You know you should back up your data for redundancy. But you can’t back up an entire airline industry. That’s
a lesson we learned recently when a volcano with the cat-crossing-the-keyboard name of “Eyjafjallajökull”
exhaled tons of volcanic dust into the clear skies over Europe and brought aviation worldwide almost to a literal grinding
halt, disrupting commerce in general and even pushing some firms into bankruptcy.
Heathrow, England’s foremost airport and one of the world’s busiest, all but shut down. It might seem that flights
could just be rerouted through other airports, the way Internet packets are redirected around bad nodes, but alternate airports
couldn’t begin to handle the load.
It was reminiscent of the major power blackout that afflicted Canada and seven East Coast states in 1965, all due to one
mis-set safety relay. In that case, as one station failed due to excess loading, it threw that load onto adjacent stations,
which also failed, cascading to widespread electrical failure over an entire region. Sometimes redundant backups are too expensive
to build and maintain, so when the main systems are disabled we just have to live with the pain until they can be repaired.
Organizations aren’t blind to the consequences of disaster. Some companies’ disaster-recovery plans include equipping
an empty standby office. Others arrange for computer networks that literally replicate every keystroke to a remote location,
so if the primary location fails, the backup can swing into action within seconds. But this kind of extreme preparation is
rare, and for good reason; disasters are rare events.
The recent airline shutdown is a case in point. Rare, and catastrophic, but still not bad enough to justify building an entire
Heathrow-sized airport away from Northern Europe as a standby.
Volcanic ash blowing in the wind might not seem like a catastrophe, but it is. To see why dust is such a big concern, you
need to know how a jet engine operates. The engine’s core is a fiery chamber where jet fuel is burned to drive the multiple
fan blades you can glimpse when you look into the front opening. Everything about a jet engine is intense and precise. There
may be up to 900 blades in a jet engine, spinning at 30,000 RPM, and the combustion temperature can reach 2,700 degrees. Any
tiny defect in a blade at that speed can make it snap off and shear right through the engine cowling and anything else nearby.
There is small margin for error.
Volcanic dust presents two dangers to engines. The dust is primarily made up of silica, a form of glass, with sharp edges
that can nick and shred metal parts as it whizzes into the engine at nearly the speed of sound. It doesn’t just seek
out engines, either. The stuff degrades anything on the outside of the aircraft, including windshields and seals.
The other problem is that the high temperatures within the engine melt the silica and allows glass droplets to form inside
the engine parts. These can foul the tiny fuel nozzles and unbalance turbine blades. Together, all these effects can quickly
disable an engine and leave an aircraft plunging powerlessly toward the ground.
These aren’t theoretical risks. In 1982 a British Airways 747 sucked volcanic ash into its engines over Indonesia and
was just barely able to make an emergency landing. A KLM airliner in 1989 was flying over Alaska when it too hit an ash cloud
that had risen all the way to 26,000 feet. Smoke and ash were drawn into the cockpit, forcing the crew to don oxygen masks,
while the engines were disabled by the ash. In 1991, Mount Pinatubo in the Philippines went off, damaging 17 aircraft around
the area, some more than 600 miles away.
Alaska Airlines has faced that state’s frequent eruptions for decades, and has devised a way to cope with them. It
combines computer models of wind patterns with actual experimental flights to find clear air. It’s expensive, but unavoidable
given how frequently Alaskan volcanoes erupt. Estimates run between one and two eruptions per year, from up to 54 still-active
Of course, no crisis is so bad that nobody benefits from it. Teleconferencing companies reported a big upswing in remote
conferences during the volcano shutdown. Within a couple of days after the plume lofted into the atmosphere, Cisco Systems,
which offers teleconferencing, said that all of its rooms were booked.
The teleconferencing industry has been pitching itself for years as a low-cost alternative to air travel, and now it was
functioning not only as an alternate way to meet, but as the airline industry’s backup system. The telecommunications
systems in their turn are also redundant, using both satellites and undersea cables. You can’t be too careful.•
Altom is an independent local technology consultant. His column appears every other week. He can be reached at firstname.lastname@example.org.