On a clear winter night, the jetliner begins a normal descent for landing. The descent profile is loaded into the flight management computer. Air traffic control (ATC) asks the crew, “Airport and traffic in sight?” Visibility seems assured. “Cleared for the visual to Runway 26, follow company traffic 5 miles ahead,” the controller directs. The first officer responds, “Cleared for the visual; we will follow company.” As long as they monitor the speed and do not overrun the company flight, this will be routine.
As expected, the altimeter smoothly unwinds and the crew comments on the clearness of the desert sky. Suddenly … where did the runway go? It was there a moment ago. “CAUTION TERRAIN,” the synthetic voice calls out. Terrain? The crew is certain their airplane is well above the ground. This must be a nuisance alert. “TERRAIN AHEAD, PULL UP!” Quickly the captain disengages the autopilot, increases thrust and begins to climb. Only then do both pilots realize how close to the ground they were. The mountains recede and the airport again becomes visible. The mountains were between the jetliner and the airport but completely dark.
This controlled flight into terrain (CFIT) accident did not happen.
For many years, CFIT accidents were the leading cause of fatalities in commercial aviation. A new technology, the ground-proximity warning system, which arrived in 1995, could predict the threat and warn the crew in time to react. Other types of accidents were reduced by predictive technology. Predicting a wind shear before the airplane encountered it became possible, and fewer accidents resulted, as in this example:
The jetliner is slowed in anticipation of possible turbulence. Numerous thunderstorms are in the area, but other flights are successfully landing. On the weather radar, the intended flight path looks clear. The captain and first officer have seen days like this many times before, but they are cautious. ATC carefully threads the flight between the storms. The final approach course is clear. “Turn right heading two one zero, maintain two thousand five hundred until established, cleared for the ILS [instrument landing system approach to] Runway one eight right,” the controller directs. The crew acknowledges the clearance and listens carefully for any comment from the preceding corporate jet. Suddenly, “WINDSHEAR AHEAD, WINDSHEAR AHEAD,” the synthetic voice calls, and the weather radar now displays a large red danger area. Both pilots recognize that weather is radically changing. They climb the jet and turn it away from the developing wind shear.
This potential wind shear accident did not happen.
A third example of commonly used predictive technology is the traffic-alert and collision avoidance system (TCAS). TCAS monitors the altitude and direction of other aircraft for any threat. If a threat is predicted (based on projected trajectory), then a climb or descent instruction is issued to the flight crew to avoid the oncoming aircraft.
Thanks to TCAS, many potential midair collisions do not happen.
Imagine predicting the impending failure of components prior to failure.
In that case, the catastrophic engine failure of Qantas Flight 32, an Airbus A380, near Singapore in November 2010, could have been predicted. Technology is rapidly developing that will be able to make such a prediction. Its cost may be justified by improvement in reliability and operational efficiency. Safety and economics can mutually benefit.
Along with crew resource management, upset recovery training and fatigue management, we should expand predictive technology to increase the number of accidents that do not happen.
Capt. John Cox is the chief executive officer of Safety Operating Systems. He is a 42-year aviation veteran with experience as a corporate pilot, airline pilot, instructor, test pilot and safety professional.