US Airways flight, small jet nearly collide in midair

[700UW]

A US Airways flight bound for Charlotte and a small private jet leaving Statesville narrowly missed hitting each other Tuesday morning about 15 miles west of Greensboro, a representative of the air traffic controllers union said.

As US Airways Flight 829 heading southwest from Richmond, Va., was descending at about 7:50 a.m., a controller directed the private jet, heading northeast, to climb above Flight 829's path, said Calvin Phillips of the National Air Traffic Control Association. Phillips works at Atlanta Center, which directs air traffic for much of the Southeast, including Charlotte.

When the small jet's pilot said he couldn't climb that high, the controller tried to direct Flight 829 to hold its altitude, Phillips said. But the US Airways pilot didn't respond for several seconds, Phillips said, and the two planes ended up at about 16,500 feet and about eight-tenths of a mile apart.

Air traffic controllers generally try to keep either five miles or 1,000 feet of altitude between planes, Phillips said. The US Airways pilot ultimately saw the other jet and turned to avoid it, Phillips said.

US Airways spokesman Phil Gee said Flight 829 had 117 passengers and five crew members. The crew continued on to its next flight, Gee said, and US Airways is investigating the incident.

 

[WCT]

A US Airways flight bound for Charlotte and a small private jet leaving Statesville narrowly missed hitting each other Tuesday morning about 15 miles west of Greensboro, a representative of the air traffic controllers union said.

As US Airways Flight 829 heading southwest from Richmond, Va., was descending at about 7:50 a.m., a controller directed the private jet, heading northeast, to climb above Flight 829's path, said Calvin Phillips of the National Air Traffic Control Association. Phillips works at Atlanta Center, which directs air traffic for much of the Southeast, including Charlotte.

When the small jet's pilot said he couldn't climb that high, the controller tried to direct Flight 829 to hold its altitude, Phillips said. But the US Airways pilot didn't respond for several seconds, Phillips said, and the two planes ended up at about 16,500 feet and about eight-tenths of a mile apart.

Air traffic controllers generally try to keep either five miles or 1,000 feet of altitude between planes, Phillips said. The US Airways pilot ultimately saw the other jet and turned to avoid it, Phillips said.

US Airways spokesman Phil Gee said Flight 829 had 117 passengers and five crew members. The crew continued on to its next flight, Gee said, and US Airways is investigating the incident.

Just goes to show we have some execellent pilots on both sides, still keeping us all safe. Thank You!

 

[flyin2low]

And TCAS

 

[CynicalResAgent]

not to go off topic (but for the record, good job on the crews part for avoiding the aircraft). How does the TCAS work? Does TCAS only alert the pilots of another approaching aircraft with TCAS equipment installed? I am thinking specifically about smaller general aviation aircraft. Is it a specific system installed to detect other aircraft equiped the same or does it just detect another aircrafts transponder signal? I've flown around in 172's and I'm just curious how that works.

 

[700UW]

TCAS involves communication between all aircraft equipped with an appropriate transponder. Each TCAS-equipped aircraft "interrogates" all other aircraft in a determined range about their position (via the 1030 MHz radio frequency), and all other craft reply to other interrogations (via 1090 MHz). This interrogation-and-response cycle may occur several times per second.

Through this constant back-and-forth communication, the TCAS system builds a three dimensional map of aircraft in the airspace, incorporating their bearing, altitude and range. Then, by extrapolating current range and altitude difference to anticipated future values, it determines if a potential collision threat exists.

It should be noted that TCAS and its variants are only able to interact with aircraft that have a correctly operating transponder.

The next step beyond identifying potential collisions is automatically negotiating a mutual avoidance maneuver between the two (or more) conflicting aircraft. These avoidance maneuvers are communicated to the flight crew by a cockpit display and by synthesized voice instructions.

Automatic Dependent Surveillance-Broadcast (ADS-B) messages are transmitted from aircraft equipped with suitable transponders, containing information such as identity, location, and velocity. The signals are broadcast on the 1090 MHz radio frequency. ADS-B messages are also carried on a Universal Access Transceiver (UAT) in the 900 MHz band.

TCAS equipment which is capable of processing ADS-B messages may use this information to enhance the performance of TCAS, using techniques known as "hybrid surveillance". As currently implemented, hybrid surveillance uses reception of ADS-B messages from an aircraft to reduce the rate at which the TCAS equipment interrogates that aircraft. This reduction in interrogations reduces the use of the 1030/1090 MHz radio channel, and will over time extend the operationally useful life of TCAS technology. The ADS-B messages will also allow low cost (for aircraft) technology to provide real time traffic in the cockpit for small aircraft. Currently UAT based traffic uplinks are provided in Alaska and in regions of the East coast.

Hybrid surveillance does not include the use any of the aircraft flight information in the TCAS conflict detection algorithms; ADS-B is used only to identify aircraft that can safely be interrogated at a lower rate.

In the future, prediction capabilities may be improved by using the state vector information present in ADS-B messages. Also, since ADS-B messages can be received at greater range than TCAS normally operates, aircraft can be acquired earlier by the TCAS tracking algorithms.

The identity information present in ADS-B messages can be used to label other aircraft on the cockpit display (where present), improving situational awareness.