Moscow-Vnukovo

The accident with the Boeing 737-500 VQ-BPS aircraft occurred during the landing as a result of a collision of the aircraft with a snow parapet 1.1 m high at a distance of 32 m to the runway threshold (within the paved section of the runway), which resulted in damage to the main landing gear and their subsequent "folding" in the process of moving along the runway.
The accident was caused by a combination of the following factors:
- the presence of contradictions in the Federal Aviation Rules for flights in the airspace of the Russian Federation, the airline's radio control system and the aircraft operational documentation regarding the need and procedure for introducing temperature corrections to the readings of barometric altimeters at low ambient temperatures;
- Failure by the operator of the Usinsk aerodrome to comply with the FAP-262 requirements for the maintenance of the aerodrome, which resulted in the presence of snow parapets on the paved section of the landing strip;
- the operator of the Usinsk aerodrome did not eliminate the shortcomings in the winter maintenance of the aerodrome, noted based on the results of the inspection by the Rosaviatsia commission on January 22, 2020;
- lack of risk assessment in the airline associated with the execution of approaches in the baro-VNAV mode in the presence of factors that impede such approaches (low ambient temperatures, snow-covered underlying surface, drifting snow (snowstorm), significant changes in the relief in front of the runway end, lack of PAPI-type lights), as well as appropriate recommendations to the crews on the specifics of such approaches, including after the transition to visual flight, and crew training;
- insufficient assessment by the crew during the preparation of the existing threats (hazard factors) and making an insufficiently substantiated decision to perform an RNAV (GNSS) approach (under the control of the autopilot in LNAV/VNAV mode) without introducing a correction for low outside air temperature in altitude overflying waypoints, which led to a flight below the established glide path;
- performing a flight along the "extended glide path" after turning off the autopilot and switching to manual piloting without attempting to enter the set glide path;
- the PIC may have had a visual illusion of a "high glide path" due to a snow-covered underlying surface, a snowstorm and the presence of a ravine directly in front of the runway end in the absence of PAPI type lights, which led to an incorrect assessment of the aircraft's flight altitude after switching to manual piloting, lack of reaction to timely and correct warnings of the co-pilot and exit to the runway end at a height significantly less than the established one.

The aircraft overrun, destroying and damage by fire were caused by the following factors:
- repeated disregarding of the windshear warnings which when entered a horizontal windshear (changing from the head wind to tail one) at low altitude resulted in landing at distance of 1285 m from the RWY threshold (overrunning the landing zone by 385 m) with the increased IAS and tail wind;
- landing to the runway, when its normative friction coefficient was less than 0.3 that according to the regulations in force, did not allow to land.
The factors contributed the accident:
- the crew violation of the AFM and Operator's OM requirements in regards to the actions required a forecasted or actual wind shear warning;
- use of the automatic flight mode (autopilot, autothrottle) in the flight under the windshear conditions which resulted in the aircraft being unstable (excess thrust) when turning to the manual control;
- lack of prevention measures taken by the Operator when the previous cases of poor crew response to windshear warning were found;
- insufficient crew training in regards to CRM and TEM that did not allow to identify committed mistakes and/or violations in good time;
- the crew members' high psychoemotional state caused by inconsistency between the actual landing conditions and the received training as well as the psychological limit which was determined by the individual psychological constitution of each member;
- insufficient braking both in auto and manual mode during the aircraft rollout caused by the insufficient tyre-to-ground friction aiming to achieve the specified rate of braking. Most probably the insufficient tyre-to-ground friction was caused by the significant amount of water on the RWY surface;
- the aerodrome services' noncompliance of Sochi International Aerodrome Manual requirements related to the RWY after heavy showers inspection which resulted in the crew provision of wrong normative friction coefficients. In obtaining of the increased overrun speed of about ≈75 kt (≈140 km/h) the later setting of engines into reverse mode was contributed (the engines were set into reverse mode 16 s later than the aircraft landed at distance of about ≈200 m from the runway end).

The accident occurred at nighttime under foggy conditions while it was taking off after cleared by the controller due to collision with the snowplow that executed runway incursion and stopped on the runway. Most probably, the accident was caused by the combination of the following contributing factors:
- lack of guidance on loss of control over an airdrome vehicle and/or situational awareness on the airfield in pertinent documents defining the duties of airdrome service personnel (airdrome shift supervisor and vehicle drivers);
- insufficient efficiency of risk mitigation measures to prevent runway incursions in terms of airdrome peculiarilies that is two intersecling runways;
- lack of proper supervision from the airdrome service shift supervisor, alcohol detected in his organism, over the airfield operations: no report to the ATM or request to the snowplow driver as he lost visual contact with the snowplow;
- violation by the airdrome service shift supervisor of the procedure for airdrome vehicles operations, their entering the runway (RWY 2) out of operation (closed for takeoff and landing operations) without requesting and receiving clearance from the ground controller;
- violations by the medical personnel of Vnukovo AP of vehicle driver medical check requirements by performing formally (only exterior assessment) the mandatory medical check of drivers after the duty, which significantly increased the risk of drivers consuning alcohol during the duty. The measures and controls applied at Vnukovo Airport to mitigate the risk of airdrome drivers doing their duties under the influence of alcohol were not effective enough;
- no possibility for the snowplow drivers engaged in airfield operations (due to lack of pertinent equipment on the airdrome vehicles) to continuously listen to the radio exchange at the Departure Control frequency, which does not comply with the Interaction Procedure of the Airdrome Service with Vnukovo ATC Center.
- loss of situational awareness by the snowplow driver, alcohol detected in his organism, while perfonning airfield operations that led to runway incursion and stop on the runway in use.
His failure to contact the airdrome service shift supervisor or ATC controllers after situational awareness was lost;
- ineffective procedures that resulted in insufficiently trained personnel using the airfield surveillance and control subsystem A3000 of A-SMGCS at the Vnukovo ATC Center, for air traffic management;
- no recommendation in the SOP of ATM personnel of Vnukovo ATC Center on how to set up the airfield surveillance and control subsystem A3000, including activation and deactivation of the Reserved Lines and alerts (as a result, all alerts were de-activated at the departure controller and ground controller's working positions) as well as how to operate the system including attention allocation techniques during aircraft takeoff and actions to deal with the subsystem messages and alerts;
- the porting of the screen second input of the A3000 A-SMGCS at the ATC shift supervisor WP for the display of the weather information that is not envisaged by the operational manual of the airfield surveillance and control subsystem. When weather information is selected to be displayed the radar data and the light alerts (which were present during the accident takeoff) become un available for the specialist that occupies the ATC shift supervisor's working position;
- the ATC shift supervisor's decision to join the sectors at working positions of Ground and Departure Control without considering the actual level of personnel training and possibilities for them to use the information of the airfield surveillance and control system (the criteria for joining of sectors are not defined in the Job Description of ATC shift supervisor, in particular it does not take into account the technical impossibility to change settings of the airfield surveillance and control system);
- failure by the ground controller to comply with the SOPs, by not taking actions to prevent the incursion of RWY 2 that was closed for takeoff and landing operations by the vehicles though having radar information and alert on the screen of the airfield surveillance and control system;
- failure by the out of staff instructor controller and trainee controller (providing ATM under the supervision of the instructor controller) to detect two runway incursions by the snowplow on the runway in use, including after the aircrew had been cleared to take off (as the clearance was given, the runway was clear), provided there was pertinent radar information on the screen of the airfield surveillance and control subsystem and as a result failure to inform the crew about the obstacle on the runway;
- lack of recommendations at the time of the accident in the Operator's (Unijet) FOM for flight crews on actions when external threats appear (e.g. foreign objects on the runway) during the takeoff;
- the crew failing to take measures to reject takeoff as soon as the Captain mentioned «the car crossing the road». No decision to abort takeoff might have been caused by probable nonoptimal psycho-emotional status of the crew (the long wait for the departure at an unfamiliar airport and their desire to fly home as soon as possible), which might have made it difficult for them to assess the actual threat level as they noticed the snowplow after they had started the takeoff run;
- the design peculiarity of the Falcon 50EX aircraft (the nose wheel steering can only be controlled from the LH seat) resulting in necessity to transfer aircraft control at a high workload phase of the takeoff roll when the FO (seated right) performs the takeoff.

The accident with Тu-204-100В RA-64047 aircraft was caused by actuator maladjustment and reverse locking of both engines and incorrect crew actions (not complying with FOM provisions) performing landing run during spoilers and thrust reverse control that resulted in lack of efficient aircraft breaking action, RWY overrun, collision with obstacles at a high speed (~190 km/h), aircraft destruction and fatalities. (In accordance with the ICAO Accident and Incident Investigation Manual (DOC 9756 AN/965), causes and factors are in logical order, without the priority assessment).
Contributing factors to the fatal accident were:
- Actual structure stiffness of reverse control and locking mechanism unaccounted in operational documentation determining the engine control system inspection and adjustment procedure during its service replacement. This factor can emerge only in case of the crew thrust reverse control with violation of FOM provisions;
- Incoordination and conflicts in aircraft and engine operational and technical documentation and long-term formalism towards inspections of the engine control system adjustment (including reverse control and locking mechanism) by organisations performing engines replacement that didn't allow to ensure feedback with aircraft and engine designers and timely eliminate identified deficiencies;
- Unstabilized approach and significant (up to 45 km/h) rated overspeed during glide slope phase by the crew that resulted in long holding before landing, significant landing distance extension and aircraft overshoot landing (~950 m);
- Non-extension of spoilers and speed breaks in automatic mode due to the lack of the signal of simultaneous left and right struts compression caused by aircraft anticipatory "soft" landing (plunge acceleration 1.12g) at left main gear at right cross wind saturation (~11.5 м/с);
- Lack of crew monitoring for automatic extension of spoilers and speed brakes after landing and manual non-extension of spoilers;
- Violation of thrust reverse landing procedure be crew specified by FOM resulted in application of maximum thrust reverse by "one motion" without throttle intermediate stop setting (low reverse) and without reverse buckets position (stowage) monitoring that under deficiencies of the reverse control and locking mechanism resulted in immediate thrust increase;
- Lack of simultaneous main landing gear compression during the RWY motion due to design features of limit switches (no failures of limit switches were identified) of main landing gears compressed position (~5.5 tonnes leg load is required for switch actuation) and non compliance with the FOM on spoilers extension in manual mode that resulted in reverser buckets non-stowage into reversal thrust mode;
- Inadequate cockpit resource management by the PIC during flight that resulted in lack of monitoring for stabilized approach at the approach phase and in "fixation" at reverser deployment operation at the lack of monitoring for other systems operation;
- Untimely preventive measures during the investigation of the serious incident with Tu-204-100V RA-64049 aircraft operated by "Red Wings" Airlines occurred in Tolmachevo airport on December 20, 2012;
- Inadequate level of flight operation management and nonoperation of flight safety control system in the airline and formal attitude of the pilot-instructor towards proficiency check of the PIC and the lack of the appropriate supervision over proficiency checks and flight operations using flight recorders that didn't allow to timely identify and eliminate regular deficiencies in PIC's piloting technique regarding increased speed holding during glide-slope flight and the procedure of using reverse thrust application at landing run operation as well. Supervision over proficiency checks specified by FAR-128 (clause 5.7) wasn't held;
- Lack of actions training in situations connected with failure of main landing gears limit switches in line proficiency check programs of crew members followed by non-extension of spoilers and speed breaks in manual mode. Technical abilities of the available simulators don't allow to train this situation.