David Learmount/LONDON
THERE WERE 305 deaths in world air transport during the first six months of 1995, but 150 of them were caused by hostile acts. With only 155 air-transport fatalities in operational accidents, however, the first six months of 1995 have been exceptionally safe. There were 23 fatal accidents, which sounds less encouraging, but ten of them were to non-passenger operations involving small aircraft. When traffic figures are known and accident rates can be fully analysed, it may turn out to be the safest first-half-year for airline passengers in air-transport history.
It was a bad six-month period, however, for fatal events caused by hostile action or illegal interference with aircraft safety: 150 people died in four events, three of which involved factions in local wars shooting down aircraft used in civil or civil/military air-transport operations.
When a Colombian McDonnell Douglas (MDC) DC-9 crashed in January, the Colombian Government said that it had been sabotaged, and the inquiry has not fielded any alternative verdicts since then. (This is not the first such incident: in November 1989, an Avianca Boeing 727 had been brought down by a bomb believed to have been placed by a drug-running cartel.)
Comparing operational fatal accident numbers in the respective January-June periods during the past 25 years, only the figures for 1984 are better than those for 1995 in terms of total fatalities, rather than rates. During the first six months of 1984 there were 134 deaths in 12 fatal accidents against 155 fatalities in 23 accidents in 1995. Since then, however, passenger numbers have increased by more than 50%, and departures by more than 30%. If passenger-traffic expansion is taken into account, therefore, the fatalities comparison makes January-June 1995 the safer of those two half-year periods.
Allowing for the increase in departures since 1984, however, January-June 1984 still remains "safer" than the corresponding period in 1995 for fatal-accident numbers. Since 1984, accident information from the former Soviet Union and some of the world's poorer countries has become more accessible - particularly information about accidents to small domestic carriers - so accident-number comparisons may be biased in favour of 1984.
Using interim investigation reports and basic information available so far, weather appears to be a causal factor in an unusually high 41% of the fatal accidents to passenger operations. Weather is always a factor in a significant proportion of accidents, but 20% would be closer to the average.
Also causing an unusually high proportion of the events in this half-year was engine failure. There were five engine-failure accidents, which is 21% of the total. All involved small airliners, three of them during passenger operations.
The most serious single accident of the year, however, began with a case of engine-power asymmetry which developed slowly, and which the crew failed to counteract. This was the Tarom Romanian Airlines Airbus Industrie A310-300 accident on 31 March. The interim report says that the cause was not engine malfunction, but was probably caused by a throttle lever which jammed while the autothrottle was engaged. Weather was almost certainly a secondary factor, because, in the prevailing conditions of cloud, falling snow and general white-out, the crew would have had no natural visual clues to the aircraft's changing attitude. It remains unknown, however, why they failed to react - until too late - to the flight- and engine-instrument indications and to the widening disparity in the throttle-lever positions.
Controlled flight into terrain (CFIT) is still very much an issue, despite campaigns by the industry, the Flight Safety Foundation (FSF) and International Civil Aviation Organisation to raise the level of airline awareness about its causes. Although fatal CFIT has applied only to one passenger flight so far this year, there were four such accidents to non-passenger operations, or 36% of all fatal accidents in that category. One of them (see table entry for 22 March, Union Flights) involved a localiser/distance-measuring equipment approach to a runway in bad weather. This is one of the step-letdown approach categories which the FSF warns are particularly CFIT-prone. Studies of the relationship between step-letdown procedures and CFIT have led to calls for increased trials of letdown procedures using global-navigation-satellite systems (GNSS) and flight-management systems, which the FSF believes are intrinsically safer.
In safety reviews, at least one accident sometimes looks as if it could have been avoided. When Air Transport International's MDC DC-8-63C (16 February) was being prepared for a three-engine ferry flight, the crew clearly had a warning that all was not well, because it aborted the first take-off attempt. The account of the second take-off attempt (see following table) is tragic.
This event raises questions about human factors - how many clues do aircrew need before they decide it is not safe to proceed, and what was the motivation for the crew seeming to "...press on regardless"?
Source: Flight International
