Near misses and close calls in the air

Not to scare anybody, but the number of near collisions between commercial aircraft is going up.
In the past year, according to the Federal Aviation Administration, the rate of what it considers "serious" airspace incursions in the United States rose from 2.44 per million flights to 3.28 per million flights. That works out to fewer than 10 incidents per year, but still the trend is a worrying one, especially as the number of lesser infractions has risen more sharply.
The news isn't entirely surprising. There are more planes flying than ever before, overseen by an air traffic control infrastructure that has not kept pace. And regional jets, which tend to fly short-haul routes at lower altitudes, in and out of busy hubs, now account for half of all commercial traffic. The terminal area -- airspace in and around airports, where collisions are most likely to occur -- has never been busier.
Pilot and controller organizations, together with the FAA, are taking this uptick very seriously. As they should. In the meantime, nervous fliers should be wary of alarmist media coverage.
In an Associated Press story making the rounds, reporter Joan Lowy writes, "In some cases, pilots made last-second changes in direction after cockpit alarms went off to warn of an impending crash."
The alarm she's referring to is part of a cockpit safety device called TCAS -- Traffic Collision Avoidance System, pronounced "Tea-Cass." Linked to the plane's transponder, TCAS gives pilots a graphic, on-screen representation of surrounding aircraft. If certain thresholds of distance and altitudes are crossed, it will issue progressively ominous oral and visual commands.
Personally I find TCAS to be needlessly complicated and over-engineered, but most important, it works. If two aircraft continue flying toward each other, their TCAS units work together, vocalizing a loudly imperative "Climb!" instruction to one, and "Descend!" to the other.

When the AP says "last-second," that's not to be taken literally in most cases. Response times vary. And "impending crash"? Probably not. The alarm is designed to prevent a near miss, not respond to one.
12/07/10 Patrick Smith/Ask The Pilot/Salon

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Categories: Safety Jul 2010