Mandala Airlines Flight 091

Mandala Airlines Flight 091

PK-RIM, the aircraft involved in the crash.
Accident summary
Date	5 September 2005 (2005-09-05)
Summary	Pilot error (failure to set flaps/slats properly)
Site	Medan, Indonesia
Passengers	112
Crew	5
Injuries (non-fatal)	41 (including 26 on ground)
Fatalities	149 (including 49 on ground)
Survivors	17
Aircraft type	Boeing 737-230 Adv
Operator	Mandala Airlines
Registration	PK-RIM
Flight origin	Polonia International Airport Medan, Indonesia
1st stopover	Soekarno-Hatta Int'l Airport Jakarta, Indonesia
2nd stopover	Adisumarmo International Airport Surakarta, Indonesia
3rd stopover	Adisucipto International Airport Yogyakarta, Indonesia
Last stopover	Juanda International Airport Surabaya, Indonesia
Destination	Ngurah Rai International Airport Denpasar, Indonesia

Mandala Airlines Flight 091 was a scheduled domestic passenger flight that originated from Polonia International Airport in Medan, Indonesia to Ngurah Rai International Airport in Denpasar via 4 Airports in Indonesia. On 5 September 2005 (10:15 a.m. UTC+7), the flight crashed into a heavily populated residential area seconds after taking off in Medan. There were 149 fatalities.

Dozens of houses and cars were destroyed, and 49 people perished on the ground. 17 passengers survived the accident, with 100 of those on board known to have died. Most of the survivors are thought to have been seated at the rear of the aircraft, though some have reportedly since died from their injuries. Most of the dead were Indonesian, although at least one Malaysian, Ti Teow Chuan from Sabah, was reported dead. Rizal Nurdin, the governor of North Sumatra at the time, and Raja Inal Siregar, the former governor, were among the dead.

Flight 091 is currently the third-deadliest aviation accident in Indonesia, after Garuda Indonesia Flight 152 and Indonesia AirAsia Flight 8501. It was also the second deadliest air disaster in North Sumatra province, the deadliest civilian plane crash in Medan, and the deadliest airplane crash since the loss of West Caribbean Airways Flight 708 earlier that year. Consequently, it was also the deadliest air disaster involving the Boeing 737-230 Advance.

Passengers

All passengers are Indonesian. All five crew members, 95 of the 112 passengers, and 49 people on the ground were killed. 15 of the 17 surviving passengers were injured. Twenty-six people on the ground were seriously injured in the accident

Survivors

A passenger named Rohadi Sitepu told Metro TV from hospital that he and five other people seated in the back of the plane in Row 20 had all survived. "There was the sound of an explosion in the front and there was fire and then the aircraft fell," he said. Rohadi said he escaped the blazing wreck by jumping through the torn fuselage and fleeing on foot as four large explosions erupted behind him.

Another survivor, Freddy Ismail, told Elshinta Radio from his hospital bed that the aircraft seemed to be experiencing mechanical difficulties after take-off. "After take-off, the noise of the engine suddenly became very loud and the aircraft began shaking intensely before it suddenly fell," he said. Among the passengers were:

• Rizal Nurdin
• Raja Inal Siregar

Aircraft and airline

The plane involved in the accident while operating with Lufthansa registered D-ABHK.

The aircraft, Boeing 737-230 Adv registration PK-RIM, was built in 1981 and formerly belonged to Lufthansa where it was registered as D-ABHK "Bayreuth" and was acquired by Mandala in 1994. The aircraft was 24 years old by the time of the accident. It had a Certificate of Airworthiness valid until November 2005.

Mandala Airlines was established in 1969 and is one of several low-cost airlines that serve the vast Indonesian archipelago. At the time of the accident it was 90-percent owned by a foundation set up by the Indonesian Army strategic reserve Kostrad (Komando Strategis Angkatan Darat). In 2006 it was acquired by Cardig International and Indigo Partners. It has 1,000 employees (at March 2007).

Accident

Flight 91 departing for Soekarno-Hatta Airport, Jakarta from Medan. The previous flight was from Jakarta and arrived at Medan uneventfully. The same crew have flight schedule on the same day and returned to Jakarta. The flight was a regular scheduled passenger flight and was attempted to take-off from Polonia Airport, Medan, North Sumatera to Jakarta and it was the second trip of the day for the crew.

At 10.02 WIB, Flight 91 received clearance for take off with additional clearance from ATC to turn left heading 120 and maintain 1500 ft. The crew read back the clearance heading 120 and maintains 1000 ft. The ATC corrected the clearance one thousand five hundred feet. The crew re- read back as 1500 ft. The plane later took-off. Some of the passengers and other witnesses stated that the aircraft has lifted its nose in an up attitude and take off roll was longer than that normally made by similar airplanes. Most of them stated that the aircraft nose began to lift-off about few meters from the end of the runway. The ATC tower controller recalled that after rotation the plane began to “roll” or veer to the left and to the right. Eyewitnesses on the ground also reporting the same. Witnesses stated that the plane shook violently (possibly indicating a stall). The airplane then overran the departure end of Runway 23, impacted several approach lights, traveled through a grass area and over a river. Some witnesses on the ground recalled that the airplane left wing struck a building before it struck in the busy road, then heard two big explosions and saw the flames. As the airplane came to rest, it fractured into three parts. The airplane is considered total loss due to the impact forces and post-crash fire. The aircraft had been separated due to impact along the flight track beginning from the end of the runway 23, and then the aircraft stopped into a halt 540 m from the end of runway. Most of the fuselage section was destroyed by post-impact fire. The remaining part of the fuselage is only the tail section. Both engines have detached from the aircraft due to impact to the ground. The right engine was found about 300 m and the left engine about 400 m from the end of the runway 23.

Rescue Operation

At 10.25 AM local time, the ATC declared the airport closed. The airport fire brigade immediately responded to the crash bell activated by the ATC. When they arrived at the end of runway 23 they realized that the crash site was outside the airport perimeter, and there is no access road to reach the accident site. When they arrived, the fire was still burning at the crash site. Several fire fighting units of the local government and ambulances participated in rescue operation. The local people, Police and others were involved in the first hour of the rescue, and later on the Indonesian Air Force and Army. Some victims were evacuated using commercial as well as private cars; it was due to late arrival of the ambulances to the crash side and their limited number.

At the crash site, there was no person in charge as the coordinator among the rescue teams. The overly crowded situation caused difficulties to the rescue teams in evacuating the victims. According to the witnesses, there was no label to the victims and no triage area set-up as mentioned in the AEP. Moreover, the rescue team did not know where the uninjured passengers should be transferred to the collection area. The records/ labels and the location of the victims were not well documented. The local people tried to rescue one of the pilots; however they were unable to release the pilot from his harness. It is because they were not familiar with aircraft components. While they were trying to save the pilot, suddenly the fire blast came from behind. When they saw the fire, they ran away to avoid the flame. According to them, one of the pilots was still alive at the time they found him. However after the fire was extinguished, the pilot’s body was not found. The pilot seat was totally burnt. A person who stood close to a store saw that the fire started a few minutes after the aircraft crashed. He could not recall the exact time of the crash. He tried to rescue one of the victims to avoid the fire. According to other witnesses, the fire started a few minutes after the crash.

Investigation

The FDR and The CVR was found and sent to Washington to be read out by the NTSB in USA. It found in a good condition; however, the team experienced difficulty reading the Cockpit Area Microphone (CAM). The team also found that the channel from the CAM was masked by hum and noise dominating the signal. There are some voices heard on the CAM track, there are numbers of step changes in background noise level and character that may be consistent with an intermittent electrical connection in the CAM wiring circuit. As a result, the team was not able to conclude that the CAM was providing input to the CVR throughout the entire 30 minutes. Such a poor quality in CVR record failure makes it impossible to find out whether the flight crews made proper take-off configuration procedures including checklist execution. However several crew words, cockpit switch activations, engine noise, and cabin chime sounds heard on the CAM channel of the CVR are typically at a volume level much lower than the standard take off warning horn of the Boeing 737-200. The typical sound of the take-off configuration warning was not heard in the CVR CAM channel. The stick-shaker warning (typically as loud as or louder than the takeoff warning horn) was also not heard on the CVR CAM channel.

The disassembly examination of both engines revealed there was no defect with the engines that contributed to the accident. Observers reported smelling durian fruit in the crash, leading to suggestions that the plane was overloaded with the prized fruit. The director of the airline initially denied that durian was on board, but later admitted that 2.7 tonnes were loaded. The NTSC confirmed that 2 tonnes of durian were on board. However, weight and balance examination also revealed that the actual aircraft take-off weight and center of gravity met the requirements and standards take-off performance. The weather itself was not a factor on this accident.

The official final report on the accident was released by the National Transportation Safety Committee (NTSC) of Indonesia on 1 January 2009. According to it the probable causes of the accident were the following:

• The aircraft took off with improper take-off configuration, namely with retracted flaps and slats causing the aircraft failed (sic) to lift off.
• Improper checklist procedure execution had led to failure to identify the flap in retract position.
• The aircraft's Take-off warning system horn was not heard on the CAM channel of the CVR. It is possible that the take-off configuration warning was not sounding.

Similar incidents

Other accidents where the aircraft crashed shortly after takeoff, due to improper settings of flaps or slats, with parallel failure of the takeoff misconfiguration warning horn system, include Delta Air Lines Flight 1141, Spanair Flight 5022, Northwest Airlines Flight 255, and Lufthansa Flight 540.

See Also

• List of aircraft accidents and incidents resulting in at least 50 fatalities
• List of accidents and incidents involving commercial aircraft

References

This article incorporates text from this source, which is in the public domain: Aircraft accident report

External links

• Final Report (Archive) – National Transportation Safety Committee
• Accident description at the Aviation Safety Network
• Accident description on planecrashinfo
• Photograph of the wreckage PK-RIM. From Airliners.net. Retrieved 2010-01-23.