Accident Antonov An-26KPA RA-26673,

ASN Wikibase Occurrence # 318935

Date:	Wednesday 22 September 2021
Time:	18:11
Type:	Antonov An-26KPA
Owner/operator:	LPS Flight Checks & Systems
Registration:	RA-26673
MSN:	8408
Year of manufacture:	1979
Total airframe hrs:	36881 hours
Engine model:	Ivchenko AI-24VT
Fatalities:	Fatalities: 6 / Occupants: 6
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	40 km SW of Khabarovsk - Russia
Phase:	En route
Nature:	Calibration/Inspection
Departure airport:	Khabarovsk-Novy Airport (KHV/UHHH)
Destination airport:	Khabarovsk-Novy Airport (KHV/UHHH)
Investigating agency:	MAK
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
An Antonov An-26 of LPS Flight Checks & Systems was destroyed after impacting a mountainside 38 km from Khabarovsk, Russia. All six on board were killed.
The aircraft operated on a navaid calibration flight for runway 05R at Khabarovsk-Novy Airport. One of the tasks of the mission was to measure the range of the ILS localizer. For this task the aircraft was to fly the reverse of the runway 05R approach course with a lateral deviation of at least 10 km and continue to a distance of 36 km.
After an approach the flight crew was instructed to climb to an altitude of 600 m and turn to follow the reverse approach course.
However, the published minima for that sector up to a distance of 46 km is 1200 m.
During the flight at an altitude of about 600 m on autopilot with a course of 220-230°, the aircraft collided with the wooded slope of Khrebtovaya Mountain (793m / 2602ft asl). The flight crew had initiated a climb three seconds before the impact at an elevation of 742 m.

Conclusion:
The cause of the accident with the aircraft An-26 RA-26673 was that it was flying over the radio beacons of runway 05R of Khabarovsk (Novy) airfield in instrumental weather conditions at an altitude of 600 m QFE, which is significantly lower than the established minimum safe altitude (1200 m QFE) in the sector where the accident occurred, which led to a collision with the mountain slope in controlled flight.

The most likely contributing factors were:
- Lack of current regulatory documents governing the conduct of flight inspections of ground-based flight support equipment, avionics, and civil aviation lighting equipment systems, including for airfields whose topographical features do not allow inspections to be conducted according to standard procedure;
- unreasonable establishment of a continuous exclusion zone from 0 m to 6000 m by altitude within a radius of 99900 m from KTA for the function of signaling aircraft descent below the minimum safe altitude (MSAW), which excluded issuing a corresponding warning to a DPC dispatcher;
- absence of the ATC Dispatcher's Work Procedure at the ATC and other documents of the ATC of EU ATS (Khabarovsk):
o procedure for ATC specialists when flying over the aerodrome's RMS;
o procedure for practical training of ATC specialist performing direct ATC under the control of ATC instructor, including their interaction and responsibility for ensuring flight safety.
- making a decision to combine two sections of trainee navigator training without the necessary risk analysis and risk mitigation measures;
- insufficient preliminary preparation of the crew for the overflight, including failure to take into account the terrain features (presence of zones with considerable elevation) and geographical features (proximity to the state border) of the airfield, as well as the presence in the crew of a trainee navigator not admitted to independent flights and to this particular type of work;
- insufficient cooperation between the crew and ATC specialists when preparing and performing the overflight, including coordination by the crew and ATC specialists during the flight of the maneuver with violation of the established minimum safe altitude when performing a flight under instrumental weather conditions;
- interference of the instructor navigator in the flight procedure (route change) without assessing the relevant risks in the absence of the pilot's control;
- failure of the trainee navigator to comply with the operating procedures in terms of comprehensive use of aircraft equipment for precise piloting, maintenance of safe altitudes and timely informing the crew about turns, as well as lack of proper control over his actions on the part of the instructor navigator;
- lack of control over the aircraft flight by the trainee controller and instructor controller at their minimum workload (controlling only the aircraft which had suffered a crash).
The Operator's Flight Operations Manual lacked standard operating procedures for crew operation with the EGPWS Mark VIII early ground collision warning system installed on the aircraft during overflights. There were no warnings (triggering) of this system during the flight. Probably, the system was not activated by the crew in order to avoid its frequent activation during the flight. Due to complete destruction of the system as a result of the crash, it was impossible to determine the causes of its failure.
Proper use of the system could have prevented the accident.

Accident investigation: