Georgian Airways CRJ1 at Kinshasa on Apr 4th 2011, impacted ground during go-around, possible microburst

Last Update: November 2, 2016 / 16:48:45 GMT/Zulu time

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Incident Facts

Date of incident
Apr 4, 2011

Classification
Crash

Flight number
834

Aircraft Registration
4L-GAE

ICAO Type Designator
CRJ1

Airport ICAO Code
FZAA

An Airzena Georgian Airways Canadair CRJ-100 on behalf of the United Nations Organisation (UNO), registration 4L-GAE performing flight 834 from Kisangani to Kinshasa N'Djili (Democratic Republic of Congo) with 29 passengers and 4 crew, was on an instrument approach to Kinshasa N'Djili's runway 24 around 13:30L (12:30Z) in torrential rain, thunderstorms and low visibility, when the airplane missed the runway, broke up into several parts upon ground contact and came to rest off the runway abeam the military apron. 33 occupants perished, only one occupants survived with serious injuries, the airplane was destroyed.

The (flight data and cockpit voice) recorders were recovered on Apr 5th.

A witness on the ground said that the all white aircraft apparently caught a windshear at a height of about 20 meters (65 feet) and basically fell down.

The surviving passenger reported, that the airplane was "rocked" violently on approach to Kinshasa.

The United Nations reported that only one of the 29 passengers and 4 crew survived the crash.

Airzena Georgian Airways said deeply shocked, that all 29 passengers and 4 crew perished in the crash, but later confirmed one of the 29 passengers survived.

Ndjili's runway 06/24 is officially 4650 meters long, however due to very poor runway condition the threshold of runway 24 had to be displaced leaving a runway length of about 3400 meters available.

DR Congo's Bureau Permanent d’Enquêtes d’Accidents et Incidents d’Aviation (BPEA) released their final report via ICAO concluding the probable causes of the accident were:

Probable cause of the Accident:

The most probable cause of the accident was the aircraft‟s encounter with a severe Microburst like weather phenomenon at a very low altitude during the process of Go Around. The severe vertical gust/downdraft caused a significant and sudden pitch change to the aircraft which resulted in a considerable loss of height. Being at very low altitude, recovery from such a disturbance was not possible.

The possibility of a somatogravic illusion caused Loss Of Control (LOC) as the primary cause of the accident, was also discussed by the investigation team. This was ruled out based on available evidence which showed that during the Go Around, the crew had initiated the climb at 1256 32 and had thereafter, maintained a climbing attitude for the next 12 seconds. At 1256 44, the aircraft experienced a sudden and steep nose down attitude change without a corresponding control input by the crew (as shown by FDR), Hence, Somatogravic Illusion caused Loss of Control was ruled out as a cause of accident.

Probable contributing factors:

- The inappropriate decision of the crew to continue the approach, in face of extremely inclement weather being displayed on their weather radar, was probably the principle contributing factor responsible for the accident.

- Lack of adequate supervision by the Operator to ensure that its crew complied with established procedures including weather avoidance procedures and Stabilized Approach criteria, was a probable contributing factor.

- Inadequacy of Georgian Airways Training program for upgrade to Captain was a probable contributing Factor.

- Lack of effective oversight of Georgian Airways by Georgian CAA was a probable contributing factor.

- Lack of appropriate equipment at Kinshasa airport for identification and tracking of adverse weather phenomenon, resulting in failure by ATC to provide appropriate early warning to the aircraft, was probably a contributing factor.

- ATC not declaring the airfield closed when visibility dropped below Minima was a probable contributory factor.

The BPEA reported the captain (27, ATPL, 2,811 hours total, 1,622 hours on type) was pilot flying, the first officer (22, CPL, 495 hours total, 344 hours on type) was pilot monitoring.

Descending towards Kinshasa the crew received weather information from ATC reading: "wind 210 degrees, 8 knots, visibility 8 KM, thunderstorm over the station, scattered cloud at 2500 feet, few Charlie Bravo 3000 feet, Charlie Bravo located north-east, south west and west, broken 12000 feet, temperature 33, dew point 23, QNH 1008, trend NOSIG."

The crew however noticed significant weather depicted around and over the aerodrome on their weather radar.

The aircraft performed a LOC approach to runway 24. The BPEA then described the events as follows:

As the aircraft came close to the airfield, the co-pilot sighted the runway on his right one o‟ clock position, when the aircraft was about 9.7 nautical miles from displaced threshold of runway 24. The PIC too, sighted the runway when the aircraft was about 6.4 NM away from Threshold. At that stage, the aircraft speed was 210 knots, altitude was 3250 feet (or about 2252 feet above ground level) and the aircraft was in clean configuration. The crew decided to continue their Approach. PIC disengaged the autopilot, turned towards the runway and gave instructions to co-pilot to configure the aircraft for landing.

The crew managed to regain Localizer path and align the aircraft to the runway by the time they were 2 NM from the threshold.

At around this time, Kinshasa airfield was affected by a Squall Line, as depicted by the satellite images obtained from EUMETSAT. These images indicate that the Squall Line with very low cloud base approached Kinshasa from the North East (about 5 o‟ clock position to the aircraft‟s final approach path).

As the aircraft came on short finals, it encountered rain. By this stage, the aircraft was below the Minimum Descent Altitude (MDA) for Localizer Approach for Runway 24. MDA for Localizer Approach for Runway 24 is 1470 feet or 472 feet Above Ground Level (AGL). The crew switched on wind shield wipers. As they descended further to about 224 feet AGL and runway was not in sight, the crew decided to carry out a Go Around.

During the process of Go Around, a positive rate of climb was established with appropriate airspeed.

While climbing through an altitude of 1395 feet (or 397 feet AGL); the aircraft encountered a severe weather phenomenon (probably a microburst). Wind shear warning came on. The aircraft pitched significantly nose down (from about 4-5 degrees nose up attitude to 7 degrees nose down attitude) in a very short time. The aircraft rapidly lost height. Before the crew could react to the pitch down and recover from the steep descent, the aircraft impacted the terrain.

The aircraft impacted ground abeam the displaced threshold runway 24 about 170 meters left of the runway at a heading of about 220 degrees magnetic and came to a stop within 400 meters past the point of impact.

28 passengers and 4 crew died in the impact, one passenger survived with serious injuries.

The BPEA reported: "To determine the nature and movement of weather that affected Kinshasa airfield and its surroundings on 04 April 2011, assistance was requested from EUMETSAT. A series of Satellite images in Infra-Red band for the time period between 1142 hours and 1342 hours for 04 April were obtained and analyzed. A study of these images indicates that a Squall Line comprising of significant cloud mass with very low cloud base, transited through Kinshasa Terminal Area from North East Direction, affected Kinshasa Airfield, before moving away in South West direction. The images also confirm that the cloud mass associated with the Squall Line was growing in size during its passage over Kinshasa airfield. Its speed of movement was estimated to be 40-50 KMPH. Kinshasa meteorological observers, not being equipped with weather radar, were not aware of the approach of this severe weather system."

The flight data recorder showed that the aircraft did not overfly the final approach fix but passed abeam to the south in clean configuration and idle power at 208 KIAS. 4.2nm before the threshold the airspeed had reduced to permit setting flaps 8, flaps 8 were selected and the gear was selected down. Engines remained at idle.

Rapid oscillations in elevator movements and short period movements of the yaw damper were recorded over a period of 27 seconds. Flaps 30 were extended at 178 KIAS, flap overspeed warning resulted as the speed was above flap 30 extension speed, about one minute prior to impact.

The aircraft descended through 500 feet AGL at 181 KIAS (46 knots above Vref), flaps 30 extended, idle power. The airspeed increased to 185 KIAS, flaps 45 were selected. Shortly thereafter the aircraft intercepted the localizer.

38 seconds prior to impact the aircraft reached the minimum descent altitude (MDA), 472 feet AGL, at 173 KIAS, the flaps reached 45 degrees 35 seconds prior to impact, 31 seconds prior to impact the flight directors were disengaged and the captain reverted to flying raw data, 27 seconds prior to impact the aircraft entered rain, the windshield wipers were engaged 23 seconds prior to impact already below 300 feet AGL. 19 seconds prior to impact, descending through 224 feet AGL, the first officer reported "No, I don't see anything, let's go around", 2 seconds later the captain called "Go Around, Flaps 8" at 218 feet AGL, thrust was increased to about 89-90%, the pitched was raised to 8 degrees nose up.

6 seconds prior to impact, while climbing through 397 feet AGL at 149 KIAS and 4-5 degrees nose up, an external influence caused the aircraft to pitch down to 7 degrees nose down within the next 5 seconds, a windshear warning activated, the pitch decreased further to 9-10 degrees nose down and the speed increased to 180 KIAS, the aircraft rapidly lost height, the crew attempting to pull the aircraft out of the dive evident by elevator deflection.

The BPEA analysed that the first officer's sighting of the runway probably "preciptated" the captain's decision making processes resulting in the decision to attempt landing. The BPEA continued: "When the PIC disengaged the autopilot to turn towards the runway at 1254 52, the aircraft was only 6.4 NM from Threshold, in clean configuration, at 3267 feet of altitude (about 2270 feet on RADALT) and flying at 210 knots IAS. To attempt a landing from this stage of flight, in the presence of extreme weather being indicated on the weather radar, is indicative of inappropriate decision making process in the cockpit and inadequate CRM. While carrying out the high speed and unstabilized Approach, the crew probably faced a situation overload. This may have also affected crew‟s decision making capability."

The BPEA analysed:

No call out of changeover to QNH at Transition Altitude of 5500 feet, no carrying out of Landing check list / obtaining landing permission / reporting on short finals as demanded by ATC, no callout by PNF of runway visible or not at MDA, continuing approach having entered rain when below MDA, are just such examples.

Aircraft speeds were significantly higher than recommended during the Approach. Over speed warning was audible even at 300 feet AGL on Approach.

Stabilized Approach procedures were not adhered to by the crew.

Weather avoidance procedures were not adhered to by the crew.

Windshear escape manoeuvre was not carried out as per SOP.

Go Around actions by the crew were also not in conformity with the Aircraft Operating Manual (Thrust was not increased to Go Around thrust, pitch attitude was not raised to Go Around attitude and Landing gear was not retracted). The normal Go Around N1 RPM should have been about 92-93% for the prevailing altitude and temperature. The FDR indicates that the crew opened throttles only to 88-89 % during the Go Around (according to Bombardier, the engine setting selected by the crew would also have allowed a successful Go Around). If standard operating procedure for Go Around had been adhered to (by opening thrust to Go Around Thrust and raising undercarriage), the aircraft would have reached a higher altitude by the time it encountered the severe weather and the chances of avoiding an accident may have improved.

The BPEA analysed that only one flight simulator sortie was required during the command upgrade of the captain in 2010 and stated: "Only one simulator flight for first time upgrade to a Captain on an aircraft like the CRJ may not be considered adequate. Such a syllabus is also not in accordance with similar upgrade training programmes being carried out in other countries around the world."

The BPEA analysed: "It is common knowledge that Go Around maneuver is carried out very few times in routine line flying. It is only in the Simulator while doing non - normal procedures / Emergency Procedures that Go Arounds can be practiced sufficient number of times. The PIC had done only one Simulator sortie during his Command Upgrade training and hence, probably did not have many opportunities to practice Go Arounds. Due to above mentioned factor, it is possible that the PIC may have not pressed the TOGA button while performing Go Around on the day of the accident. The PIC had been a First Officer on Boeing 737 before commencing his command training on the CRJ. There is a significant difference in the location and operation of TOGA button on the Boeing 737 as compared to a CRJ."

The BPEA analysed: "Kinshasa ATC did not declare the airfield closed when the visibility reduced below the minimum visibility of 2400 metres needed to fly a Localizer Approach. If the airfield had been declared closed, UNO 834 would not have continued its approach and the accident may not have occurred. ATC used the term NOSIG when conveying weather information to UNO 834. The term NOSIG implies that no significant change is expected in the weather in next 30 minutes, hence this term should not have been used when weather was indeed changing. Probably the ATC used this term as a matter of habit and without understanding its significance."

The BPEA analysed the last few seconds of flight:

During the process of Go Around, the aircraft had to fly through the same very airspace where „Magenta‟ had been indicated during the Approach all along. It is while climbing through this airspace, at about 397 feet AGL that the aircraft was affected by a severe external disturbance caused probably by a Microburst type phenomenon. The wind shear warning came on. The vertical gust/down draft pitched down the aircraft from about 4-5 degrees nose up to 7 degrees nose down, in a very short time. The vertical gust strength was calculated to be of the order of 40 to 50 feet per second. The aircraft rapidly lost height. Being at very low level, the crew did not have sufficient time to recover from the effects of this encounter. Recovery from the above mentioned significant upset, caused by the severe external disturbance at such low altitude, could not have been possible.

The significant and instantaneous elevator (nose up) deflection recorded on the FDR in the very last second of flight can probably be indicative of the instinctive response of the crew to the impending impact with the ground.

Metars:
FZAA 041600Z 35010KT 9999 SCT018 FEW025CB BKN100 26/22 Q1008 SECT CB NW NOSIG
FZAA 041500Z 36018KT 9000 SCT020 FEW028CB BKN110 26/23 Q1008 CB NE-E NW BECMG NSW
FZAA 041500Z 36018KT 9000 SCT020 FEW028CB BKN110 26/23 Q1008 BECMG NSW
FZAA 041400Z 34004KT 9000 TS SCT020 FEW028CB BKN110 24/23 Q1008 CB SECT NE-NW BECMG NSW
FZAA 041300Z 18020KT 0500 +TSRA SCT022 SCT028CB BKN110 28/22 Q1008 CB SECT NE-E-SE-W BECMG 1500
FZAA 041200Z 35008KT 9999 SCT015 FEW030CB 33/23 Q1009 CB NE/SE NOSIG
FZAA 040800Z 27004KT 9999 FEW018 BKN110 29/23 Q1012 NOSIG
FZAA 040700Z 00000KT 9999 FEW014 BKN120 25/23 Q1013 NOSIG
Incident Facts

Date of incident
Apr 4, 2011

Classification
Crash

Flight number
834

Aircraft Registration
4L-GAE

ICAO Type Designator
CRJ1

Airport ICAO Code
FZAA

This article is published under license from Avherald.com. © of text by Avherald.com.
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