Diyarbakir Plane Crash [Turkish Airlines Flight 634]

Diyarbakir plane crash is one of the biggest air crash of Turkish aviation history…

“Once again, the problem was lack of ILS”
Sabah Newspaper, January 10th, 2003

In order to form a more economical cost model, Turkish Airlines founded the sub-brand Türk Hava Taşımacılığı (THT – Turkish Air Transport) in 1989. THT resembled Anadolujet, another affiliate of Turkish Airlines which has been very successful since its foundation in 2008. Based in Ankara, THT organized domestic flights. However, the THT project did not last long. The company, which was founded in 1989, was closed in 1993.

The company, of which all personnel and operations were taken over by Turkish Airlines, had 4 British Aerospace ATP turboprop planes in its fleet. After the company was closed, these airplanes were returned and 4 British Aerospace RJ-70s and 9 RJ-100s were rented in their place. The RJs were to be used mostly for Turkish Airlines domestic flights. These planes, which qualified as regional jets, could carry out landings and takeoffs on short runways. Furthermore, their passenger capacity which varied between 70 and 100 made it possible to implement a more flexible tariff structure.

The replacement of the British Aerospace ATPs in the fleet with RJs which were rented from the same company for a long term was criticized by Cem Kozlu who worked as a senior executive in Turkish Airlines for many years. In the book Bulutların Üstüne Tırmanırken (While Climbing Over the Clouds) Kozlu wrote to recite the story of the transformation he started in Turkish Airlines, it is stated that an extensive feasibility study was not carried out for the process of exchanging ATPs with RJs and that the report prepared for the process specified that there was a problem in the engines of ATPs. However, Cem Kozlu’s book also stated that the RJs with four engines had more frequent engine problems and in fact, changed engines almost once a month.

I believe that most of you will remember the famous camel sacrifice on the apron of Atatürk Airport. In December 2006, a camel was sacrificed on the apron of Atatürk Airport in order to celebrate the return of the last RJ to Aerospace after its rental period was over. The idea belonged to Airplane Maintenance Director Şükrü Can. Bringing and sacrificing a camel in an airport, which is a place of high strategic importance and heavy security measures, was received by the public with bewilderment and criticism. In fact, the news piece by Reuters which compiled the “strange events of 2006” began with this incident.

The adventure of Turkish Airlines with the RJs lasted 13 years. The fact that the return of the planes caused officials to celebrate by sacrificing a camel was the evidence of how little they were loved by maintenance workers, as well as passengers. In any case, these planes had a pretty depressing history of accidents and incidents in Turkish aviation.

On January 11th of 1998, the RJ-100 with the registration code TC-THF and the name “Şanlıurfa” drifted off the airfield after landing at the end of its flight between Istanbul and Samsun. In this first serious incident involving a RJ, the 68 passengers and 6 crew members on board survived without any injuries. After making a failed attempt to land in the 21 numbered end of runway 03/21 in Çarşamba Airport of Samsun, the plane went around and attempted a second landing on the 03 numbered end. Despite succeeding to land this time, the plane could not slow down soon enough and drifted off the airfield for 150 meters. After the incident, “Şanlıurfa” was taken out of service.

On April 22nd of 2000, a similar incident occurred in Siirt. The RJ-70 with the registration code TC-THL and the name “Kahramanmaraş”, which was about to end its flight between Ankara and Siirt, failed to stop on the runway and slid off the airfield. The 42 passengers and 4 crew members on board survived.

On January 8th in 2003, on the other hand, an RJ-100 of Turkish Airlines with the registration code TC-THG was involved in a fatal crash. The tragic accident which occurred during the last stage of flight no. TK634 between Istanbul and Diyarbakır claimed the lives of 75 people.

The RJ-100 “Konya”, which took off from Atatürk Airport in Istanbul at 06:43 PM on January 8th in 2003, had 75 passengers and 5 crew members on board. The plane was flown by Chief Pilot Alaaddin Yunak and Co-Pilot İsmail Altuğ Ulusu. Weather conditions had become very bad when “Konya” started preparations to land in Diyarbakır Airport. Visibility was very low due to heavy fog. Diyarbakır Airport, which was a military airfield, lacked the instrument landing systems (ILS) which allowed planes to land safely under low visibility conditions. In other words, the pilots could only land the plane by relying on visuals but their view of the airfield was hindered by the fog.

In such cases a lower limit of altitude, below which planes should not descend, is specified to facilitate landing. This limit value, which is referred to as Minimum Descent Altitude (MDA), was designated as 2800 feet for Diyarbakır Airport. The pilots had to cancel the landing and go around if they still didn’t get a reliable visual of the airfield after descending to the MDA. “Konya” approached runway 34 of Diyarbakır Airport and descended to 2800 feet. However, the pilots were still unable to see the airfield. In spite of this fact, “Konya” descended below the MDA and crashed into a hill with a grade of 10% while travelling at a speed of 243 km/h at 08:18 PM according to local time. A fire broke out in the plane after it broke into three pieces during the crash that occurred 900 meters away from the runway. 75 of the 80 people on board died. 5 passengers managed to survive with injuries.

The part of the final investigation report with the title “Meteorological Information” included a striking paragraph which explained how limited visibility was due to the heavy fog:

“The officers on patrol and fixed post guard duty near the site where the plane crashed at the time, as well as the military rescue personnel that arrived at the location right after the crash, stated that the weather was dark and extremely foggy, the range of visibility got as low as 1 meter at places and that even the light of the fire that broke out could not be seen until they got really close to the wreckage.”

In other words, one couldn’t see beyond one’s nose that evening…

Alaaddin Yunak, chief pilot of “Konya”, had started flying in the Turkish Air Force in 1990. Yunak, who flew F-104s and F-5s in the Turkish Air Force, had spent time on duty in the 8th Main Jet Base Command in Diyarbakır Airport before resigning from the military. He began training for Boeing 737s in Turkish Airlines on December 11th in 1995 and worked as a co-pilot in these planes at first. On February 26th in 2002, Yunak began orientation and chief piloting training on RJ-70s and RJ-100s. 401 hours of the 6.309 hours of flight time logged by Yunak throughout his career had been spent in RJ-70s and RJ-100s.

Co-Pilot İsmail Altuğ Ulusu had graduated from the Civil Aviation School of Higher Education in Anadolu University. Ulusu received his Instrument Flight Certificate and Commercial Pilot License, which also authorized him to fly RJ-70s and RJ-100s, on April 25th of 2000. By the time of the crash, he had logged a total flight time of 2.052 hours, of which 1.802 had been spent in RJ-70s and RJ-100s.

The part of the final investigation report with the title “Personnel Information” stated that the cockpit crew consisted of a chief pilot with little experience in RJ-70s and RJ-100s and a co-pilot who had more experience with these planes.

Turkish Airlines gave flight training for RJ-70s and RJ-100s in its training facilities situated within Atatürk Airport. The RJ-100 operations of Turkish Airlines were carried out in accordance with the Operations Manual and Standard Operating Procedures of the Civil Aviation General Directorate. In the manual, the procedure regarding non-precision landing minima was described as given below:

“Pilots will not continue approach to an airfield over which they will descend below the MDA (Minimum Descent Altitude) unless they see and recognize at least one of the visual references below:

– Elements of the approach lighting system
– Threshold
– Threshold markings
– Threshold identification lights
– Visual “glide slope” indicator
– Landing zone or landing zone markings
– Landing zone lights
– Airfield edge lights
– Other visual references accepted by relevant authorities

As clearly indicated in the manual, visual elements are very important during non-precision landings, which are landings carried out without instrument systems.

On January 8th of 2003, both pilots explicitly stated that they could not see the runway due to fog even while approaching at the 2800-feet MDA; in spite of this, the chief pilot issued an instruction to “continue on to 500 feet” and the instruction was confirmed by the co-pilot. At that point, the pilots breached standard approach procedures and lowered the plane below the MDS despite being unable to get a visual. The Ground Proximity Warning System (GPWS) which was mentioned in the previous sections of the book became active as usual and gave the necessary warning to the pilots. However, the information in the final investigation report indicate that the pilots did not respond properly to the warning from the system.

It is stated in the conclusion part of the final investigation report that the cockpit crew insisted on landing in spite of not being able to see approach lights or the runway at the 2800-feet MDA and that the adverse weather conditions were also one of the factors affecting the reason behind the crash.

After the accident, the safety of the airports in the east once again became a topic of discussion. Diyarbakır Airport was a military airfield and it lacked an ILS. The 10 January 2003 dated issue of Sabah Newspaper touched upon the subject with the headline “Once again, the problem was lack of ILS”.

The words “once again” in the headline were very meaningful. The details of the news piece reminded readers of the accident in Van in the year 1994. In the Van incident of 1994, a plane had crashed while attempting to land under conditions of low visibility in an airfield which lacked an ILS system. This accident, too, had occurred due to the insistence of the chief-pilot to land. In fact, there were many fundamental similarities between the Van incident of 1994 and the Diyarbakır incident of 2003.

The same news piece also included a claim that the military had objected to an ILS in the airport. After the Van accident, Turkish Airlines requested for an ILS to be installed in Diyarbakır Military Airfield, which it used for civil transport. The project was discussed during an assembly of the board consisting of representatives from State Airports Administration (DHMİ), General Directorate of Civil Aviation, Turkish National Police and Turkish Air Force. It was alleged that the military representatives objected to installation of the system due to security purposes. The representatives noted that the airfield was being used for military purposes and stated that such a system would hinder the low altitude flights of military planes, as well as a landing type with a safety net, referred to as “latching”. According to the claim in the news piece, the installation of an ILS was suspended due to objection from the Air Force. Mehmet Karakan, who was the deputy director general of DHMİ at the time, confirmed the allegation with the remark, “As you know, Diyarbakır Airport is operated by the military. The installation of an ILS in the airport was discussed but the military objected to it due to security reasons”.

The issue of Sabah which was published the next day, however, had a news piece with the title “Military response on the subject of ILS”. According to the said news piece which was published on January 11th in 2003, the Turkish General Staff reacted very strongly to the claim that the military had prevented the installation of an ILS. An explanation by a high ranking officer was also quoted in the paper:

“Civil aviation operators requested that we share our airfield with them by stating that building new airports would incur additional expenses. We put suitable military airfields to their use. Diyarbakır Airport was one of these. However, we have never received any applications for implementation of ILS in it. In any case, ILS equipment is readily used in both İncirlik Air Base and Yeşilköy Atatürk Airport. Why not in Diyarbakır as well?

Previously, it was suggested for an ILS system with long antennas to be used. Back then, the suggestion was protested since the antennas hindered the landing and takeoff of planes; however, this is not an issue now because there is no antenna ILS equipment left anymore. The only reason we don’t use it ourselves is that we already have our own system for military planes.”

In Van, where it was very common for the range of visibility to decrease due to bad weather in winter, a plane crashed in 1994. The airfield where the plane was trying to land in had no ILS. The pilot insisted on attempting to land despite not being able to see the runway. 54 people died.

Years passed.

In Diyarbakır, where it was very common for the range of visibility to decrease due to bad weather in winter, a plane crashed in 2003. The airfield where the plane was trying to land in had no ILS. The pilot insisted on attempting to land despite not being able to see the runway. 75 people died.

After these two incidents, between which the similarities were heartbreakingly high, the reasons behind the lack of the required infrastructure started to be questioned. Civil authorities claimed that the military had interfered while the military denied having interfered. In any case, planes continued to land in Diyarbakır by having to rely solely on visuals during the 5 years that followed the crash. Eventually, in March 2008, an ILS was installed in Diyarbakır Airport.

For some years, commemorative ceremonies were held on the anniversary of the crash. However, these were performed in the terminal of Diyarbakır Airport instead of being conducted at a monument at the crash site. Hopefully, such a monument will be built on the site in memory of all those who were lost in the accident in 2003 and we will meet at it on the 8th of January every year.

Some other notable details on the accident are:
– Currently, the most fatal incident involving an Avro RJ-70 or RJ-100 is the accident in Diyarbakır.
– RJs were planes known for their safety. At the time of the crash, the Queen of England was also using an RJ.
– At the time, the Diyarbakırspor coach, team captain and goalkeeper were saved from probable death by missing the flight.
– The site where the plane crashed is within the zone reserved for the 2nd Tactical Air Force Command.
– There were three babies among those who died.
– Years before the crash, on February 23rd of 1998, an RJ-100 with the registration code of TC-THE was hijacked during a flight between Ankara and
Adana, and forced to land in Diyarbakır Airport. The hijacker Mehmet Dağ had passed a toy panda as being fitted with a bomb and demanded for the plane, which had 63 passengers on board, to go to Tehran. After the plane landed in Diyarbakır Airport for refueling, the hijacker was neutralized before he had a chance to hurt anybody.



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