Airport (less than 10 km from airport)

On final approach, the right engine lost power, causing the aircraft to stall because the speed dropped. Investigations were unable to determine the exact cause of the loss of power because the aircraft was totally destroyed. Nevertheless, the crew was unable to expect a stall recovery because the stall occurred at an insufficient height.

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 pilot's loss of airplane control while attempting to fly a missed approach procedure in instrument meteorological conditions.

The accident was the consequence of the combination of human and technical factor. During the approach to land, the crew observed a fluctuation in oil pressure in the instrument panel of the #2 (right) engine. After landing, the crew activated the thrust reversers on both engines without waiting for the Beta light, an essential indication to ensure a proper operation of those system. This configuration caused the aircraft to turn sharply to the left at an angle of 45° because the thrust reverser system activated on the left engine only. The fluctuation in the oil pressure observed by the crew on final approach and the malfunction of the right engine was the consequence of an oil leak in flight.

Findings as to causes and contributing factors:
1. During the extension of the landing gear, a wire bundle became entangled around the landing-gear rotating torque shaft, preventing full extension of the landing gear.
2. The entanglement by the wire bundle also prevented the alternate landing-gear extension system from working. The crew was required to conduct a landing with only the nose gear partially extended.
Other findings:
1. The wire bundle consisted of wiring for the generator control circuits, and when damaged, disabled both generators. The battery became the only source of electrical power until the aircraft landed.

The pilot's failure to properly configure the rudder trim for takeoff and his failure to maintain directional control during a precautionary landing, which resulted in a runway excursion and collision with terrain.

The pilot's failure to maintain sufficient clearance from trees during the single engine and landing approach. Contributing to the accident was the loss of power in the left engine due to an improperly installed rubber boot that became dislodged and was then partially sucked into the fuel injector servo, which caused an excessively rich fuel-air mixture that would not support combustion.