Macedonian King Air accident shows value of TAWS

 - November 1, 2006, 6:49 AM

Analysis of last year’s fatal accident involving a King Air carrying Macedonian president Boris Trajkovski and others reinforces the value of the FAA’s requirements for terrain awareness and warning systems (TAWS) on certain aircraft. Since March 29 all U.S.-registered turbine aircraft more than three years old and configured with more than five seats (excluding flight crew) must be equipped with TAWS or enhanced ground-proximity warning systems (EGPWS) under FAA final rule 4910-13. Such equipment has been mandatory on new aircraft for the past three years.

The February 2004 King Air fatal was one of several recent accidents involving public officials, leading a senior U.S. safety official to call for improved standards of operation. Flights with state-owned aircraft could be made even safer with wider adoption of safety management systems, according to an NTSB investigator with particular knowledge of fatal accidents involving government airplanes.

NTSB chief advisor for international safety affairs and U.S.-accredited representative Robert MacIntosh has analyzed controlled-flight-into-terrain (CFIT) accidents involving the president of Ecuador, U.S. Department of Commerce Secretary Ron Brown, and Trajkovski, saying that the accidents share common issues of safety management.

He extended his safety concerns to other corporate aircraft, air taxis and equipment flown by “mini-airlines.” “Regardless of the ownership of the operation–a state government, a corporation or a small independent operator– the prescription to avoid such events lies in adopting the professional practices of a safety management system,” said MacIntosh.

MacIntosh recounted the circumstances of the Macedonian accident at the Flight Safety Foundation European Aviation Safety Seminar in Warsaw, Poland, in March. Analysis of the Macedonian event using the Flight Safety Foundation approach and landing accident reduction (ALAR) risk-assessment program shows the flight involved a number of factors that often contribute to such events. These factors included an unfamiliar destination, high terrain, a nonprecision approach with stepdown fix, bad weather on arrival and a lack of standard operating procedures covering the flight.

Citing the positive results that the commercial air-transport sector has achieved in reducing CFIT events, MacIntosh called for a greater adherence by operators to the International Business Aviation Council’s International Standard for Business Aircraft Operations. “This type of accident can be avoided with the introduction of concepts that include initial risk assessment, compliance with standard operating procedures, proactive crew resource management programs and mandatory early missed approach,” he said.

Delivered to Macedonia in 1980, the King Air was registered to the Air Transport and Maintenance Department (ATMD). The ATMD, which manages government aircraft, is a semi-autonomous unit of the Directorate General of Civil Aviation (DGCA).

Accident investigators reported that the airplane had flown 6,000 hours and was clear of maintenance discrepancies. The aircraft came equipped with an OEM-installed cockpit voice recorder and a foil-media flight data recorder (despite an International Civil Aviation Organization requirement that use of such equipment be discontinued after December 1994). In 1998 the operator outfitted the airplane with an autopilot coupled to a GPS.

The captain had logged more than 7,000 hours and had flown King Airs since 1979; his ATP license had been revalidated with ground training and King Air flight training in 2000. He worked for the ATMD as required among other jobs, including work for the DGCA.

No Descent Checklist

The copilot, also working under contract, had flown 1,300 hours, including 600 hours on King Airs; his previous ATP check was two months before the accident and his last King Air ground school was in 2000. Macedonia did not require recurrent ground training or formal flight-refresher courses. The ATMD did not have standard operating procedures to specify operational or training requirements, and the local civil aviation authority did not oversee its activities.

The flight plan, which called for overflight clearance from five states, was prepared two days before the flight; it subsequently had to be resubmitted to include a previously omitted navigation fix (barit). A weather briefing on the morning of the flight forecast low ceiling and visibility and deteriorating conditions due to a passing warm front. Neither pilot had flown to Mostar for some 12 years. Upon initial descent following the one-hour flight from Macedonia, the weather at Mostar was given as broken cloud at 1,600 feet, with five miles visibility in light rain. Although the cloud ceiling was below instrument-approach minimums, the crew did not initially discuss it, according to the accident report. In addition to this, the CVR also has revealed no evidence of an approach briefing, or of a descent checklist.

MacIntosh points out that the pilots did not follow the correct Mostar arrival clearance. The King Air crew initiated descent to Mostar’s Runway 34 early while proceeding to the diruk initial approach fix. The CVR transcripts show that the copilot (the pilot flying) had questioned the captain about altitude requirements beyond diruk, as well as about GPS indications. The captain was apparently talking the copilot through the approach chart. There was only one chart visible in the cockpit.
The King Air crew descended prematurely, coming down about five miles short of the runway at Mostar (Bosnia Herzegovina), near a point more than 1,000 feet below the local minimum descent altitude (MDA).

The NTSB investigator used the FSF ALAR checklist, which is designed to assist with risk assessment, to highlight many of the typical CFIT-accident contributing factors that were present in the circumstances surrounding the flight. They included:

• no radar coverage;

• a short sector, with high workload and an unfamiliar destination;

• high terrain, with nonprecision approach with stepdown fix;

• 4.75-degree descent gradient from the final approach fix to the MDA;

• nonscheduled international flight;

• east Euro-Asian destination;

• no operator standard operating procedures for dispatch, flight operations or crew resource management

• weather forecast below minimums at arrival.

The Bosnia Herzegovina aircraft accident investigation commission final report highlights several findings, said MacIntosh. These include the crew’s premature descent; a loss of VOR and DME signals for 18 seconds with no action taken; the captain’s acknowledgment of copilot communications with continued confusion; the pilots had ignored the approach stepdown procedure on their descent to the MDA; the crew continued descent through the MDA (despite an acknowledged 500-foot radio altimeter indication); and the impact occurred at 1,774 feet about five miles from the runway (compared with a 2,910 feet minimum altitude shown on the approach chart at the 4.7-mile point).

The final report recommended that the ATMD introduce a safety management system and that a local civil aviation authority oversee the agency.

MacIntosh emphasized that everyone involved in aviation safety needs to learn the lessons of this accident. “We must recognize the final line of defense– TAWS. The [system’s] visual and audio warnings are vivid, and combined with crew training and discipline we know that TAWS can save airplanes. When you consider the alternative, a possible CFIT accident, TAWS is worth the investment,” he concluded.