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.
