Clouds, Computers and Composites: The New Crisis in Aviation

by Manuel Garcia, Jr., Counterpunch.org

The recent loss of Air France Flight 447, an Airbus A330-200, has raised many doubts among the flying public and even some aviation professionals about the safety of the newest generation of passenger airplanes. These new airliners have composite materials replacing metal for many structural elements and control surfaces, and they are reliant on computer-controlled flight and navigation systems.

Airbus and Boeing are today’s main competitors for new airplane orders worldwide. As noted earlier, it is the cost of fuel that drives the economics of commercial air transport, and in turn the replacement of older aircraft with newer models. The competing demands of safety, reliability, strength, carrying capacity, volumetric efficiency, speed and fuel economy drive airplane designers toward a convergence of characteristics, so that today both Airbus and Boeing airliners look, sound and feel largely the same to most passengers.
…..
Both the 787 Dreamliner and the A350 are nearly all-composite airplanes. The 787 Dreamliner is 80% composite by volume, and by weight it is: 50% composite, 20% aluminum, 15% titanium, 10% steel and 5% other. By weight, the A350 is: 53% composite, 19% aluminum and aluminum-lithium, 14% titanium, 6% steel and 8% other.
…..
The challenge facing the civil aviation industries today is to answer the questions raised by the mysterious loss of Air France Flight 447, and to convince the public that any problems that may be uncovered about the use of composites and computers in AF447 will be fully understood and solved before building and flying all-composite airliners with even more complicated computerized control systems.
…..
AF447 In The Clouds

In the early pre-dawn hours (~2:15 UTC) of 1 June 2009, Air France Flight 447 from Rio de Janeiro to Paris fell out of the sky into the Atlantic Ocean near the equator about midway between Brazil and Senegal, with the loss of all 228 people aboard. The aircraft was one of the most modern, a dual engine Airbus A330-200.
…..
At 2:10 UTC, the first of a series of automated signals was sent by AF447’s onboard computerized maintenance system, via satellite, to Air France computers in Paris logging maintenance information. The series of automated messages had a combined time span of 1 minute and occurred until 2:14 UTC; 5 failure reports and 19 warnings were transmitted. The earliest automated messages reported on the failure of the Pitot Tube sensors, which measure the airspeed of the airliner and provide an estimate of altitude based on the static pressure of the atmosphere. Subsequent messages in the initial burst indicated that the auto-pilot (automatic ‘steering’) and auto-thrust (automatic ‘gas pedal’) systems had been disengaged, the collision avoidance system (to detect other nearby airliners) had a fault, that the flight control computers (three for redundancy) had shifted to an “alternate” mode where they made fewer automatic adjustments to the airplane’s control surfaces, and placed fewer limits on the range of manual inputs by the pilots that would be implemented as motions of the control surfaces (ailerons, rudder and the many types of flaps).

From 2:11 UTC to 2:14 UTC, messages indicated the failure of the gyroscopes (air data inertial reference system, ADIRU, used to provide the artificial horizon orienting the sense of ‘up,’ ‘down,’ and ‘level,’ essential during nighttime) and resulting faults in the instrument panel displays (screens and electronic images instead of mechanical dial gauges); there was disagreement between systems that interpreted air data (such as for airspeed and angle of attack of the wings into the airflow); that a fault had occurred in the flight control computer system (that transmits commands to the hydraulic actuators that physically move control surfaces); that a fault had occurred in the computer system that captures and processes pressure and electrical outputs from air and motion sensors that supply data; and finally, a “cabin vertical speed warning” indicating a rapid loss of cabin air pressure, due to either a rapid descent or a breaching of the cabin shell.
…….  Full Article

The incident which befell Flight 447 has some parallels with incidents involving A330 aircraft flown by other carriers. Three similar reports are on file at the Australian Transport Safety Bureau (ATSB), with two incidents relating to Airbus A330 with the flight computer problems, plus one which involved a Boeing 777.  Wiki

DCL: It seems plausible that some CEP techniques such as event pattern detection and abstraction might be useful in automating real time analysis of automated signals from flight control computers. Patterns experienced in other flight situations might provide advisories to an in-flight crew before things get out of hand. And would certainly be useful post mortem.  This is a very thoughtful article with many references that those of us who fly often may find interesting!