Tatarstan B735 at Kazan on Nov 17th 2013, crashed on go-around

Last Update: December 26, 2015 / 23:26:07 GMT/Zulu time

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Incident Facts

Date of incident
Nov 17, 2013

Classification
Crash

Aircraft Registration
VQ-BBN

Aircraft Type
Boeing 737-500

ICAO Type Designator
B735

On Dec 24th 2015 the Interstate Aviation Committee (MAK) released their final report in Russian concluding the probable causes of the crash were:

systemic weaknesses in identifying and controlling the levels of risk, non-functional safety management system in the airline and lack of control over the level of crew training by aviation authorities at all levels (Tatarstan Civil Aviation Authority, Russian Civil Aviation Authority), that resulted in an unqualified crew being assigned to the flight.

During the go-around the crew did not recognize that the autopilot had disconnected resulting in the aircraft impacting ground in a complex spatial position (nose up upset). The captain, pilot flying, lacked the skills to recover the aircraft from the complex spatial upset (lack of Upset Recovery), that led to significant negative G-forces, loss of spatial orientation sending the aircraft into a steep drive (75 degrees nose down) until impact with ground.

The go around was required because the aircraft on its final approach arrived in a position from which landing was impossible as result of a map shift by about 4000 meters (aircraft systems determining the position of the aircraft in error), the inability of the crew in those circumstances to combine aircraft control and navigation with needed precision, and the lack of active support by air traffic control during prolonged observation of significant deviation from the approach procedure.

The following factors, listed in logical order but not sorted by priority, contributed to the accident:

- The captain not having had primary flight training

- Flight crew members being allowed to upgrade to Boeing 737 without satisfying the required qualifications including the English language

- Methodical shortcomings in retraining as well as verification of results and quality of training

- Insufficient level of organisation of flight operations at the airline, which resulted in failure to detect and correct shortcomings in working with the navigation equipment, pilot technique and crew interaction, including missed approaches

- Systematic violation of crew work and rest hours, a large debt of holidays, which could have resulted in accumulation of fatigue adversely affecting crew performance

- Simulator training that lacked a missed approach with intermediate height and all engines operating

- Increased emotional stress to the flight crew before deciding to go around because they could not establish the position of their aircraft with the necessary precision to accomplish a successful landing

- Violation of the principle "Aviate, Navigate, Communicate" by both flight crew and air traffic control, which resulted in the flight crew not following standard operating procedures at the time of initiating the go around because the pilot monitoring was diverted from his duties for a prolonged period and did not monitor the flight parameters

- The fact that the crew did not recognize the autopilot had disconnected and delayed intervention by the crew, that resulted in the aircraft entering a complex spatial position (nose up upset)

- Imperfection of simulator training programs for Upset Recovery Procedures as well as lack of criteria for assessing the quality of training, which resulted in the crew being unable to recover the aircraft from the upset

- The possible impact of somatogravic illusions

The non-addressing of prior accident investigation recommendations, geared towards elimination of risks and establishing risk level management, had prevented the prevention of this accident:

- Lack of proper supervision of issuance of pilot certificates in accordance with achieving specified requirements and qualifications

- Failure of safety management system (SMS) in the airline, lack of guidelines for SMS development and approval, lack of a formal approach to approve/agree on SMS and pilot training by the related authorities

- Deficiencies in aviation training centers' performance and absence of verification of training quality

- Lack of requirements for flight crew to be proficient in English Language for retraining on foreign aircraft types and lack of formal approach to verify language proficiency

- lack of formal approach to conduct periodic verifications of flight crew qualification

- systematic violation of crew work and rest times

- lack of training of flight crew on go arounds from intermediate heights in manual control potentially leading to complex spatial psoition (e.g. nose high upset)

- The map shifts in aircraft without GPS without training of crew to operate in such conditions

- Lack of active assistance by air traffic control when the approach procedure was deviated from over a prolonged period of time

- Breach of principle "Aviate, Navigate, Communicate"

The MAK reported the crew had flown the leg to Moscow Domodedovo resulting in a safe landing despite turbulence on final approach and windshear at 60 meters/200 feet AGL and gusting winds on touch down.

The captain (47, ATPL, ILS Cat I, 2,784 hours total, 2509 hours on type) was pilot flying, the first officer (47, CPL, ILS Cat II, 2,093 hours total, 1,943 hours on type) was pilot monitoring.

The return flight was properly prepared, the aircraft was loaded within limitations and CG at 21% MAC well within limits. Departure and cruise flight were without incidents.

Descending into Kazan the aircraft was handed off to Kazan Approach and was cleared to descend to FL070 (2130 meters). Approach control subsequently advised that the aircraft was flying 4km to the left of the assigned track, which the crew replied to "Thank you".

The aircraft was subsequently vectored for an ILS approach to runway 29 and was cleared to descend to 500 meters. The crew subsequently received clearance for the ILS approach, the MAK annotated the point of ILS approach initiation was significantly different to the procedure (closer to the runway than Final Approach Fix), the localizer was not captured by the autopilot as result and the autopilot remained in altitude hold. The aircraft established on final approach, about 4km to the right of the extended runway center line, and was handed off to tower. The crew saw the CDI fly full left, and selected the heading bug 40 degrees to the left of the runway heading, insufficient however with the current winds to re-acquire the extended runway center line.

The crew reported to tower 14km before touchdown, landing gear was down, ready for landing, was informed of winds from 220 degrees at 9m/s gusting to 12m/s (17 knots gusting 23 knots) and received clearance to land on runway 29 and read back the clearance.

The flaps were set to 30 degrees, the airspeed was reduced to between 130 and 135 KIAS, the CDI remained in the full fly left position.

About 2km before touchdown the CDI began to move and the localizer was captured, the aircraft began to descend, the crew selected a vertical speed of 1200 fpm in order to descend. The aircraft settled on the localizer. The GPWS announced "one thousand", the captain announced "one thousand, stabilized, no flags", the approach was clearly unstabilized however and the crew had to take the decision to go around, however, continued to visually look out for the runway. The first officer finally caught sight of the PAPIs, announced "Oh, everything here, the bar is below us, 4 whites, we are high."

About one minute after receiving landing clearance and about 13 seconds after that remark by the first officer the crew reported they were going around due to "non-landing" position, the captain engaged the TOGA button which disconnected the autopilot and required the crew to continue manually on flight director. The aircraft was about 1km before touchdown descending through 270 meters/700 feet AGL (editorial note: that height would be appropriate for 5km before touch down on a 3 degrees glideslope), the autopilot had established the aircraft on the localizer/extended center line of the runway, never captured the glide path, autothrust maintained an airspeed between 130 and 135 KIAS. The first officer engaged in a communication with tower to establish what altitude the aircraft should climb to, a misunderstanding (600 meters instead of 500 meters) resulting in an erroneous readback prompted tower to reiterate the clearance to 500 meters, all in all that communication lasted for 20 seconds.

After initiating the missed approach the crew selected the flaps to 15 degrees, the flaps remained in that position until impact, the aircraft climbed to 700 meter/2300 feet then entered a steep dive and impacted ground at about 450 km/h airspeed (242 KIAS) and a nose down attitude of 75 degrees between the runway, main taxiway and taxiway B 43 seconds after initiating the go-around. All occupants perished, the aircraft was completely destroyed and was partially burned in the resulting ground fire.

The investigation concluded after examining the wreckage, that all damage to the airframe was the result of impact and post impact fire, prior to impact all aircraft systems were working normally. However, the investigation found particles inside the power control unit (PCU) driving the left hand elevator that could have partially jammed the actuator and may have resulted in excessive control forces necessary to move the elevator or could have resulted even in seizure.

The MAK reported the aircraft was equipped with a Flight Management System (FMS) that determines the current position of the aircraft using the Inertial Reference System and ground based navigation aids.

The IRS must be properly aligned prior to departure, nonetheless, a drift by about 2nm per hour due to natural drift is to be expected. The error and error rate may increase if the initial position is incorrectly entered/aligned.

The IRS data are persistently adjusted using ground based naivation equipment, e.g. multiple DME transmitters or VOR/DME. The aircraft was not equipped with a GPS.

The aircraft's AOM stated, that the FMS was not approved as independent source of position information. The necessary accuracy of navigation can only be achieved by using ground based navigation aids.

The investigation was able to download the flight data recorder and restore the cockpit sound recorder, which had suffered substantial damage to both casing and memory module, 30 minutes of 4 channel audio could be downloaded after repairs and were found to be consistent with the last 30 minutes of the accident flight.

The MAK reported that the French BEA performed a sensorical simulation with the aim to model how the crew could lose spatial orientation. The model suggested that after initiating the go around the feel of the pitch angle of the crew and the actual pitch angle were in agreement until about +14 degrees, when the nose rose further to 25 degrees the crew still felt the pitch increase to 17 degrees. Subsequently, when the actual pitch began to decrease the felt pitch continued to increase until reaching +25 degrees, in this phase first nose down inputs are recorded on the flight controls. The felt pitch and actual pitch subsequently completely separated, as the aircraft settled in the dive further increasing nose down inputs were recorded.

The MAK reported that the British AAIB performed simulations with the aim to determine whether somatogravic illusions were present. The AAIB concluded that in the absence of proper control of the instrument readings the crew could have perceived during the transition from climb to dive after the missed approach, that the aircraft was flying inverted.

The MAK performed simulator tests with a number of pilots having them go through a scenario similiar to the accident flight, in particular forcing a go around at intermediate height with the autopilot disconnecting at the initiation of the go-around by pressing the TOGA button. The MAK reported that the vast majority of crews coped well with the scenario but found it difficult to master reporting highly increased stress levels, especially when the pilot monitoring did not provide full assistance. A number of pilots, although the autopilot disconnect aural and visual alerts are very distinct and have high attraction potential, did not catch the fact, that the autopilot had disconnected, several silencing the alerts by pressing the AP disconnect button, a number (about 42% of the pilots tested) not recognizing the alert at all and therefore responding with a substantial delay or not reacting at all. None of the pilots participating in the test was able to answer all questions to the procedures correctly, the MAK reported that 28% even believed the go around was automatic on autopilot despite the AP disconnect alert indicating lack of knowledge and a substantial gap between theoretic knowledge and practical skills.

Of all pilots participating in the test only one third mastered the go around successfully. Only 28% attempted to achieve a suitable pitch angle after initiating the go around aiming for +15 degrees of nose up, others began to react only between +20 and +37 degrees of nose up attitude and airspeeds as low as 90 KIAS with stick shaker activation. None of the pilots was able to level off at the assigned altitude.

In a second part of the experiment a test pilot produced a pitch up upset similiar to the accident flight and then let the participating pilot recover the aircraft. None of the pilots took the right decisions and none was able to recover the aircraft. The most common mistake was to believe, the control wheel would return to the neutral position on its own, this mistake however resulted in a substantial acceleration of the nose down movement resulting in rapid increase of the dive and vertical accelerations between +0.5G and -1.2G. The MAK annotated that in real flight such an acceleration likely causes the temporary and permanent incapacitation of passengers, cabin crew and even flight crew and may cause injuries to occupants.

The common mistakes during the upset recovery noted by the MAK were non-optimal application of flight controls especially if the aircraft is in a bank, no reselection of flaps in order to adjust to the current airspeed resulting in flap limit exceedance and loss of additional height, the non-use of speed brakes. The MAK reported, that after demonstration of the correct upset recovery technics almost all pilots were able to apply the technics and recover the aircraft, suggesting that the result of the experiment was mainly the result of lack of pilot training with respect to upset recovery.

The MAK analysed that at the time, approach control reported the aircraft 4km to the left of the approach track, the deviation was caused by the IRS, which had drifted 4km off the correct position. The crew changed the heading bug as result but the change was insufficient to acquire the correct track.

The MAK analysed that the crew was using single autopilot Approach mode, which does not permit automatic go arounds (unlike the dual autopilot approach mode) and would not perform automatic flare, touchdown and roll out. TOGA therefore automatically disconnected the autopilot and required the crew to continue manually on flight director.

The MAK analysed that according to flight data recorder and actual taxi path at Moscow the IRS was not correctly aligned at departure showing a "map shift" of 2km to the south while taxiing out for departure, it is probable that the crew entered incorrect coordinates, possibly the coordinates stored by the FMS from the previous flight to Moscow.

The MAK analysed that the investigation discovered two scenario in which excessive control forces on the elevator control could be needed due to jamming of the PCU (which likely resulted in the MAK cancelling the airworthiness certificate of the Boeing 737, see Russia suspends airworthiness certification for Boeing 737s, but does not prohibit operation of 737s).

The MAK continued analysis however, that there were no such signs on the accident flight evidenced by flight data recorder as well as lack of related comments by flight crew.

The MAK analysed that the investigation could not identify, if, when and where the captain had undergone initial flight training. Of course the captain had acquired certain piloting skills evidenced by passing the type rating upgrade course on a certified aviation training center and more than 2500 hours logged on the 737. At the same time the captain showed serious lack of skills in emergency situations. The investigation established that Russia's Civil Aviation Authority Northwest Regional Center issued the ATPL to the captain only 8 months after he allegedly acquired the license. The MAK stated that this was not a case of a forged pilot's license, however, a case of lack of supervision and monitoring of pilot certificates by Rosaviatsia.

The MAK analysed further that the airline had all documents and possibilities at hand to identify that the ATPL had been granted to the captain unjustifiedly. For example, the MAK reasoned, the captain was conducting manufacturing flights to the airline when he, according to documents, was receiving training and passed examinations. Even a cursory check of the documents would have unveiled these discrepancies.

The MAK analysed that the Civil Aviation Authority of Tatarstan issued the ATPL formally, a reason for the (undue) issuance of the license was not provided.

The MAK analysed that the first officer failed two exams for acquiring the theoretical commercial pilot's license, on the third attempt he passed with 100% putting the result into serious doubt. The type rating took substantial more time (about 6 months) than normal, with a large pause between theoretical and simulator training. That simulator training was considered inadequate. For example the MAK annotated the training was conducted by freelance instructors invited by the airline, there were two such instructors used on flight training devices and 5 on the full flight simulator.

The MAK therefore concludes that the pilot training in general was not carried out according to the principles set forth in FAR-23.

The MAK analysed that both pilots were suffering from accumulation of fatigue. Although officially there had been sufficient rest time, evidence showed that there was substantial revision of the work times leaving insufficient rest times to compensate for accumulated fatigue.

The MAK analysed that air traffic control observed the significant deviations from the approach procedure but did not offer assistance, i.e. vectors, to correct and compensate. The controller stated in post accident interviews he had no idea he could have offered vectors. He believed, in contradiction to existing air traffic control regulations stating "the need for vectoring is determined by air traffic controller assessing the current air traffic situation. Vectors are offered to provide navigational assistance to flight crews.", he needed an active request by the crew to provide vectors.

The MAK continued that even after turning final the aircraft was substantially to the right of the extended runway center line, clearly observed on radar, the controller therefore should at least have advised the crew of the significant deviation from the final approach course and should have recommended a go around.

The MAK analysed that the investigation's "fitness experiment" showed that the vast majority of airline transport pilots failed the unexpected go around, only about 30% more or less succeeded to perform the go around.

The MAK analysed that the accident captain - just like the survey in the experiment showed - anticipated an automatic go around controlled by the autopilot and did not expect the autopilot to drop offline. In addition he did not register the autopilot disconnect indications, just like almost half of the pilots participating in the experiment.

The MAK analysed that a survey amongst Tatarstan pilots revealed, that in full flight simulator lessons they always used dual autopilot when the approach mode was being used, which would result in an automatic go around on autopilot upon pressing the TOGA button. However, when in real flight and the crew did not intend to perform an automatic landing, they always used single pilot approach mode, which disallows an automatic go around.

The MAK analysed that the priority in handling aircraft is "Aviate, Navigate, Communicate". When the go-around was initiated priority was on "aviate", however, at that time the first officer engaged in an ATC communication that lasted for 20 seconds and turned his attentation away from monitoring flight instruments and the actions by the pilot flying. Therefore he did not perform according to standard operating procedures, for example missed to call out "positive rate of climb", failed to point out the exceeding pitch angle, failed to point out speed deviations, ... Only 20 seconds after the go around was initiated the first officer "returned to the cockpit" and pointed out that the landing gear was still extended.

The MAK analysed that one of the factors leading to loss of situation awareness could have been zero or negative gravity, which would not only cause the state of weightlessness, but would also cause all loose items in the cockpit to "float" including dirt and dust always present in a cockpit. As this is usually very sudden, it has a "chilling" effect on flight crew, apart from dirt and dust entering eyes and noses of flight crew limiting sight and breathing.
Incident Facts

Date of incident
Nov 17, 2013

Classification
Crash

Aircraft Registration
VQ-BBN

Aircraft Type
Boeing 737-500

ICAO Type Designator
B735

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