On 16 May 2019, an Ilyushin Il76 (EP-PUS) being operated by Pouya Air on a non-scheduled international cargo flight from Tehran Mehrabad to Yerevan as YA2395 overran the temporarily reduced available landing distance at destination after making an ILS approach in day VMC. No significant obstructions were encountered during the overrun and the aircraft sustained only minor tyre damage caused when it ran over and destroyed one of the runway end lights.
An Investigation was carried out by the Aircraft Accident Investigation Board (AAIB) of the Iran Civil Aviation Organisation (CAO) after delegation from the Armenian Civil Aviation Committee on behalf of the State of Occurrence. The FDR was removed from the aircraft and data relevant to the event were downloaded but the CVR was found not to have been isolated after the event and relevant data from it was therefore overwritten.
It was noted that the 51 year-old Captain, who had been PF for the flight, had a total of 7,800 flying hours which included 3,210 hours on type. The 55 year-old First Officer had a total of 4,955 flying hours which included 3,000 hours on type.
It was established that prior to boarding the aircraft for the flight to Yerevan, both pilots attended a briefing in the airline’s Dispatch Office and received from the Dispatcher the flight document folder and a specific briefing about the Yerevan landing distance NOTAM which included reference to a reduction in the landing distance for both directions of the runway there from the normal 3,850 metres to 2,400 metres.
The subsequent flight proceeded normally until within Armenian airspace and nearing Yerevan. The Yerevan ACC controller advised the flight that radar vectoring to an ILS approach to runway 09 could be expected and after transfer to APP Radar, the flight was “informed of the displacement of the runway 27 threshold by 1,450 metres”. As previously advised, radar vectors to the 09 ILS followed and the flight was subsequently transferred to TWR where it was cleared to land at 6nm from touchdown with a spot wind of 190°/4 knots. Shortly after this, TWR added that the flight should expect to exit the runway at intersection ‘B’ after landing. NB: Exit ‘B’ is 2,300 metres from the landing threshold of runway 09.
The landing was made by the Captain “with the assumption of a 3,850 metre LDA” being available and he therefore did not take any action to ensure that the aircraft would be able to stop within the actually-available 2,400 metre LDA. As a consequence he “suddenly encountered a row of elevated lights across the runway” when it was too late to stop without an overrun. He decided “in the spite of existence of obstacles, to continue without immediate braking to avoid sustaining of damage to landing gear”. The aircraft subsequently collided with one of the elevated lights as it departed the end of the designated runway length and the TWR controller instructed the aircraft to stop which was acknowledged and complied with without any further obstacles being encountered. No explanation was advanced as to why the ATC advice given to the crew whilst on finals and acknowledged to expect to exit the runway at intersection ‘B’ (which was 100 metres before the end of the declared LDA) was not followed.
It was found that according to the QRH, at the prevailing aircraft ELW of 151 tonnes, the landing distance required on a dry runway using 43° flap and full reverse thrust was 2,100 metres.
The Context for the Excursion
Two NOTAMs relevant to the event were extant prior to the departure of the flight from Teheran, with their period of validity having commenced at 0500 the day prior to the overrun. The one advising of the temporary reduction in runway length, to which the flight crew were alerted at Dispatch, was A0058/19. It included approval for aircraft landing on runway 09 to make a 180° turn after completing a landing if necessary (the 2,400 metre runway length exceeding the available turn off at exit ‘B by 100 metres). A second related NOTAM - A0060/19 - effective from the same time and further advised in relation to the reduction on runway length that the 09 ILS would be out of service with only non precision LNAV approaches to that runway available.
The Investigation noted that according to ICAO Annex 14 Attachment ‘A’, “a displaced threshold affects only the LDA for approaches made to that threshold; all declared distances for operations in the reciprocal direction are unaffected" and on that basis concluded that advice of the similar reduction in the 09 LDA should have been explicit in the first NOTAM.
The fact that two NOTAMs were issued about a series of changes all related to the reduction in the normally-available runway length was noted to contradict remarks contained in ICAO PAN-AIM (Doc10066) that "each NOTAM shall be as brief as possible and so compiled that its meaning is clear without the need to refer to another document”.
The absence of any NOTAM information describing the installation of elevated red lights to mark the end of the reduced length runway 09 was also noted to be contrary to the corresponding guidance contained in the ICAO Aeronautical Information Services Manual (Doc 8126) which stated that NOTAM issue is required to notify the "interruption of or return to operation of major components of aerodrome lighting systems".
The Findings of the Investigation included, but were not limited to, the inadequate Dispatch briefing, the flight crew’s failure to properly review the briefing information provided by Dispatch, the inadequacy of the NOTAM information issued concerning the reduction in runway length and the provision of an ILS approach by ATC when this had been officially notified as unavailable.
The Investigation formally determined that the Cause of the Serious Incident was "the wrong perception of the flight crew regarding the content of the NOTAMs issued in respect of the displaced threshold of runway 27 at Yerevan”.
Three Contributory Factors were also identified:
- Insufficient risk assessment by the airline in respect of the NOTAMS issued for the destination airport.
- Lack of supportive information from the destination airport operator about the issued NOTAM on reduced runway length.
- Ineffective flight crew training in respect of NOTAMs and their potential relevance to the arrival briefing.
Six Safety Recommendations were made as a result of the Investigation as follows:
- that the Iran Civil Aviation Organisation (CAO) ensure that risk assessment of new routes for non scheduled flights are kept/focused on airline operations manuals.
- that the Iran Civil Aviation Organisation (CAO) require all operators to accomplish arrival landing distance assessments before every landing based on a standardised methodology involving the use of approved performance data, actual arrival conditions and a means of correlating these with the braking ability of the aircraft.
- that the Iran Civil Aviation Organisation (CAO) review airline training programs and manuals to ensure they incorporate the revised guidelines concerning ‘Runway Overrun Prevention’.
- that the General Civil Aviation Authority of Armenia consider the findings of this report and ensure implementation of ICAO Annex 15 standards for NOTAM issue in order to improve levels of safety at airports in the territory of Armenia.
- that Pouya Air review flight crew training programs and manuals to ensure training in landing on displaced runway thresholds covers (1) Dispatch Briefing; (2) take off / Landing distance (3) Engine reverser / Brake limitation.
- that Pouya Air revise the arrival / landing check list for flight crew to include confirmation / review of the condition of planned landing runway(s).
The Final Report of the Investigation was issued on 10 July 2019 and subsequently made available online.