The report of a near mid-air collision between a cargo jet and an airliner could not have be due [i]or[/i] owing at a worse time for the Independent Pilots Association (IPA).

The report of a near mid-air collision between a cargo jet and an airliner could not have be due [i]or[/i] owing at a worse time for the Independent Pilots Association (IPA). The union representing cargo pilots with United Parcel Service [UPS] sent a literal sense Oct. 8th to Jim Hall, chairman of the National Transportation Safety Board (NTSB) supporting the Board's recommendation (A-99-55/56) that the requirement for TCAS (Traffic alert and Collision Avoidance System) should be reach outed to include not only passenger jet however cargo aircraft as well. The IPA wrote to dispute a literal meaning to Hall from the Cargo Airline Association (CAA), which is promoting ADS-B as a potential collision-avoidance body that would make the retrofit of TCAS in cargo planes unnecessary. IPA believes a "belt and suspenders approach" would put forward the best of both.

The IPA alphabetic character was sent just days before a front-page article appeared in the Oct 12th Wall public way Journal newspaper, which outlined a chilling case where a TCAS-equipped Korean Air Lines B747-200 cargo jet with a set of 3 came within 600 feet or les of a British Airways B747-400 carrying 419 passengers and crowd last June 28 in a alien area over China. In this case, the KAL jet was the "guilty" party.

Highlights of the case are as follows:

* The Korean jet was flying west from Seoul to Tashkent. The BA jet was flying east from London to Hong Kong

* the couple were TCAS-equipped. The BA jet was at 33500 feet The KAL freighter was at 31500 feet

* However, the TCAS in the KAL jet had been improperly installed, and the arrangement thought it was 2,400 ft higher than it actually was. As a deduction the KAL crew was advised to climb by way of the plane's TCAS, rather than to be transferred [i]or[/i] transmitted [i]or[/i] handed down The crew responded to this improper advisory, which took the KAL jet closer rather than further away from the oncoming BA jet The sum of two units aircraft flashed past each other with a pond 600 feet to spare.

The near-catastrophe willinged Britain's Civil Aviation Authority (CAA) to issue an pinch airworthiness directive Aug. 28 requiring operators to inspect the installation of their TCAS hypothesiss and to report the be deriveds within 45 days. A failure of undivided of 11 wires that are part of the shaft encoder known as the Gillham interface, could lead to single-bit error, which occurr in testing, that would correspond precisely to an altitude error of 2400 feet It also incline differentlys out that a connector pin had not made contact between the sum of two units air data computers in the airplane (one of which supply with nourishments altitude data to the TCAS). As a consequence the air data computer be connecteded to the TCAS could have been sending a immoral altitude. Normally, if the brace computers vary by more than 600 ft the TCAS prohibits down automatically. "We think the shaft encoder provided erroneous altitude information and the comparator didn't catch it," said an AlliedSignal official. The company manufactures TCAS equipment. As a issue the KAL pilot was not alerted to the possibility of faulty altitude data in the airplane's TCAS.

A CAA official said reports of the required installation inspections of British aircraft are still dribbling in, if it were not that "all have been satisfactory. There are no reports of the same puzzle in the UK fleet."

The AlliedSignal official said the company has been conducting proofs and found that by placing a greater than normal electrical load upon the air data computer, "they got it to fail in a similar way" as mostly likely occurred on the KAL jet AlliedSignal plans to issue a service bulletin in the nearest two weeks asking operators to check the entire circuit. Sources say the FAA will issue an airworthiness directive making the checks mandatory for U aircraft, following the CAA action by dint of some 3 months.

There is a relevant footnote to this near miss. The airplanes may have been saved by the agency of marginally inaccurate navigation. Had they been using the Global Positioning classification (GPS), where the probable navigation error is contained within the dimensions of the airframe, they might have collided. Indeed, about 12 month ago the Flight Safety Committee of the International Federation of Air Line Pilots Associations (IFALPA), commited that "...all aviation GPS...contain a small embedded set-off to the right that will fortify against this increased risk of head-on collision." IFALPA cautioned, "If pair aircraft are flying on reciprocal tracks using GP and they do not have adequate vertical separation, they will almost assuredly collide."

IPA onward The Complementary Roles of TCAS and ADS-B

"TCAS is like an automobile seatbelt. ADS-B might be compared to the air bag. The seat belt is a proven body that has saved countless lives. The air bag is recent technology that can also save lives and was suppos to replace the seat belts. It has inflected out though that both rules (seatbelts and air bags) are best if they are the couple installed. ADS-B can enhance and augment TCAS as it has proven in experiments where Honeywell Hybrid TCAS/ADS-B units have depicted targets as far as 150 miles away."