Plane & Pilot
Tuesday, September 6, 2011

When Airplanes Collide: Avoiding The Unexpected


With midair collisions showing no sign of decreasing, “See and Avoid” is more important than ever


The newest development in TCAS is Automatic Dependent Surveillance-Broadcast (ADS-B). With ADS-B, aircraft (or obstacles) will broadcast a message on a regular basis, which includes their position (latitude, longitude and altitude), speed and other information. Receiving equipment in aircraft will acquire this information for use in a several applications, including TCAS.

Instead of today’s systems that must constantly scan for a conflicting aircraft’s position, ADS-B systems will simply receive the accurate position report from the broadcasting aircraft.

The problem with TCAS is that for it to be completely effective, all of the aircraft in the airspace must be equipped with altitude-encoding transponders, which must also be accurate.

Max Trescott, who’s a recognized industry expert on glass cockpits and is the 2008 National CFI of the Year, says this about TCAS: “The big gotcha in these systems is that the altitudes are based on transponder output from both aircraft. But since either aircraft’s transponder could be off as much as 200 feet and still be legal, there could be as much as a 400-foot discrepancy in the relative altitudes displayed. Whenever a conflicting target is within 500 feet of their aircraft, pilots should locate the traffic or change altitude to increase the separation. Don’t be complacent just because the TCAS shows they’re 500 feet above or below you.”

Use Every Tool

It’s clear that though technology continues to evolve in the cockpit, a combination of visual methods along with TCAS should be used in avoiding midair collisions. Since traffic avoidance is our prime responsibility, we need to take it seriously and practice using every tool at our disposal.

It’s noteworthy that there has been no midair collision involving an air-carrier aircraft in the past decade, and that may be an indicator that TCAS is doing its job in increasing traffic awareness. Still, we have to be careful not to rely only on technology to keep us safe. After all, the only place we should be meeting other pilots face-to-face is on the ground, after the flight.

New “See And Avoid” Safety Portal

The FAA feels that midair collisions are enough of a problem that it’s now hosting the See and Avoid website on FAASafety.gov. The portal (www.seeandavoid.org) was originally developed by the Air National Guard Safety Division, though it now includes data from all branches of the military.

The purpose of the safety portal is to eliminate midair collisions and reduce close calls through continuous flight safety and proper flight planning. The portal provides civilian and military pilots with reciprocal information and education on airspace, visual identification, aircraft performance and mutual hazards to safe flight.

See and Avoid is targeted at two groups—the first is general aviation pilots, who are encouraged to include SeeAndAvoid.org as part of their flight planning. Since most GA pilots use the Internet to get weather, NOTAMs and flight-planning information already, the FAA feels that knowing where military operations are being done and where military aircraft will be is additional, helpful information so pilots can avoid that airspace. The second targeted groups are military safety officers at the nation’s flying military bases. It allows them to create content to allow civilian pilots to avoid conflicting military operations.

The SeeandAvoid.org interface is easy to use, and includes Google maps with point-and-click interaction. Because the system interfaces with military systems in the continental United States (CONUS), Alaska, Hawaii, Virgin Islands, Guam and Puerto Rico, it gives an instant picture of military operations that civilian pilots want to know about for midair collision avoidance. Note that not all military activity may be displayed, so the FAA still urges caution when flying in areas where military aircraft could be.

Pilots can access the wealth of information available on the portal by visiting www.faasafety.gov or by going directly to the portal at www.seeandavoid.org.





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