National 6 (Spotlight Weekly)

CFIT Again

Another tragedy underscores the urgency of firm action against Control Flight Into Terrain accidents

By KESHAB POUDEL

Despite aviation authorities' order to improve airlines' navigational systems, Nepal has been witnessing a couple of crashes of a similar nature. Just a month after a Twin Otter belonging to Skyline Airline crashed at Surkhet, a similar aircraft belonging to Shangri-La Airways crashed at Pokhara valley, killing all 18 passengers, including 13 Germans, one American, one Briton, and three crew members.

Cabin crew : III fated

The plane was flying at 3.700 feet at the time of the accident and was approaching the airport. The aircraft pilots could have seen the apron in good weather . Unfortunately, Captain Bipin Mishra seemed to have descended without being aware of the height and hit the mountain.

In similar weather conditions, Skyline Airline's aircraft hit a nearby mountain just a few minutes before approaching Surkhet Airport. In both cases, the airplanes were under total control of the captains with primary navigation system like Global Positioning System (GPS). In a country like Nepal, a modern Terrain Awareness Warning System (TAWS) is needed to prevent Control Flight Into Terrain (CFIT) accidents. Accurate navigation information is crucial to descent or departure in mountainous areas. GPS is
now widely used to back up conventional navigational aids.

As new navigation systems like Enhanced Global Proximity Warning System (EGPWS) are available, the country should use them in airlines. EGPWS shows the terrain, highlights the tallest mountains, and indicates the height of the lowest and height terrain in the display. According to experts, EGPWS helps during a descent into airport surrounded by high terrain.

Although all airplanes are using the GPS, a navigational equipment which explains the distance and track of the aircraft, the accidents occurred when pilots failed to follow the equipment while flying in Visual Flight Rules (VFR). Aircraft flying in VFR must avoid fog and clouds and must not fly Instrument Fly Rule (IFR).

CFIT was a term coined in the late 1970s by engineers at Boeing. A CFIT accident is one where an airworthy aircraft in complete control of the pilot has been flown into terrain (ground), obstacles, or water, off the runway with no or little awareness by the pilots, until too late. A CFIT accident is often a sub-classification of approach and landing accidents, but includes all phases of departure climb, curies, and all initial descent.

When Twin Otters and similar aircraft fly on the basis of see-and-see (FVR), the pilot should maintain a safe height till the weather improves. Once the aircraft flies under the guidance of GPS, it must fly completely under the VFR and Visual Meteorological Condition (VMC). The rule is that once the aircraft flying under the VFR rules enter the clouds or fogs, it must apply GPS and maintain a safe height.

Whether in the case of Surkhet, Lukla or Pokhara, the plane was diverted from the regular route and pilots seemed to have descended without knowing its position. Had the Shangri-La aircraft followed the route and height, it would not have hit the mountain at the time of approaching the airport. "The place where the accident took place by no means falls in the air route between Jomsom-Pokhara," said a Pokhara airport official.

When the plane was on en route to Pokhara, the weather was favorable and visibility was good. Four minutes before the crash, another Twin Otter of the same airline and a Cosmic Air flight landed safely at the airport. The Shangri-La Airways-owned Twin Otter was returning from Jomsom, north-west of Pokhara and 200 west of Kathmandu, at 10 am, two minutes before its schedule time of landing.

Flying to places like Jomsom is not easy. The airplane has to pass through a deep gorge to reach Jomsom airport amid hostile wind. The plane prepares for landing passing the most difficult areas. The flight time is normally 18 minutes and in adverse condition s, it is extended up to 20 minutes. On aircraft flying from Jomsom to Pokhara, the captain gets weather briefing from Pokhara Tower before take off. Once the aircraft comes to Tuchhe valley, it gets another weather briefing. Although Captain Mishra, 54, was a veteran pilot, his performance was said to be not good during his career with Royal Nepal Airlines and other private airlines. "The accidents site which is very close to the airport, showed the nervousness on the part of commander," said a civil aviation expert.

According to the Air Traffic Controller Office at the Pokhara, the sudden formation of local cloud and fog, which is a usual pre- and post-monsoon phenomenon, created poor visibility. The government has formed a commission to probe the reasons of the crash.

The nature of the accident indicated that the ill-fated plane hit the mountain when pilot underestimated the height of terrain while descending from the fog and cloud in the approaching zone. The expert argued that the aircraft lost its regular position when it descended keeping in the mind the regular route.

Experts argue that introducing safe systems alone is not adequate in the difficult geographical terrain and weather pattern of Nepal. Unless pilots are made aware about handling procedures and the importance of safety, nothing can prevent accidents. In the past, most of the accidents took place in Nepal because pilots' miscalculation while reading the aircraft's position and height. Had the pilots cited GPS and other navigational system to identify the location, many accidents could have been averted. The problem seems to lie not in the equipment, but awareness of crewmembers.

Civil aviation authority, private airlines operators and pilot union have agreed on a common safety agenda and have targeted CFIT accidents as a top priority. The plan introduced in 2000 by then Director-General of Civil Aviation Authority (CAAN) Nagendra Ghimire aimed at reducing the accident rates to zero percent in the following year.

As per the recommendation of the International Civil Aviation Organization, the CAAN also made efforts to equip Nepalese carriers with an enhanced version of the Ground Proximity Warning Systems, which can substantially increase warning time. According to a civil aviation expert, CFIT accident in Nepal can be reduced by almost 100 percent by installing the system like EGPWS or Terrain Avoidance Warning System (TAWS). Such equipment give sufficient information to the pilots to avert collisions.

CFIT and loss of control accidents are the biggest aviation killers worldwide. Flight International, an international magazine, reported that CFIT accidents killed a large number of people in the world. Following the growing number of accidents, ICAO has shown serious concern on reducing the CFIT accidents. Under ICAO's CFIT working group's recommendation, ICAO amended Annex 6 to require the installation of TAWS, formally known as GPWS, in 2000.

Aircraft manufactured after December 31, 2000 must include an approved TAWS. According to ICAO's guidelines, aircraft with 50 or fewer passenger seats or class B need to install TAWS. It recommends specifically that no person may operate a turbine-powered airplane configured with 10 or more passenger seats excluding any pilot seat, unless that airplane is equipped with any approved TAWS that meets the requirement for class b equipment in Technical Standard Order. Such airplane must also include an approved terrain situational awareness display.

According to the ICAO Annex 6 rule, the airplane flight manual shall contain appropriate procedures for the use of TAWS and proper flight crew reaction in response to audio and visual warning. Nepal, too, issued the airlines operators that the aircraft must include navigational equipment GPWS and other required navigational equipment as per the rule of ICAO but many aircraft are yet to have such equipment.

As CAAN's management was changed frequently under the pressure of ministers, professional employees were sidelined. Despite the availability of the senior and professional staff at the CAAN's head office, acting general manager manages the Tribhuvan International Airport for the last two years.

"One cannot expect change as long as the aviation management is run by non-professionals," said a senior official at the Ministry of Culture and Civil Aviation. "If we go through the system, there are many compromises with private air operators.

Apart from efficient and professional management in CAAN, a high level of awareness in the pilots is also required. Unfortunately, policymakers ignore professionals and appoint their own henchmen in crucial decision-making positions.

"We have been following direction and regulations of the ICAO," said an official with the Aircraft Safety Division at the ministry. "Our airports are as safe as all other airports around the world. We always follow the minimum requirement of the ICAO for VFR."

The cases in the last few years showed that turboprop-powered transport having more than 15 seats crashed during approach and landing. The time has come to evaluate our aircraft security system and to check the efficacy of our navigational system.