Program of airline operations. Unscheduled
surveillance is used as one means of assessing an airline's "safety
health". Each district office manager determines the frequency and
focus of these inspections, depending on a number of "trigger"
factors such as incidents, reports, complaints and other safety
intelligence information.
ANALYSIS
Airline operators and flight crews have overall responsibility for
ensuring that aircraft are not overloaded. Overloading aircraft, by
even small margins, may expose flight crews and passengers to risks
of unacceptable proportions, particularly during the critical
phases of takeoff and initial climb. CASA's role is to check the
adequacy of any loading procedures and ensure that these procedures
comply with prescribed requirements. In the conclusions to Chapter
6 ("Pressure to Overload") of the Staunton Report, the comment is
made that "some reliance must be placed on the operator to develop
appropriate procedures and adherence to those procedures".
A load rejection policy is one way of achieving this. Such a policy
would provide flight crews with a published procedure that would
contain explicit and unambiguous directions as to the manner and
priority for offloading passengers or cargo, when circumstances
require such action. The development and application of such a
procedure would provide unequivocal management support to a flight
crew's decision to offload passengers or cargo, in order to avoid
overloading aircraft. Subsequently, real and/or perceived pressure
on crews to overload aircraft may be reduced.
A "load rejection" policy should be contained in the company's
operations manual and be part of an AOC approval.
In view of the number of respondents to the survey who alleged
overweight operations, the frequency and depth of surveillance may
be insufficient to prevent repeated occurrences of
overloading.
