Nov 03, 2006

I nitial probe indicates that Controlled Flight Into Terrain (CFIT) is the reason behind September 23 chopper crash

By KESHAB POUDEL

Although the high-level probe commission, which was constituted to examine the reason behind Shri Airlines helicopter crash on September 23, is yet to present the final report, the initial investigation, as usual, indicated that the CFIT is the main reason behind the chopper crash.

Crashed chopper : Blame it on CFIT

With the opening of Nepalese sky for private airlines, more than three dozen airplanes have crashed causing immense loss of lives and it was the CFIT that caused almost all the accidents. This year alone, two other accidents involving a Yeti Airlines Twin-otter and a helicopter was blamed on CFIT.

Despite the rising the number of accidents, the civil aviation authorities seem to have failed to reduce it. Due to the frequent changes of the government, there are frequent changes in the management of Civil Aviation Authority of Nepal (CAAN) resulting in instability in policy implementation.

According to aviation experts, CFIT is a significant accident categorization, cited as the cause of most aircraft accidents. CFIT results when an airplane suddenly deviates from its normal flight pattern and flies into terrain. A CFIT accident is one in which "an otherwise-serviceable aircraft, under control of the crew, is flown (unintentionally) into terrain, obstacles or water, with no prior awareness on the part of the crew of the impending collision.”

In the last few years, CAAN claimed that it has conducted a number of safety related seminars in the country and conducted the safety audit including checking the airworthiness of aircrafts.

But CFIT is not the result of aircraft’s mechanical failure, and rarely is it the result of the failure of any governmental or regulatory agency but it is the result of human error -- allowing a well-operating aircraft to fly into terrain.

“If CAAN takes strong measures, the number of accidents can be reduced,” said civil aviation expert. In the geographical terrain like that of Nepal , there is a need to take more precautionary measures.

Until recently, the Ground Proximity Warning System ("GPWS"), and the Traffic Collision Alert and Avoidance System ("TCAS"), were two of the most popular avionics devices available to help combat CFIT. Nepal has also made GPWS as a mandatory but it has not made any impact.

According to CAAN website, there are total numbers of 227 civil aircraft, and 15 operating airlines with nine fixed wing and six helicopters.

"Continued vulnerabilities to controlled-flight- into-terrain accidents demonstrate the need for further improvement in this area. New approaches are needed to supplement or replace the current ground proximity warning systems, such that earlier indications and warnings of potential collisions with terrain are provided and nuisance warnings are eliminated,” said the expert.

An aircraft may experience several abnormalities involving equipment malfunction, unexpected adverse weather conditions, and loss of situational awareness by the flight crew. At the time of chopper crash, the weather at the accident side was bad and visibility was poor. As most of the domestic aircraft flies under Visual Flight Rule (VFR), there are certain mandatory instructions to follow like visibility should be 5 kilometers, one thousand feet above the obstacles and ceiling base of the cloud above 1500 feet.

In all past accidents, almost all these universal instructions were violated. Interestingly, no actions have been taken yet. In case of death of crew members, all blames are put on the dead crews.

Human factor include mistakes caused by voluntary acts, failure to act, and other factors associated with actions or inaction. Cause factors associated with aircraft, engines, and systems include deficiencies in the design, manufacture, maintenance, or operation of the aircraft or its systems.

Personnel error (human factors) is the most common cause of both incidents and accidents. CFIT and loss-of-control accidents, which almost by definition involve human factors, account for more than half of all fatal accidents.

Although aircraft system malfunctions are involved in a relatively small fraction of aircraft incidents and accidents, improvements in aircraft systems often improve safety by making aircraft more robust—providing flight crews with more accurate information to improve their situational awareness and reducing the likelihood that a human error will result in an incident or accident.

As Nepal ’s international reputation has already been damaged following the series of accidents, one cannot escape all the time just pointing at the human failure of the CFIT. The CAN must act to prevent future accidents.