On 2 April 2012, an ATR 72-201 being operated by UT Air on a domestic scheduled passenger flight from Tyumen to Surgut in day Visual Meteorological Conditions (VMC) departed controlled flight and crashed shortly after take off. Out of the 43 occupants, 29 passengers and all four crew members, were killed as a result of the impact and post crash fire and the other 10 sustained serious injuries.
An Investigation was carried out by an Air Accident Investigation Commission established by the Interstate Aviation Committee (MAK). The Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR) were recovered and their data successfully downloaded. The Non Volatile Memory from the QAR was also recovered and the data contained in it extracted.
Evidence of frozen deposits was found on the upper surface of the right elevator shortly after the accident - see the illustration below.
The right hand horizontal stabilizer showing traces of snow and ice deposits (reproduced from the Official Report)
It was noted that all other aircraft departing Tyumen around the same time other than two transit flights (both jet and turboprop types) had been de/anti iced on stand before departure. This included the aircraft on the stand adjacent to the accident aircraft which had been treated as the accident aircraft commander made a pre flight external inspection of his aircraft “without paying adequate attention to the presence of snow-and-ice deposits on critical surfaces of the aircraft”. The accident aircraft was not de-iced.
The flight sequence was reconstructed using the available recorded data. It was found that once the aircraft was moving, applicable SOPs had generally been followed with a notable exception in respect of the elevator trim which was set to -1.65 (nose up) rather than the appropriate value of -0.7 (nose up) for the actual centre of gravity position.
It was apparent that the crew had been aware during the taxi out that that the airframe was contaminated with ice and snow and the commander had instructed the First Officer to activate aircraft anti-icing system in de-icing mode. This activation had lasted for six minutes and thirty seconds before de-selection at which point “the crew observed the ice and snow contamination fall”. At no time had the crew considered abandoning the taxi out to return for de-/anti-icing. It was found that “the crew, the PIC in particular, manifested the unawareness of the ground icing danger.”
The takeoff was made with flap 15 set and pitot/static and windshield heating activated. It occurred 1 minute 30 seconds after a Boeing 737 had departed and so it was determined by the Investigation that the accident outcome was not affected by any wake turbulence encounter.
The actual weather conditions at takeoff were Wind Velocity 240/11-17 knots, Surface Visibility 10 km, Cloud base 1280 feet aal and Temperature and Dew Point both -1°С.
Climb after takeoff was made at significantly higher angles of attack than normal. The crew found that they needed to trim the aircraft in the nose down direction “almost to the structural limit.” Until the selection of flaps to zero as the AP was engaged passing 640 feet attitude at speed of 139 KCAS, there were no other unusual circumstances. However, it was noted that whilst the minimum speed for flap retraction under normal conditions was 132 KIAS, under possible (in-flight) icing conditions it was 160 KIAS.
FDR data showed that as flap retraction was completed, an uncommanded bank occurred as the aircraft stalled. This occurred before the activation of the stall warning system and the crew did not appreciate that it had occurred even though they had previously been aware of the airframe buffeting typical of an imminent stall. Activation of the stick pusher followed but even after this, “the crew did not recognise the stall of the aircraft, and, consequently, did not take measures on stall recovery (to push the control column and to extend flaps)”. Instead, “the stick pusher was overpowered by the crew” and “the control column was deflected to nose up”.
Loss of control was followed by aircraft impact with the ground at a vertical speed of around 4000 fpm in an approximately 11° nose down attitude and with the left wing about 55° below the horizontal. A post-impact fire broke out in parts of the wreckage.
The trajectory of the aircraft from take off to impact based on the recorded data is shown in the illustration below.
The reconstructed trajectory of the aircraft on departure from runway 21at 0135Z (reproduced from the Official Report)
Aircraft handling by the crew was considered. The excessive angle of attack recorded during climb after take off was attributed to a significant loss of lift. The need to trim nose down during this climb was attributed to “the redistribution of the aerodynamic forces (the change of the hinge moment) along the elevator surface due to the contamination of the stabiliser upper surface”. It was noted that neither the AFM or the FCOM included a description of this potential effect and so there were no crew recommended actions if encountered. However, it was noted that it was possible to perform such an exercise in the full flight simulator although there was no indication that the crew had been exposed to this. A simulator session to this effect was conducted and “showed that without applying the recommended procedure on stall recovery (to push the control column and to extend flaps) the recovery to normal flight was impossible”. It was considered that “if the crew had complied with the recommended procedure the altitude loss for recovery, most likely, would have been within 300-400 ft” - with the potential for recovery in the height available.
The possibility of fatigue as a circumstantial factor in the accident was considered. It was found that in the calendar month immediately preceding the accident, both pilots had worked 5 split duties when the applicable regulations permitted only 2 such duties. The Investigation considered the results of psychological team analysis and concluded that “with great degree of probability the crew performed the flight with background accumulated fatigue” noting that accumulated fatigue “provokes the symptoms of increased fatigability, inattention, distraction and, as a consequence, committing errors in piloting and decision-making”.
It was found that both pilots had gained all their operating experience after obtaining their professional pilot licences on the ATR 42/72 aircraft type. The 27 year old Commander had 2602 hours total time, all but 80 hours of this being on the ATR42/72 with UTAir. He had been promoted from First Officer to Command just over 4 months prior to the accident and had accumulated 288 hours in command. The 23 year old First Officer had 1825 hours total time, all but 60 hours of this being on the ATR42/72 with UTAir.
Both pilots had received all the required training and passed all required competency assessments. However, after a detailed review of both licence and aircraft type rating training, it was concluded that awareness of the effects of airframe ice accretion had not been adequately covered in either case. In this connection, it was noted that the ATR Guidance on Cold Weather Operations is only issued in the English language and that “in the Russian Federation there are no qualification requirements concerning the English language proficiency for pilots that fly aircraft with operation documentation in English only”. It was concluded that it was likely that the English language proficiency of both pilots was insufficient to “allow them to understand to the full extent the content of the methodological technical documentation” in such circumstances.
The Investigation concluded that the accident aircraft had been in a technically airworthy condition at take off and had remained so in flight. It was also concluded that it had been loaded in accordance with applicable limitations. Detailed attention was therefore focused on the fact that, in the presence of meteorological conditions conducive to the accretion of frozen deposits to the airframe prior to departure, no ground de/anti icing had taken place prior to that departure.
It was found that one of the three operational ground de icing vehicles had attended the accident aircraft in accordance with the instructions of the responsible supervisor but the service was expressly declined by the commander and when the supervisor became aware, he took no action. It was concluded that “due to the presence of non-removed ground icing on wing, fuselage and horizontal stabilizer surfaces, the aircraft aerodynamic performance at accident takeoff did not meet the aircraft type characteristics”. It was calculated that when the aircraft got airborne, “the actual value of the lift coefficient as compared to the type values decreased by ≈25%, with the drag coefficient practically doubled”.
The Investigation found that the previous evening, the aircraft made a flight to Tyumen in icing conditions which may have resulted in “residual in-flight icing accretion”. The aircraft was then parked for more than seven hours whilst the flight crew took split duty rest. During this time, there was a frontal passage accompanied by precipitation at near zero surface temperatures in the presence of a strong wind. These conditions resulted in the accumulation of frozen deposits on the ground and it was concluded that “the right side of the aircraft (RH wing and RH horizontal stabilizer) must have been subject to more intensive ground icing as it was situated windward during the period of most intensive fallout of precipitation”.
UTAir personnel received alerts about the presence of the ground icing conditions at the aerodrome but it was noted that “there was no mandatory procedure in the current regulations to inform a flight crew about the abovementioned alerts during a pre-flight weather briefing” although “if interested, flight crew members might have studied these documents".
It was noted also that Federal aviation regulations “prohibit flight crews (pilots) from starting a flight, if there is frost, slush or ice on the wings, fuselage, control surfaces, tail plane, propellers, power plants surfaces, windshields or ports of the pressure instruments – that is the requirement of the clean aircraft concept is introduced” and that this generic requirement is also contained in the ATR 72 AFM. However, at the time of the accident there was no basic regulatory document in force in the Russian Federation covering aircraft ground de/anti icing and procedures were left to aircraft operators to establish.
It was found that UTAir documentation in respect of ground de-icing/anti-icing was generally in accordance with the guidance contained in the current edition of ICAO Doc 9640 “Manual of Aircraft Ground De-icing/Anti-icing Operations”. It was noted that in line with existing international practice, “aircraft ground de-icing/anti-icing is not considered a part of maintenance that can be carried out by certified aviation specialists only” and was considered to be part of the ground handling function to be accepted (and where necessary requested) by an aircraft commander with the aircraft operator expected to have an effective Quality Assurance process in place.
Nevertheless, a more in-depth consideration of the State regulatory position in respect of aircraft ground de/anti icing concluded that “the separation of the conceptions of ground handling and maintenance within the aircraft operation is not fully reflected in the regulatory documents” and that specifically, “the de/anti-icing activities are not sorted out as far as the aircraft condition evaluation, decision-making on aircraft need to be de-iced/anti-iced and its quality control and responsibility are concerned” even at airports much bigger than Tyumen. The difficulty for the responsible PIC in respect of personal inspection of an airframe to determine both the need for de-icing/anti-icing treatment and its satisfactory completion if carried out was acknowledged and the poor performance and poor technical training of UTAir support personnel at Tyumen was noted.
None of this had been addressed by the UTAir Safety Management System and it was found that at the time of the accident “the safety management system was inefficient and had not become the guideline for the ordinary staff”.
The Investigation formally recorded the Immediate Cause of the accident as:
“The PIC’s decision to takeoff in violation of mandatory requirements without de/anti-icing treatment despite the fact that snow and ice deposits were present on aircraft surface and were discovered by the crew members during taxi which resulted in degradation of aircraft aerodynamic performance and stall during climbing after takeoff as well as inability of the crew to recognize stall and, consequently, failure to undertake recovery procedure. The aircraft stall occurred at the operational angles of attack right after flaps retraction with engaged autopilot before activation of the (correctly functioning) stall warning system and was caused by the loss of the wing lift effectiveness due to takeoff with non-removed ground icing. “
The Systemic Causes of the accident were identified as:
- Shortcomings in ground handling activities and staff training in UTAir-Technik that became possible because of absence of due monitoring by the Technical and Operation Supervising Directorates of UTAir airline for compliance with airline requirements regarding ground handling and aircraft ground icing protection which resulted in erroneous evaluation of aircraft conditions by the PIC and aircraft mechanic (the shift head kept himself aloof from monitoring the mechanic’s activities) after the aircraft had been on ground in icing conditions for a long time and in releasing the aircraft to fly without de/anti-icing treatment.
- Non-execution of measures on de-icing was the consequence of the erroneous coordinated decision of the PIC and the aircraft mechanic who was in charge of the aircraft pre-flight servicing after the aircraft had been parked for a long time under conditions conducive to the accumulation of ground icing on the aircraft. There was no control of the aircraft mechanic’s work on behalf of the shift engineer.
- The departure of the aircraft with non-removed ground icing became possible due to system shortcomings in the organisation of aircraft ground icing protection in the Russian Federation, that at the time of the accident was revealed in the absence of the valid basic document, that would determine the regulatory requirements as to aircraft ground de/anti-icing, including the requirements for organisations licensing and training of the personnel that were responsible for the works in question.
Contributing Factors were identified as follows:
- The shortcomings in the UTAir safety management system which contains, all in all, general issues only and is not adopted for the implementation of Airline activities in particular areas and which did not enable the identification and correction of existing safety risks in a timely manner.
- The shortcomings in the UTAir-Technic quality management system, which resulted in the neglect of certain requirements of the UTAir ground handling management manual regarding staff training and monitoring for aircraft de/anti-icing treatment which led to the situation where insufficiently-qualified staff performed the evaluation of the aircraft surface conditions and made the decision on whether the aircraft needed to be de-iced/anti-iced.
- The absence at the time of the accident of regulations that established State requirements for ground handling (de/anti-icing treatment in particular) including staff training and organisation licensing.
- The shortcomings in crew members’ initial and recurrent training as far as the danger of ground icing, its influence on the aircraft aerodynamic performance together with aircraft anti-icing system operation features and design are concerned that did not allow the crew to make the only appropriate decision to return for de-icing/anti-icing treatment after the observation of the snow and ice contamination on the wing after anti-icing system activation in de-icing mode while taxiing for takeoff.
- The methodological imperfection of the crew computer based and simulator training programs concerning the prevention of aircraft stall, identification of approach to stall and taking timely actions for recovery.
- The increasing need for a number of flight crews to perform a rapidly increasing flight schedule which, with ineffective SMS, resulted in flight instructor work deficiencies during PIC training and absence of PIC skills to take correct decisions and to strictly comply with the regulations in force.
- The possible fatigue of the crew members due to the violation of the work and rest balance while performing split flight shifts together with a large number of unused days-off.
Safety Action was taken during the course of the Investigation following a letter sent on 1 November 2012 by the Investigator In Charge (IIC) to the Director of the Federal Air Transport Agency (FATA) “with the safety recommendations issued by Investigation team relative among other issues to the improvement of quality of aircraft de-/anti-icing treatment”. On 5 February 2013, the deputy Director of the FATA Airworthiness Department issued general provisions on “Aircraft ground icing protection” which were sent to all the Agency’s Regional Offices as well as to airlines, aircraft design companies and MROs. It was also noted that with effect from 1 July 2012, a new “State Standard” covering “Methods and Procedures of aircraft de-icing/anti-icing” had been made effective.
A total of 47 Safety Recommendations were issued as a result of the Investigation as follows:
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the case for development of Federal Aviation Regulations for A/C maintenance, overhaul and repairs, as well as for ground handling taking into account domestic and international experience.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the reasonability of reviewing FAP “Airport Certification Procedures” in terms of including into the airport activities the A/C ground handling operations particularly the de-/anti-icing treatment.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the requirements of the ICAO Safety Oversight manual and develop and implement the guidance on the conformance evaluation methods to the current requirements for civil aviation organisations.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the possibility of establishing dedicated control stations for pre-flight A/C surfaces inspection for ground ice accretion (near holding point).
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the reasonability of use of the dedicated de-/anti-icing simulators for personnel training.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should include the study of ground icing influence on A/C aerodynamic performance and flight safety in training programs for personnel responsible for A/C de-/anti-icing treatment.
- that the Russian aviation authorities (and other MAK States as may be appropriate), within the framework of Federal Law No.260-ФЗ dated December 25, 2012, should continue SMS implementation in airlines, APs, maintenance A/C centres, bringing this activity into all departments of these organisations.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should review the initial training programs in aviation schools in terms of providing additional training hours (classroom and practice) for issues related to A/C operation (e.g., “Clean A/C Concept”, ground icing influence on A/C aerodynamic behaviour, as well as decision-making conditions and de/anti-icing treatment procedures and coordination with ground personnel) and use for training purposes reports and other data on investigation of accidents that have occurred because of the said reasons, including accidents involving foreign operators.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should develop and implement English language proficiency requirements for flight crew members that perform flights on A/C with documentation in English only, as well as for personnel that provide maintenance and ground handling for those A/C.
- that the Russian aviation authorities (and other MAK States as may be appropriate), because of repeal of Federal Aviation Regulation (FAP) “Requirements to Flight Crew Members for international flights”, should develop and implement the procedures for training and authorisation to international flights for Russian Federation Civil Aviation flight crew members including GA crews.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should implement recommendations related to the content of flight data analysis procedures stipulated by FAP “Flight Preparation and Operations in RF Civil Aviation” Para 5.7 for the purpose of rendering methodological support to airlines in establishing of flight data analysis systems.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should, in cooperation with the Russian Federal Service for Hydrometeorology and Environmental Monitoring (ROSHYDROMET), update the scope of mandatory meteorological information to be provided to a crew for the period of the A/C aerodrome parking before flight in case there were ground icing conditions observed within this period.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the case for reviewing COSPAS-SARSAT ELT Registry procedures in terms of mandatory registration of emergency locator transmitters by the International coordination and computing COSPAS-SARSAT centre (Moscow, Russian Federation) for A/C registered in a third countries but operated by Russian operators.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should come forward with the initiative to speed-up the launch of low orbit COSPAS-SARSAT satellites under the obligations of the Russian Federation of the support of the mentioned system.
- that the Russian aviation authorities (and other MAK States as may be appropriate) should consider the practicability of reviewing the “Manual for RF CA flight and ATC personnel selection, training and professional activity based on psychological aspects” issued on 01.01.2001, taking into account new requirements that are laid to flight and ATC personnel by operation of new A/C types.
- that Airline Managements should get acquainted with Recommendations to UTAir and examine the situation in their own flight operations procedures, flight personnel training, flight operations quality monitoring and risk prevention as well as the effectiveness of their Airline SMS and if necessary to take the corrective measures designated to improve the abovementioned processes.
- that Airline Managements should draw the flight crews' attention to the fact that in-depth awareness of A/C aerodynamic performance is needed, and that it is very unsafe to simplify or violate stipulated flight rules and AFM requirements during the flight preparation as well as during the flight.
- that Airline Managements should, in cooperation with mangers of organisations providing maintenance and ground handling for A/C, assure the compliance with requirements of the airline documentation for maintenance and ground handling with close attention to A/C de-/anti-icing procedures and to personnel training.
- that ATR 42/72 Aircraft Operators should, in cooperation with the ATR Company, organise a conference for flight and engineering specialists for the purpose of sharing experience of ATR 42/72 A/C operation.
- that ATR 42/72 Aircraft Operators should, in coordination with Federal Air Transport Agency (FATA), introduce into the flight data express-analysis the monitoring of A/C anti-icing system usage in de-icing mode while on the ground followed by analysis of each individual case.
- that ATR 42/72 Aircraft Operators should prescribe a mandatory completion of “takeoff with non-removed contaminants on horizontal stabiliser” exercise during the transition and recurrent simulator training with explanation of physical aspects of pitch forces changing.
- that UTAir Airlines should update the Airline’s SMS on the basis of shortcomings highlighted by the investigation.
- that UTAir Airlines should review flight personnel transition and recurrent training programs for foreign manufactured A/C as well as for new type of domestic aircraft in terms of A/C aerodynamics features; A/C behaviour when approaching critical flight modes; recognition of warnings triggered when approaching critical flight modes and pertinent recovery procedures; knowledge of A/C anti-icing system philosophy, limitations and efficiency; the “Clean A/C” concept, ground icing influence on A/C aerodynamic behaviour and conditions of de-/anti-icing treatment decision-making and procedures as well as procedures of coordination with ground personnel.
- that UTAir Airlines should prescribe a mandatory completion of “takeoff with non-removed contaminants on horizontal stabiliser” exercise during the transition and recurrent simulator training with explanation of physical aspects of pitch forces changing.
- that UTAir Airlines should draw the attention of flight instructors and crews to the fact that the analysis of the circumstances of certain accidents, related to the stalls, which have occurred in domestic and international aviation, have showed that the current simulator training procedures to recognise and recover from situations in question are not very effective. In most cases the crews that underwent such training in an actual flight failed to identify the approach to stall and take correct actions on aircraft recovery to flight envelope that is yet more proof of the importance of taking all the possible measures to avoid entering into critical flight modes.
- that UTAir Airlines should pay attention to the quality of flight instructor's work; to provide recurrent inspections performed by senior command personnel of trainees commissioning; to introduce pilot-instructors’ reporting during debriefing with use of training and commissioning flights’ data analysis. To draw the pilot-instructors’ attention to the importance of practical training on A/C de-/anti-icing procedures when commissioning flight personnel and of keeping pertinent records.
- that UTAir Airlines should pay attention to the quality of debriefings and training and ensure they use all available training facilities and documentation; to eliminate formalities during debriefing.
- that UTAir Airlines should develop and implement a common format of flight personnel commissioning documentation that will allow to assess the commissioning process (for example, recording type of approach system used as well as approach modes: e.g., A/P, FD etc., as well as meteorological conditions etc.).
- that UTAir Airlines should provide for the keeping of records of approaches made by PICs in actual conditions of assigned weather minima.
- that UTAir Airlines should make use of the Fatigue Risk Management System (FRMS) Implementation Guide issued in July 2011 by ICAO, IATA and IFALPA in order to monitor flight personnel fatigue risks.
- that UTAir Airlines should, before flights performing in periods when ground icing is possible, perform inspections (audit) of all destination APs and subcontractors of ground handling for availability of trained personnel and facilities for A/C de-/anti-icing treatment.
- that UTAir Airlines should develop procedures to check A/C conditions after anti-icing treatment depending on the AP and the maintenance organisation facilities.
- that UTAir Airlines should ensure strict compliance with flight personnel work and rest limitations as well as arranging leave for crew members in a timely manner.
- that UTAir Airlines should, when rostering crew members for flights, take into account the influence of social factors (such as a birthday, a wedding etc.) on the psychoemotional state of personnel.
- that UTAir Airlines should, within the framework of the Airline SMS, guarantee the quality of work performed by subcontractors and their compliance with procedures established by the Airline paying special attention to de/anti-icing treatment.
- that UTAir Airlines should review the quality of operation of the Airline Directorates.
- that UTAir Airlines should rectify other shortcomings revealed during the investigation.
- that the General Director of Roschino (Tyumen) Airport should consider the possibility of establishing a ground handling organisation that will meet the State requirements.
- that Federal Air Transport Agency (FATA) Regional Offices should ensure strict compliance with the requirements of Para 2.3.1 of Russian Federation Government Decree No.609 (PRAPI-98) of 18.06.1998 in terms of initial actions and governing of all means and facilities of agencies taking part in the search and rescue operations.
- that Federal Air Transport Agency (FATA) Regional Offices should check the emergency response plans of Airports and Airlines.
- that the State ATM Corporation should guarantee strict compliance of ATC officers with ATC Procedures when they are preparing for duty and during their duty shifts, particularly when maintaining radio communications.
- that the Ministry of the Russian Federation for Civil Defence, Emergency Management and Natural Disasters Response (EMERCOM) should, with the involvement of IAC, FATA and the Investigative Committee of the Russian Federation, conduct training for command staff of services that perform search-and-rescue operations at the accident site intended to study the procedures of coordination with the said services especially in terms of documenting the search and rescue operations, A/C fragments displacement and structure cutting operations.
- that ATR should consider the case for the introduction into the appropriate documentation (FCOM, FCTM, Cold Weather Operations etc.) of a description of the detrimental effects of ground icing accretion on different aircraft parts as well as its influence on the A/C performance and handling.
- that the Certification Authorities of the States of Design should review the current procedural approach to both the checking of aircraft surfaces for accreted contaminants before the flight and to the monitoring of aircraft state after de/anti-icing treatment and consider the introduction of a requirements to mandate the equipping of at least those A/C types whose aerodynamic performance is very sensitive to ground icing with an on-board system for automatic detection of ground icing conditions and the corresponding notification to flight crews.
- that EASA and other simulator certification authorities should consider the possibility of adding into the simulator data-package the capability to simulate an unexpected or sudden aircraft stall at any stage of flight.[See also NTSB Recommendation А-10-022 made as a result of the investigation into the DHC8-400 fatal accident on February 12, 2009]
- that ICAO should consider the case for amending Annex 6 to the Convention on International Civil Aviation relating to mandatory installation of an AOA indicator in the cockpit.
- that the Head of the Personnel Training Centre, NPP (Tyumen) should correct the shortcomings contained in the present report.
The Final Report of the Air Accident Investigation Commission of the Interstate Aviation Committee (MAK) was completed on 12 July 2013 and subsequently made available in English translation.