Beyond the Black Box

A glass box must make the most of limited bandwidth. Just as graphics-display programs leave untouched those pixels that depict a clear blue sky while reserving most of their processing for the pixels that depict drifting clouds or darting birds, a glass box might transmit only the parameters that show significant deviation from a previous sampling. Another trick is to hold back some data whenever bandwidth is tight and then transmit data when bandwidth becomes available again.

It would be unwise to delay transmission by first running flight data through an onboard recorder before transmitting it to the ground. One way around the problem is to add a port to the onboard recorder, so that logging of data could proceed on board and on a ground-based server simultaneously.

Once the data are logged on the ground, expert systems could sift through vast troves of historical information to spot abnormal and possibly catastrophic behaviors. Designing these systems is the main challenge, for it goes beyond just juggling data—such a system must emulate human judgment. Yet this wouldn't be too hard to accomplish. After all, the expert system need not be omniscient; it would be enough if it merely caught the attention of air-traffic controllers, alerting them to possible trouble.

Because the volume of data that must be saved amounts to hundreds of gigabytes per day, it may be necessary to save only select samples of it. Armed with such compressed data, expert systems and human experts working in tandem could identify recurring errors due to design problems, maintenance problems, pilot training, weather conditions, and airport or runway conditions. The knowledge gained could also be used for training pilots, air-traffic controllers, and accident investigators.

It has been a decade since I first proposed the glass box, and progress toward it has been shamefully slow. The main hurdle is sheer institutional inertia. The strongest institutional opposition has come from airline pilots, who fear that the practice would lead to full-scale monitoring of their work, much as it has for interstate truckers. In 2000, in reaction to the EgyptAir crash, the FAA tried to mandate cockpit cameras, but the U.S. pilots' union managed to prevent it. The rest of the world, which followed the U.S. lead, has also done nothing.

Concern over privacy and professional autonomy need not be a sticking point. To assure the privacy of pilots, airline companies, and aircraft manufacturers, all you need to do is secure the communications between onboard and ground-based systems and to protect the saved data from prying eyes. Data encryption techniques seem more than adequate for this purpose; using a new encryption key each time an aircraft takes off could further enhance the protection. Remember, the point of the glass box is not to feed lawsuits but to enable professionals to learn from experience.

To keep sensitive information out of the hands of insurers, airline executives, and lawyers, it should be enough to emulate privacy policies already in place in the United States in other fields—for instance, the Health Insurance Portability and Accountability Act for patients' medical records. The glass-box system could achieve this goal by giving the firm that operates the ground-based systems exclusive rights to the data it stores.

I'm heartened to hear that Airbus, in France, is exploring these ideas, but one company cannot hope to change institutionalized practices in the world at large. The U.S. government's Next Generation Air Transportation System, under the control of the Joint Planning and Development Office, ought to take up the challenge.

The black box was good, in its time; the glass box is its logical successor.