Adapted from the Final Crash Investigation Report of 2012 May 9 Sukhoi Superjet-100 plane crash submitted by Indonesian Investigation age...
Adapted from the Final Crash Investigation Report of 2012 May 9 Sukhoi Superjet-100 plane crash submitted by Indonesian Investigation agency NTSC.
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| Sukhoi Superjet |
SYNOPSIS
On board the flight were two pilots, one navigator, one test flight engineer, and 41 passengers.The passengers consisted of 4 Sukhoi Civil Aircraft Company (SCAC) personnel, one engine manufacturer (SNECMA) personnel, and 36 invited passengers (including one American, one French and 34 Indonesian nationalities).
The flight was planned under the Instrument Flight Rules (IFR) at an altitude of 10,000 feet and the estimated elapsed time was 30 minutes with total fuel endurance of 4 hours. The area for the demonstration flight was over “Bogor” Area while the pilot might assume that the flight was approved to 20 Nm on radial 200 HLM VOR.
The available charts on board the aircraft did not contain information relating to the “Bogor” Area and the nearby terrain.The PIC acted as pilot flying while the SIC acted as pilot monitoring during this flight. In this flight, a representative of a potential customer sat on the observer seat (jump seat) in the cockpit.
At 0720 UTC, the flight took off from runway 06 then turned right to intercept radial 200 from HLM VOR and climbed to 10,000 feet.
At 0724 UTC, the pilot contacted Jakarta Approach and informed that the flight was established on radial 200 degrees HLM VOR and reached 10,000 feet.
At 0726 UTC, the pilot contacted Jakarta Approach and requested for descent to 6,000 feet and subsequently requested to make a right orbit and was approved by Jakarta Approach controller.
At 0732:26 UTC, the aircraft impacted a ridge of Mount Salak on 28 Nm HLM VOR on radial 198 at coordinate 06°42’45”S 106°44’05”E, at approximately 6,000 feet ASL.
38 seconds prior to impact, the Terrain Awareness Warning System (TAWS) audio warning “TERRAIN AHEAD, PULL UP” activated once and “AVOID TERRAIN” activated 6 times.The PIC inhibited the TAWS system assuming that the warning was a problem on the database.
Seven seconds prior to impact, the flight warning system audio “LANDING GEAR NOT DOWN” activated.
At 0750 UTC, the Jakarta Approach controller on duty noticed that the flight target disappeared from the radar monitor. There was no alert on the Jakarta Radar system prior to the disappearance of the target.
On 10 May 2012, the location of the aircraft was identified by the Search and Rescue helicopter pilot. All occupants were fatally injured and aircraft was destroyed.
The Cockpit Voice Recorder (CVR) was found on 15 May 2012. The memory module was in good condition and contained 2 hours of good quality recording.
The Flight Data Recorder (FDR) was found on 31 May 2012. It contained 471 parameters of 150 hours recording time.
Both recorders were downloaded in the NTSC facility by the NTSC experts and were assisted by the Russian experts.
A simulation test suggested that a recovery action might have avoided the collision with terrain up to 24 seconds after the first TAWS warning.
Jakarta Radar services had not established a minimum altitude for vectoring aircraft for certain areas and the Minimum Safe Altitude Warning (MSAW) did not provide warnings to the Jakarta Approach controller before the aircraft impacted.
The investigation concluded that the factors contributing to this accident were:
a. The crew were not aware of the mountainous area surrounding the flight path due to various factors resulting in disregarding the TAWS warning.
b. The Jakarta Radar service had not established the minimum vectoring altitudes and the system was not equipped with functioning MSAW for the particular area surrounding Mount Salak.
c. Distraction to the flight crew from prolonged conversation not related to the progress of the flight resulted in the pilot flying did not continue to change the aircraft heading while in orbit. Consequently, the aircraft unintentionally exited the orbit.
FACTUAL INFORMATION
History of the Flight
A Sukhoi RRJ-95B aircraft, registered 97004 and with flight number RA 36801 on 9 May 2012 was on a demonstration flight. The accident flight was the second of two scheduled demonstration flights
The navigator sent the proposed flight plans for both demonstration flights to the handling agency by means of e-mail.
At 0200 UTC1, the flight plans for the first and second demonstration flight were filed at the airport briefing office by the manager of the ground handling agency. The flights were planned at an altitude of 10,000 feet and the estimated elapsed time was 30 minutes with total fuel endurance of 4 hours and would be conducted under the Instrument Flight Rules (IFR).
The first demonstration flight was scheduled at 0400 UTC, while the second demonstration flight was scheduled at 0645 UTC.
The first demonstration flight departed from Halim Perdanakusuma International Airport 2 at 0443 UTC using runway 24 for takeoff and landed at Halim runway 24 at 0505 UTC.
At 0705 UTC, the Second In Command (SIC) of the second demonstration flight requested a clearance for start-up and pushback. The Halim Tower controller cleared for push back and engine start, and to expect runway 06.The Pilot In Command (PIC) acted as pilot flying while the SIC acted as pilot monitoring during this flight.
On board the flight were two pilots, one navigator, one test flight engineer, and 41passengers. The passengers consisted of 4 Sukhoi Civil Aircraft Company (SCAC) personnel, one from the engine manufacturer (a member of SNECMA, one of the two parent companies of PowerJet manufacturer), and 36 invited passengers (including one American, one French and 34 Indonesian nationalities). A representative of a potential customer sat on the observer seat (jump seat) in the cockpit.
Based on the number of persons on board and the amount of fuel carried, the aircraft takeoff weight was estimated at 38,500 kg (the aircraft maximum takeoff weight was 45,880 kg), and an estimated centre of gravity of 16.7% MAC-Mean Aerodynamic Chord (allowed range of the centre of gravity for takeoff was 12 up to 32.5% MAC).
The load sheet and the passenger manifest documents and all copies were taken on board the aircraft and destroyed.
The 24-hours clock in Universal Time Coordinated (UTC) is used in this report to describe the local time as specific events occured. Local time is UTC+7 hours.
Halim Perdanakusuma International Airport will be named as Halim for the purpose of this report.
At 0714 UTC, the flight was cleared to taxi to runway 06.
At 0718 UTC, the Halim Tower controller gave a clearance to maintain runway heading after takeoff then turn right to intercept radial 200 from HLM 3 VOR and climb to 10,000 feet.The SIC acknowledged the clearance from the tower.
The Halim Tower controller emphasised that turn has to be made after passing two thousand. The pilot replied that they acknowledge the message.
At 0719 UTC, the flight was cleared for take-off.
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| Crash Site |
At 0721 UTC, the flight was instructed to contact Jakarta Approach.
At 0724 UTC, the pilot contacted Jakarta Approach and informed that the flight was established on radial 200 degrees HLM VOR and reached 10,000 feet.
The Jakarta Approach controller replied that the flight has been identified on the radar display and instructed the flight to maintain 10,000 feet and continue to the area. The pilot replied “maintain 10,000 feet”.
At 0726 UTC, the pilot contacted Jakarta Approach and requested for descent to 6,000 feet. The Jakarta Approach controller asked the SIC to repeat the request.
The SIC repeated the request for descent to 6,000 feet. Subsequently, Jakarta Approach controller responded and acknowledged the request by replying “6,000 copied”. The pilot replied: “Descending to 6,000 feet”.
At 0728 UTC, the SIC requested to make a right orbit, the Jakarta Approach controller approved the flight to make right orbit at 6,000 feet.
The Jakarta Approach controller on duty stated that the radar display indicated that the aircraft was over WI(R)-4 Atang Sanjaya Training Area when requesting the orbit. The WI(R)-4 airspace area extends from ground to 6,000 feet. The area was at about 17 Nm southwest of HLM VOR.
At 0750 UTC, according to the Daily Report provided by Air Traffic Services Operation, the controller on duty noticed that the flight target disappeared from the radar monitor.
At 0752 UTC, the controller on duty attempted to contact the RA 36801 flight three times. At 0754 UTC, the Jakarta Approach reattempted to contact the RA 36801 flight and there was no reply.
At 0755 UTC, according to the Daily Report provided by Air Traffic Services Operation, the controller on duty reported the situation to the Air Traffic Services Operation Regional Coordinator (ATS Coordinator).
The ATS Coordinator made an internal coordination with Halim officer on duty regarding the position of the aircraft.
HLM is the identification code of the Halim Perdanakusuma International Airport VOR/DME.
The aircraft wreckage was found on a ridge of Mount Salak on 28 Nm HLM VOR on radial 198, at approximately 6,000 feet. According to the Flight Data Recorder (FDR) data, the impact point was recorded at coordinate 06°42’45”S 106°44’05”E.
The last recorded radio altimeter data was at 370 feet. The aircraft impacted into an 85 degree slope ridge.
Flight Preparation
The proposed flight plan had been revised and was agreed by the ground handling and Halim briefing office staff. The agreed flight plan was to fly to “Bogor Area”.
The proposed flight plan did not contain information of the area and only contained the 200 radial and 20 Nm.
The briefing office staff informed the Halim Tower controller that the flight would be performed in the “Bogor Area”. Furthermore, the Halim Tower controller informed Jakarta Approach controller of that information.
There was a different understanding between the pilots and the ATC relating to the intended flight plan.
HLM is the identification code of the Halim Perdanakusuma International Airport VOR/DME.
The aircraft wreckage was found on a ridge of Mount Salak on 28 Nm HLM VOR on radial 198, at approximately 6,000 feet. According to the Flight Data Recorder (FDR) data, the impact point was recorded at coordinate 06°42’45”S 106°44’05”E.
The last recorded radio altimeter data was at 370 feet. The aircraft impacted into an 85 degree slope ridge.
Flight Preparation
The proposed flight plan had been revised and was agreed by the ground handling and Halim briefing office staff. The agreed flight plan was to fly to “Bogor Area”.
The proposed flight plan did not contain information of the area and only contained the 200 radial and 20 Nm.
The briefing office staff informed the Halim Tower controller that the flight would be performed in the “Bogor Area”. Furthermore, the Halim Tower controller informed Jakarta Approach controller of that information.
There was a different understanding between the pilots and the ATC relating to the intended flight plan.
Both Halim Tower controller and the Jakarta Approach controller understood that the flight would be performed in the “Bogor Area”.
However, given that the previous demonstration flight reached the point on the 200 radial at 20 Nm from HLM VOR it is likely that the pilot believed that the second demonstration flight was approved to the same point.
The chart available on board the aircraft (see figure 8) did not contain the information of the Atang Sanjaya Training area. Without this map the pilot may not have been aware of the location of the Atang Sanjaya Training area and the surrounding mountainous area.
The incomplete briefing and inadequate information on the flight plan suggested that the pilot would not have been aware of the “Bogor” area including the area boundaries and altitude limitations.
Flight Altitude
The flight was planned to the “Bogor” Area at 10,000 feet under the IFR. The “Bogor” area is located at 17 Nm from HLM VOR within the MSA of HLM VOR which was 6,900 feet.
Beyond 25 Nm from HLM VOR, the minimum altitude would be the Area Minimum Altitude (AMA) which was 13,200 feet.
The Jakarta Approach controller checked the FDED and found information that the flight was a Su-30 (Sukhoi military aircraft).
After checking this information, the controller’s understanding of the aircraft type was that it was a Sukhoi military aircraft and that it was flying to the “Bogor” Area for a test flight.
The Jakarta Approach controller was not concerned about the limits of the Atang Sanjaya Training (Bogor) area which are from ground level up to 6,000 feet.
The Jakarta Approach controller assumed that a military aircraft was eligible to fly in this area. As a result, the Jakarta Approach controller approved the aircraft to descend to 6,000 feet.
Minimum Safe Altitude Warning (MSAW)
The objective of the MSAW function is to assist in the prevention of Controlled Flight Into Terrain (CFIT) accidents by generating, in a timely manner, a warning of the possible infringement of a minimum safe altitude.
Based on the replay of the radar display, the evidence showed that the flight made an orbit over the “Bogor” area (WI(R)-4) at an altitude of 6,100 feet and the Predicted Airspace (PAS) alert activated.
The Predicted Terrain (PTR) or Terrain (TR) alerts were not active while the flight was in the proximity of Mount Salak. There was no warning to the Jakarta Approach controller relating to the aircraft’s position, relative to Mount Salak.
ATC Workload
The voice recorded on the ATC ground based recorder indicated that, in the period prior to the accident, there was an intensive exchange of communication between the controller and all pilots within the ATC area of responsibility. The communications were performed continuously one after another, practically without pause.
During that period, the controller was handling 13 other aircraft. The intensive exchange of communications required the controller to transfer his attention quickly from one aircraft to another.
The quick transfer of attention might have led the controller to concentrate only on the aircraft being communicated with.
Consequently, the aircraft under his area of control which were not directly in radio communication might not have been closely monitored. This situation was one of the factors that may have contributed to the Jakarta Approach controller not noticing that the Sukhoi aircraft had disappeared from the radar screen for a period of about 24 minutes.
It was stated during interview that the Jakarta Approach controller felt over-loaded.
At that time there were no assistants or supervisor as stated in Advisory Circular (AC) 69-01, so that the controller covered the jobs of assistant, controller and supervisor. As an Air Traffic Service provider, the Angkasa Pura II is required to conduct an assessment on the capacity management including controller workload.
It has been broadly accepted that adult human working memory capacity average is seven plus or minus two unrelated items7. The term ‘working memory’ refers to a brain system that provides temporary storage and manipulation of the information necessary for such complex cognitive tasks as language comprehension, learning, and listening.
Once the limit is exceeded, one or more items are likely to be lost or transposed. The Jakarta Approach controller was controlling 14 aircraft and performing additional tasks as assistant and supervisor. These additional tasks, added to the controller workload.
Pilot Situational Awareness
During the pre-flight briefing, the ground handling agent briefed the navigator concerning information on the flight plan which had been agreed by the ground handling agent and the briefing office staff.
The flight plan contained a statement advising of the 200 radial at 20 Nm from HLM VOR. There was no information given by the ground handling agent related to the agreed area of Atang Sanjaya Training area (Bogor Area) to perform the flight.
This limited information may have given the pilot the understanding that the approved route was toward the point on the 200 radial at 20 Nm from HLM VOR and return to Halim.
Evidence from the FDR data as shown on figure 14, showed that the first and the second demonstration flights reached this point. Understanding that the approved route was to a point instead of an area, may have contributed to the pilot’s lack of awareness of the “Bogor” area.
The area chart obtained from the briefing office that was handed to the crew did not contain any terrain information.
This chart contains information of the height of the mountain, but did not depict the “Bogor Area” and had limited terrain information.
The instrument chart contained terrain contour and “Bogor Area”, and the visual chart may have provided a better understanding to the pilot that the point they intended to fly to was close to a mountainous area. These charts were not carried on board the aircraft.
At 07:30:45 when the aircraft was turning at 6,000 feet and was passing through a heading of 070°, there was a discussion between the pilot and a potential customer who was sitting on the observer seat. The pilot demonstrated the ability of the aircraft with the TAWS system by putting the terrain information on the Navigation Display.
In the direction of the flight there was no mountain visible on the display. The pilot stated that, at that moment, the terrain display was not necessary. The potential customer confirmed by stating “yes, its flat”. This information may have built an assumption for the pilot that the area surrounding the flight manoeuvre was flat, since the information was given by the TAWS and by an Indonesian who understood the area well.
At 07:27:52 while the aircraft was descending from 10,000 feet on a heading of 200° the SIC stated “dark cloud ahead”. At that time, the aircraft was heading toward th Mount Salak area. This statement indicated that the area of Mount Salak was covered by dark cloud.
At 07:29:18 while the aircraft was in the orbit area, the SIC mentioned that the
ground sometimes could be seen through the clouds. This statement indicated that the area where the aircraft was orbiting was partially cloudy.
This cloud situation was confirmed by the weather report from Darmaga BMKG station in which the cloud base was reported at 600 meters.
It is reasonable to conclude that the cloud cover prevented the pilot’s being able to see the mountainous terrain.
Due to the factors stated above, it is likely that the pilot’s were not aware of the mountainous terrain in the vicinity of the flight route.
The pilot’s lack of situational awareness may have been affected by the following facts:
At 07:32:51 and 07:32:59, the SIC was surprised by the TAWS warnings AVOID TERRAIN;
At 07:32:29 and 07:32:46, the PIC commanded the SIC to request heading 020 and descent to 1,600 feet twice even though the flight was above the mountainous area;
At 07:32:58, the PIC disengaged the TAWS SYST while the AVOID TERRAIN warning activated assuming that the warning may have been triggered by a problem with the TAWS terrain database.
CONCLUSIONS
Findings
a. The flight was planned under the IFR and was not on a published airway.
b. The aircraft was airworthy prior to the flight. There was no evidence that the aircraft had any system malfunction during the flight.
c. The flight crew had valid flight license and medical certificates. There was no evidence of crew incapacitation. Pathological examination did not find any alcohol or drug influencing the pilots.
d. The duty and rest period for the crew within 48 hours prior to the flight were within limits.
e. The ATC assumed that the flight would be performed at Bogor Area while the pilots assumed that the flight was approved to 200 radial, 20 NM HLM VOR, the evidence showed that the first and second demonstration flights reached that point.
f. The chart available on board the aircraft did not contain information of the Atang Sanjaya Training Area and only limited information of the surrounding mountainous area.
g. The PIC acted as Pilot Flying.
h. The Jakarta Flight Data Officer (FDO) entered the data of the flight into the Flight Data Edit Display (FDED) as Sukhoi 30 (Su-30) since the database on the FDED did not contain the Sukhoi RRJ-95B.
i. The FDED showed that the flight was a Su-30 (Sukhoi military aircraft), resulting in the controller believing that the flight was a Sukhoi military aircraft.
j. The crew requested descent to 6,000 feet and an orbit that was approved by ATC while the Minimum Sector Altitude was 6,900 feet.
k. The recorded radar data indicated that the aircraft orbited over the Atang Sanjaya Training Area.
l. The pilot demonstrated the aircraft feature of terrain display while turning and heading north-east and stated that it was not required at that time. A potential customer, who was sitting in the cockpit, replied ”ya, its flat”.
m. There were prolonged discussions between the pilots and the potential customer relating to aircraft fuel consumption, which may have distracted the pilots and delayed the flight crew determining the direction to return to Halim and the aircraft unintentionally exited the orbit.
n. The Jakarta Approach controller’s attention focused on controlling other aircraft with intensive communication exchange without pause.
o. There was 1 TAWS aural warning of “Terrain – Pull up” and 6 “Avoid Terrain” aural and visual warnings.
p. The PIC inhibited the TAWS system function, assuming that there was problem with the TAWS database.
q. The simulation test concluded that the TAWS was functioning properly and the impact could be avoided by appropriate reaction of the pilot up to 24 seconds after the first TAWS warning.
r. The Flight Warning System of “Landing Gear Not Down” provided additional information that the aircraft was in proximity to terrain.
s. The Jakarta Radar service had not established minimum vectoring altitude for certain areas.
t. The terrain information surrounding Mount Salak had not been inserted into the Jakarta Radar system, hence the MSAW did not provide any warning to the controller.
u. The aural warning on the Jakarta Radar system had been deactivated.
v. The aircraft impacted into an 85 degree slope ridge terrain, on the 198 radial and 28 Nm HLM VOR at approximately 6,000 feet.
w. The Jakarta Approach controller noticed that the aircraft had disappeared from the radar screen 24 minutes after impact.
x. The Jakarta Approach controller realized that the missing aircraft was a civil aircraft Sukhoi RRJ-95B only after he called the Halim Tower controller.
y. The original crew and passenger manifest and all copies were carried on board the aircraft. No copy was available from the ground handling agency.
Factors
a. The flight crew was not aware of the mountainous area in the vicinity of the flight path due to various factors such as available charts, insufficient briefing and statements of the potential customer that resulted in inappropriate response to the TAWS warning. The impact could have been avoided by appropriate action of the pilot up to 24 seconds after the first TAWS warning.
b. The Jakarta Radar service had not established the minimum vectoring altitudes and the Jakarta Radar system was not equipped with functioning MSAW for the particular area around Mount Salak.
c. Distraction of the flight crew from prolonged conversation not related to the progress of the flight, resulted in the pilot flying not constantly changing the aircraft heading while in orbit. Consequently, the aircraft unintentionally exited the orbit.
Source: http://www.dephub.go.id/knkt/ntsc_home/ntsc.htm
