UIA B738 at Tehran on Jan 8th 2020, lost height after departure, aircraft shot down by Iran's armed forces

Last Update: March 17, 2021 / 16:41:41 GMT/Zulu time

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Incident Facts

Date of incident
Jan 8, 2020

Classification
Crash

Aircraft Registration
UR-PSR

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

On Mar 17th 2021 Iran's CAO released their final report and attachments (alternate via AVH final report and Attachments) in both Persian and English, the English version of the final report starting on page 141 of the PDF, concluding the probable causes of the crash were:

Cause of the Accident

The air defense’s launching two surface-to-air missiles at the flight PS752, UR-PSR aircraft, the detonation of the first missile warhead in proximity of the aircraft caused damage to the aircraft systems, and the intensification of damage led the aircraft to crash into the ground and explode instantly.

Other Contributing Factors

- The mitigating measures and defense layers in risk management proved to be ineffective due to the occurrence of an unanticipated error in threat identifications, and ultimately failed to protect the flight safety against the threats caused by the alertness of defense forces.

In addition to the facts reported in the preliminary report the CAO states:

Every State has complete and exclusive sovereignty over the airspace above its territory5, and no aircraft may be operated over an airspace except with the permission of the State managing that airspace. Each State has the authority to limit the operation over the airspace managed by them.

On the other hand, the States have oversight on the safety of airlines for which they have issued certificates and may impose restrictions on their activities in accordance with the laws and regulations they enact.

Further, airlines are inherently responsible for the safety of their operation and shall ensure the safety of the routes in which they conduct flights.

One of the factors potentially hazardous to flight safety is military activities. Therefore, the States managing the airspace, the ones that have oversight on the airline activities as well as the airlines themselves shall gather information related to military activity hazards, conduct relevant risk assessment and adopt mitigating measures to maintain the associated risk within acceptable levels.

As can be seen in Figure 42, the State managing the airspace may impose restrictions over its own airspace, which can include the prohibition on entry into certain geographical areas, limitations on some routes, flight altitude and some of the normal procedures.

Naturally, the State can impose restrictions on the operations of operators certified by them, beyond those done by the State managing the airspace.

The airline shall comply with the restrictions imposed by the State managing the airspace and those of the one that has certified their operation. However, they may consider more operation-related restrictions in that airspace in order to ensure their desired level of safety.

...

Iran Airspace Risk Assessment at the Time of the Accident

Prevailing Conditions

When Major General Qassem Soleimani, one of the top commanders of the Armed Forces of the Islamic Republic of Iran, was on an official trip to Iraq, he was targeted at Baghdad airport in a U.S. drone strike on January 3, 2020, where he and a number of his entourage, including a senior commander of the Iraqi counter terrorism force, lost their lives.

The United States claimed responsibility for the operation. The Iraqi government announced the operation had been carried out without their permission or knowledge.

Iran strongly condemned the assassination and officially declared it a clear example of state terrorism, the responsibility for the consequences of which would rest entirely with the U.S. regime. Iranian officials also vowed they would exact revenge on the U.S. action appropriately.

In the morning of Wednesday, Jan. 08, 2020, at 02:00, in response to the U.S. action, the Armed Forces of the Islamic Republic of Iran started a missile attack on the Al Assad base in Iraq, where the U.S. forces were based; the attack was ended in at 02:05.

Considering the possibility of the conflict escalation through the American counterattack by its military forces in the region, the relevant defensive units, including the air defense sector was placed on a higher level of alertness.

Risk Assessment and Planned Measures

The accident investigation team was provided with information on the measures taken by the military sector.

The investigation team realized that although different and specific definitions, techniques, tools, forms and diagrams are used for risk management in the military sector, they are substantially consistent with the aviation risk management literature.

The identification of Generic Hazards, the determination of Specific Hazards, and the type of operations combinable with hazards are among the components used in the military sector.

The investigation team reviewed the documents and records related to the risk management method in the military sector and given the complexity of these part of evidence, the key aspects and outcomes are described in a coherent manner with conventional risk management literature.

In a situation where the possibility of military move against Iran and its interests was growing, the players whose activity or readiness was potentially hazardous to civil aviation were taken into account along with their intentions.

The unintentional targeting was classified into two general probabilities:

- Misidentification: When a commercial aircraft could be identified and targeted as a hostile target.

- Accidental strike (Mistargeting): When during a conflict with a hostile target, a commercial aircraft is damaged as a result of military actions related to the conflict with another target.

Due to the very high sensitivity of commercial flights in the event of a conflict, it was decided in case of an air attack, all commercial flights, including transit flights in addition to the inbound and outbound ones to Iran’s airports, would be stopped. Then, depending on the severity and location of the conflict, a decision should be made and announced regarding the continuation of the aircraft operation. Nevertheless, given that in the event of a conflict, it would not have been possible to immediately stop the aircraft already on their flight paths, the routes more likely to interfere with the enemy military operations in that situation would be gradually cleared of air traffic independently and with no regard to the conflict initiation, with no new flights being directed to these routes.

The three parties below were considered to have had the possibility to perform military activity in Iran’s airspace:

- Iranian defense forces
- Possible attacking forces
- Terrorist groups

Terrorist groups have a history of intervention in aviation in Iran, which was limited to hijacking. According to the collected information, the probability of their attack on passenger aircraft was considered quite low considering the extent of their ability and presence in Iran, not to mention the equipment available to them.

Regarding the possible attacking forces, two dimensions, namely intention and type of commercial aircraft operation were analyzed.

According to the analysis, the probability of an intentional attack on commercial aircraft by foreign forces was determined to be low, but the unintentional damage to commercial aircraft was considered probable due to misidentification or mistargeting in the event of a conflict.

Commercial aircraft departing from joint civil-military airports would be at higher risk of misidentification and mistargeting by enemy, and the risk of being misidentified by commercial aircraft departing from commercial airports had been determined to be lower. In order to minimize the risk of misidentification by defense forces, it was decided to identify and track all commercial flights from the beginning so that in the event of a conflict, the military forces would be able to take immediate action thanks to their full knowing of directing flights to safe areas.

In addition, the probability of the attack to joint civil-military airports was considered very high in case of an attack to Iran’s airports, and the probability of attack to civil airports was determined low. The probability of attack to IKA was assessed as very low.

The risk of accidental targeting of aircraft entering Iraq from Iran was assessed as high, and the probability of accidental damage to transit aircraft in the area between Iran and Iraq border could not be ruled out.

It was impossible to reduce the risk of targeting the commercial aircraft crossing the Iran and Iraq border to an acceptable level; hence it was necessary to stop the traffic exchange between airspace control centers of Iran and Iraq.

In the event of a conflict, Iran’s western airspace was deemed unsafe and therefore it was necessary to stop flights from four parallel routes in the west of Tehran FIR. Given that in the event of a conflict, there would not have been enough time to clear and direct the aircraft of such routes to the safe ones, the gradual evacuation of routes from transit flights and denying clearance for new traffics in these routes was considered as a preventive measure.

...

At the time of the accident, the CMOCC had notified the three following preventive measures to the Tehran ACC chief on duty during an urgent coordination meeting minutes after attack to Al Asad base:

1- The evacuation of four parallel routes in the west of the country

2- The ban on traffic exchange between Tehran and Baghdad FIR

3- Coordination with the air defense sector prior to issuing a startup approval for departure flights.

...

Investigations showed that the measures adopted had been notified to the civil sector based on the planned schedule.

As for PS752, according to the prevailing conditions, the plan was to notify the flight specifications to the defense sector and make coordination with them before issuing clearance for engine startup.

Review of evidence regarding flight PS752 showed that the plan had been implemented and the air traffic control had issued the clearance for engine startup after making coordination with the air defense sector.

Also, the flight PS752 plan had been sent to the military sector, and the CMOCC had been receiving the civil surveillance radar information including the very flight specifications. Considering the location and time of the PS752 takeoff as well as its trajectory to leave Iran FIR, which was not in the limited areas in west of FIR (Figure 48), the measures envisaged in the risk reduction program from this perspective had also been implemented according to the plan.

...

For evacuation of routes, at the first the inbound flights were routed to other routes operationally. Considering the rise in the workload together with the conditions persistence, NOTAM No. A0087/20 (Figure 51) was issued hours after the accident at 10:27 on Jan. 08, 2020, whereby new air traffic route scheme was announced.

...

It was also observed that at 04:11 Iraq ACC requested their counterpart in Iran to accept the entry of British Airways fight BAW124 into the Iranian airspace. This was, however, denied due to the restriction imposed on the traffic exchange between the two countries -Iran and Iraq. Such a negative response was in line with the planned preventive measures.

...

Risk Management in the Airline and the State of the Operators

According to the information provided by the Ukraine International Airlines, "the safety risk assessment is carried out by UIA airlines in compliance with the Law of Ukraine On the State Aviation Security Program of Civil Aviation” of March 21, 2017.

The risk assessment in UIA is in accordance with the Annexes to ICAO Chicago Convention: Annex 17 “Security” and Annex 19 “Safety Management” ICAO Doc 8973 “Aviation Security Manual”, ICAO Doc 10084 “Risk Assessment Manual for Civil Aircraft Operations Over or Near Conflict Zones”, ICAO Doc 10108 “Aviation Security Global Risk Context Statement” and IATA “Operational Safety Audit Standards Manual.

UAI airlines had performed the assessment of the safety risk assessment for the flight PS 752 on the ground of the following analysis of the information.

There had been requested NOTAMs of the whole route, and, in particular, those ones from the Civil Aviation Authority of Iran, from the State Aviation Service of Ukraine, as well as from the civil aviation authorities of the countries through which the respected route had been scheduled (OIIE PARO2L PAROT UL125 BUDED UR660 ERZ UL851 KUGOS M860 DIGAM ETNIL M435 MIMKO T219 KONIP B246 CY CY1F UKBB), Conflict Zones Information Bulletin (CZIB’s) published on EASA web-site10 had been analyzed, the information related to the respected region risk assessment, which was placed on the site11 of the State Aviation Service of Ukraine, had been reviewed , there had been considered the world map of risk zones on the web site .

UIA believes that any information having been promulgated by 07.01.20 and the morning of 08.01.2020 did not indicate a presence of threats for PS752 civil fight safety, which was performed by the aircraft with Ukrainian registration from Tehran civil airport being completely opened for civil aviation flights and it did not contain any limitations or warnings as for the opportunity of such a flight performance.

There did not exist any prohibitions and limitations for the use of Iran’s airspace en route of PS 752 flight imposed by any governmental and/or international organizations, being competent to introduce such prohibitions. Besides that, there had not been sent any warnings or specific flight performance conditions by the ATS, from military bodies, from airport Imam Khomeini (or the Ukraine’s authorities) to the Airlines or to the air crew of PS 752 flight.

Other air carriers, including Iranian and foreign ones, had performed
flights on the same day to/from Imam Khomeini airport till PS752
accident."

The operation of UIA showed that no restriction had been imposed on operation of flight PS752 from UIA or State of Ukraine.

One of the sources that could have helped the understanding of the status of the crew's perception of the conditions and possible decision-making about restrictions or measures at operational level was the conversations of the flight crew inside the cockpit. Standard operating procedures at UIA did not require the crew to manually turn on the CVR before engine start and the voices related to the briefing time before takeoff and cabin check and preparation were not recorded. The voices recorded afterwards did not indicate any condition of the airspace, concerns and possible precaution or a decision-making related to the condition.

The investigation activities shows that no other airlines who had departure flight from IKA in the day of accident, imposed restrictions on their operation on the basis of the flight route safety risk assessment results

The availability of Information and the Level of Access to Them

The provision of adequate and timely information is essential for the proper performance of the responsibilities of the various parties in managing the risk of operations in an airspace from the perspective of potentially hazardous military activities.

Although States use overt and classified information to assess the situation, when the situation is changing rapidly, the timely dissemination of information plays an important role in assisting different parties in taking the necessary measures.

The news on the missile attack on Al Asad airbase on Jan.08, 2020 was
publicly announced after a few minutes following the attack.

In an official statement released in the very hours , the U.S. Department of Defense confirmed the attack to the American Forces in Iraq and announced, “It is clear that these missiles were launched from Iran.”

The news of this statement was also published in the mass media. It could be accessed at least at 03:11 on January 08,13.

The Islamic Republic of Iran Armed Forces released an official statement regarding the missile operation, which was covered by Iranian news agencies14 at around 02:40 on January 08, 2020 Tehran time and published in the international mass media shortly.

At 03:15 on the 8th of January, the Federal Aviation Administration (FAA)
of the U.S. issued the following NOTAM number A0001/20 prohibiting
conducting flights in Baghdad FIR for the persons and operators already
described under its oversight:

A0001/20 NOTAMN

Q) KICZ/QRDLP/IV/NBO/AE/000/999/

A) KICZ

B) 2001072345

C) PERM

E) SECURITY..UNITED STATES OF AMERICA PROHIBITION AGAINST CERTAIN FLIGHTS IN THE BAGHDAD FLIGHT INFORMATION REGION (FIR) (ORBB). THOSE PERSONS DESCRIBED IN PARAGRAPH A (APPLICABLITY) BELOW ARE PROHIBITED FROM OPERATING IN THE BAGHDAD FLIGHT INFORMATION REGION (FIR) (ORBS) DUE TO HEIGHTENED MILITARY ACTIVITIES AND INCREASED POLITICAL TENSIONS IN THE MIDDLE EAST, WHICH PRESENT AN INADVERTENT RISK TO U.S. CIVIL AVIATION OPERATIONS DUE TO THE POTENTIAL FOR MISCALCULATION OR MIS-IDENTIFICATION.

A. APPLICABILITY. THIS NOTAM APPLIES TO: ALL U.S. AIR CARRIERS AND COMMERCIAL OPERATORS; ALL PERSONS EXERCISING THE PRIVILAGES OF AN COMMERCIAL OPERATORS; ALL PERSONS EXERCISING THE PRIVILEGES OF AN AIRMAN CERTIFICATE ISSUED BY THE FAA, EXCEPT SUCH PERSONS OPERATING U.S.-REGISTERED AIRCRAFT FOR A FOREIGN AIR CARRIER; AND ALL OPERATORS OF AIRCRAFT REGISTERED IN THE UNITED STATES, EXCEPT WHERE THE OPERATOR OF SUCH AIRCRAFT IS A FOREIGN AIR CARRIER.

B. PERMITTED OPERATIONS. THIS NOTAM DOES NOT PROHIBIT PERSONS DESCRIBED IN PARAGRAPH A (APPLICABILITY) FROM CONDUCTING FLIGHT OPERATIONS IN THE BAGHDAD FIR (ORBB) WHEN SUCH OPERATIONS ARE AUTHORIZED EITHER BY ANOTHER AGENCY OF THE UNITED STATES GOVERNMENT WITH THE APPROVAL OF THE FAA OR BY A DEVIATION, EXEMPTION, OR OTHER AUTHORIZATION ISSUED BY THE FAA ADMINISTRATOR. OPERATORS MUST CALL THE FAA WASHINGTON OPERATIONS CENTER AT 202-267-3333 TO INITIATE COORDINATION FOR FAA AUTHORIZATION TO CONDUCT OPERATIONS. C. EMERGENCY SITUATIONS. IN AN EMERGENCY THAT REQUIRES IMMEDIATE DECISION AND ACTION FOR THE SAFETY OF THE FLIGHT, THE PILOT IN COMMAND OF AN AIRCRAFT MAY DEVIATE FROM THIS NOTAM TO THE EXTENT REQUIRED BY THAT EMERGENCY. THIS NOTAM IS AN EMERGENCY ORDER ISSUED UNDER 49 USC 40113(A), 44701(A)(5), AND 46105 C). ADDITIONAL INFORMATION IS PROVIDED AT:



F) SFC

G) UNL END

At 00:10 on the 8th of January, the Federal Aviation Administration (FAA) of the U.S. issued the following NOTAM number A0002/20 prohibiting conducting flights in Baghdad FIR for the persons and operators already described under its oversight.

A0002/20 NOTAMN

Q) KICZ/QRDLP//////

A) KICZ

B) 2001080010

C) PERM

E) SECURITY..UNITED STATES OF AMERICA PROHIBITION AGAINST CERTAIN FLIGHTS IN THE TEHRAN FLIGHT INFORMATION REGION (FIR) (01IX). THOSE PERSONS DESCRIBED IN PARAGRAPH A (APPLICABLITY) BELOW ARE PROHIBITED FROM OPERATING IN THE TEHRAN FLIGHT INFORMATION REGION (FIR) (01IX) DUE TO HEIGHTENED MILITARY ACTIVITIES AND INCREASED POLITICAL TENSIONS IN THE MIDDLE EAST, WHICH PRESENT AN INADVERTENT RISK TO U.S. CIVIL AVIATION OPERATIONS DUE TO THE POTENTIAL FOR MISCALCULATION OR MIS-IDENTIFICATION.

A. APPLICABILITY. THIS NOTAM APPLIES TO: ALL U.S. AIR CARRIERS AND COMMERCIAL OPERATORS; ALL PERSONS EXERCISING THE PRIVILEGES OF AN AIRMAN CERTIFICATE ISSUED BY THE FAA, EXCEPT SUCH PERSONS OPERATING U.S.-REGISTERED AIRCRAFT FOR A FOREIGN AIR CARRIER; AND ALL OPERATORS OF AIRCRAFT REGISTERED IN THE UNITED STATES, EXCEPT WHERE THE OPERATOR OF SUCH AIRCRAFT IS A FOREIGN AIR CARRIER.

B. PERMITTED OPERATIONS. THIS NOTAM DOES NOT PROHIBIT PERSONS DESCRIBED IN PARAGRAPH A (APPLICABILITY) FROM CONDUCTING FLIGHT OPERATIONS IN THE ABOVENAMED AREA WHEN SUCH OPERATIONS ARE AUTHORIZED EITHER BY ANOTHER AGENCY OF THE UNITED STATES GOVERNMENT OR BY A DEVIATION, EXEMPTION, OR OTHER AUTHORIZATION ISSUED BY THE FAA ADMINISTRATOR. OPERATORS MUST CALL THE FAA WASHINGTON PERATIONS ENTER AT 202-267-3333 TO INITIATE COORDINATION FOR FAA AUTHORIZATION TO CONDUCT OPERATIONS. C. EMERGENCY SITUATIONS. IN AN EMERGENCY THAT REQUIRES IMMEDIATE DECISION AND ACTION FOR THE SAFETY OF THE FLIGHT, THE PILOT IN COMMAND OF AN AIRCRAFT MAY DEVIATE FROM THIS NOTAM TO THE EXTENT REQUIRED BY THAT EMERGENCY. THIS NOTAM IS AN EMERGENCY ORDER ISSUED UNDER 49 USC 40113(A), 44701(A)(5), AND 46105(C). ADDITIONAL INFORMATION IS PROVIDED AT:

F) SFC

G) UNL

END

Further, according to the information provided by British Airways
through UK Expert, this airline had been made aware of the Iranian missile attack on the American base at 03:25 on Jan. 08, 2020, so even before receiving the formal FAA NOTAM, it had already put in place processes to stop operations entering the Baghdad and Tehran FIR, and to leave those FIRs as soon as possible if already in them, but focusing initially on the Iraqi airspace. The request of BAW124 flight for entering Tehran FIR was the result of the risk assessment at the time, but the airline was focused on securing the preference to operate through Saudi airspace.

The States’ information and actions taken by them were not necessarily limited to the above-mentioned. Nevertheless, since the investigation team had dealt with the availability of the information to the States and operators about the conditions to plan and take necessary measures, such cases are simply presented as existing examples.

The CAO listed a number of occurrences that were caused by military activities:

Korean Airlines Flight 007, Sep 1st 1983
IranAir Flight 655, Jul 3rd 1988
Siberian Airlines Flight 1812, Oct 4th 2001
Malaysian Airlines Flight 17, Jul 17th 2014
African Express 5Y-AXO, May 4th 2020

The CAO analysed:

The times provided by the military sector on the first missile launch and detonation, along with the location of the warhead fuse activation, corresponded to the time and location of the strike heard on the CVR, the termination of FDR recording and termination of the ATC transponder of the aircraft.

The investigation conducted showed that the TNT explosives found on the outer layers of the fuselage were similar to the aliphatic compounds used in the missile launched at the aircraft, and that the small amount of DNT observed could be a by-product of the thermal degradation of the aircraft conventional substances like fuel and epoxy. The DNT could be a small amount of aliphatic explosives impurities with lower quality nitrite.

The explosives found on the remaining parts of the aircraft had to do with the missile function. In fact, no explosives of an unknown origin were found in the tests and analyses.

The tests conducted on other small pieces found on the passenger seat pads revealed that none were of the missile shrapnel material, but rather the ones used in manufacturing the aircraft, and that they had spread out all across due to the explosion caused by ground impact.

Due to the termination of FDR and CVR recording before the probable time of activation of the second missile, no conclusion could be made on the effect of the second missile based on the flight recorders data.

The recorded data in ADU shows that the second missile failed and was not successful.

The video which had been recorded in a construction work area showing the missile flight and explosion supports the conclusion that the 2nd missile exploded near the aircraft.

The investigation team analyzed the last recorded position of the two missiles, which is most likely the position of the detonation. The recorded data shows that the last position of the first missile was located about 400 meters south of the aircraft track, and the last position of second missile was located about 500 meters north of the aircraft track. Since the first missile affected the aircraft, the calibration of data related to the missiles position was proven necessary. The main source of this error is the error of ADU north heading calculation, which had been determined 105 degrees. After the direction recalibration of ADU in order to align the last recorded position of the first missile to aircraft track, the locations are shifted 400 meters northward, and hence the last location of the second missile differs 900 meters from the aircraft track and in this case the missile had no chance to affect the aircraft.

Considering all the above analysis, due to the residual uncertainty of information and analysis related to second missile detonation, the proven effect of the first missile, the proven launch of second missile and the fact that for prevention of similar accidents, this information is enough, the investigation team concluded that making the conclusion about the detonation and effect of the second missile is not reliable and does not affect the outcome of this investigation.

Aircraft Technical and Operational Conditions

Aircraft technical and operational functions had been normal by the missile strike.

The technical condition and operation of the aircraft systems did not play a role in creating errors for the operator of the ADU or strengthening the context of error.

In the judicial proceedings, in a similar environment, a simulation was run to investigate how the error had been formed and how the missile was launched. All the processes in the military, civil sector, and the cooperation between them were made just as the events occurring on the day of the accident, based on the records made in all sectors using a BOEING 737 flying twice from IKA on a flight trajectory similar to that of PS752. The accident investigation team participated in the simulation to observe the events taking place in the civil and joint cooperation sectors.

Two ADUs were placed at the location of the launching ADU. The north alignment error like the launching system was repeated in one system, considered as the main one, while in the other, as the reference one, the north alignment error was corrected.

The simulation also indicated that the aircraft flight operation did not play a role in the occurrence of the error made by the air defense unit operator.

In the two times of simulation, the reference unit operators detected the aircraft from the IKA direction, while the main unit operators detected it approaching from the western area.

After the detonation of the first missile in the proximity of the aircraft, the ATC transponder and FDR recording terminated simultaneously due to damage to the aircraft. The aircraft sustained cascading damage, as a result of which, after about 16.5 seconds, the rotation frequency of one of the generators (Electrical power supply - IDG) started to decrease, causing a reduction in frequency of recorded audios in CVR and termination of recording after 2.5 seconds.

As civil aircraft are not designed and manufactured in a way to be missile resistant, the analysis of the way the missile affect the aircraft systems is pointless to safety enhancement goals. In addition to this, the severity of the damage caused by aircraft impact to the ground and the resulted explosion does not make such an analysis practicable.

CVR Turn On

The first radio communication of PS752 with the IKA ground control unit was made at 05:13:11 and recorded in the aeronautical communications systems. The CVR of the accident aircraft started recording at 05:56:18 and the flight received the clearance for engine startup and pushback at 05:55. According to the recorded voice, it can be said that the CVR was turned on automatically after the first engine was switched on.

Given the fact the flight crew had already been present at the cockpit for some time, listening to their conversations before takeoff could have helped understand if they had been made aware of Iran’s missile attack to the U.S. base in Iraq, or if they had ever talked about or made any decision regarding the conditions at the time.

The ICAO standard for the start of voice recording is set out in Annex 6 to the International Civil Aviation Convention. According to the text in Section 3.1, Part 1 of Appendix 8 (Aircraft Operations), 10th edition, Amendment 41, the CVR shall start to record prior to the aeroplane moving under its own power and record continuously until the termination of the flight when the aeroplane is no longer capable of moving under its own power. In addition, depending on the availability of electrical power, the CVR shall start to record as early as possible during the cockpit checks prior to engine start at the beginning of the flight until the cockpit checks immediately following the engine shutdown at the end of the flight.

Although the second sentence of Section 3.1 of Appendix 6 sets out the start of voice recording when the cockpit checks are performed, the condition for the existence of electrical power complicates the effective implementation of this action, making it unattended.

The civil aviation authorities have similar instructions in national regulations in this respect too, sufficing to state the same text in Annex 6. In approving the Operation Manuals of the airlines, the review of procedure related to CVR switch during cockpit checks and the clarification of the meaning of “the availability of electrical power” by the airlines are not taken very seriously either.

...

Risk Assessment by the State Managing the Airspace

As the missile attack on Al Asad base had been planned in Iran, there was enough time and information at hand to predict the situation and assess the risk for civil flights in Iranian airspace.

Due to the information classification, the risk assessment had been done before, and the mitigating measures had been planned to reduce the risk to civil aircraft.

The civil sector had been notified of such measures, which were
thoroughly performed accordingly.

Eventually, the actual risk for the “misidentification of civil aircraft departing from an international civil airport following the defense system’s initial identification” exceeded the risk level predicted, making the planned measures for this type of operation concerning the PS752 ineffective, due to the materialization of an unforeseen chain of events.

At the time, other flights had taken off form IKA, though a misidentification causing a missile launch at them never occurred.

Considering that the pattern of error making and the materialization of its consequences follow the famous patterns of the chain of events or Swiss Cheese Model, it is concluded that the presence of grounds for errors is not equivalent to the occurrence of final event. In other words, it is only in special and rare conditions that the entire chains necessary for the accident to occur are formed, while in other cases, by breaking one of the links in the chain or the effective performance of one of the anticipated defense layers, the existing latent condition would become unlikely to be materialized.

In order to realize what happened in military side, investigate the role of civil aviation operation in this event, and provide an answer into how the existing error caused an accident for this certain flight, the investigation team still submitted a request for investigating the measures and events leading to the missile launch in addition to the actions having been planned to prevent it. The military sector and the judicial authority responsible for this accident provided the information required to the investigation team accordingly.

The investigation team found that the operating military unit was not basically responsible for monitoring the targets; it was just obliged to perform the actions planned within the command hierarchy only if a target was assigned to them from the command center.

Following a tactical relocation, the relevant ADU failed to adjust the system direction out of human error, causing the operator to observe the target flying west from IKA as a target approaching Tehran from the southwest at a relatively low altitude.

The target specifications were announced to the command center, but the message was never relayed. Without receiving a go-ahead or response from the command center, he came to identify the target as a hostile one and fired missile at the aircraft against the procedure planned.

The chain of events observed by the investigation team leading to firing missile at PS752:

1 Error in North realignment of Air Defense Unit
2 Defective communication between air defense unit and coordination center
3 Wrong identification and classification of detected target
4 Failure to follow the military command procedure for missile launch by air defense unit operator

The existence of this threat and the possibility of such chains being formed had not been predicted, and had not been considered in the calculations of the risk associated with misidentification.

The chain leading to the accident demonstrates the extent to which the hazards resulting from human performance are serious with a farreaching consequence. It shows how much the ignoring the contribution and the possibility of complex combinations of rare events, could affect the accuracy and efficiency of risk management.

If normal condition with no conflicts or the possibility of that is considered at one extreme end, and on the other hand, a major military conflict at another extreme end, there would be a spectrum in between, where a series of measures must be taken to ensure the safety of civil aviation, from no operational restriction to the suspension of any civil operation depending on the very conditions.

...

During the conditions when the PS752 accident happened, the risk of commercial aircraft being accidentally struck while trying to target the hostile aircraft was estimated to have been negligible before the start of a military operation. Nonetheless, given the fact the Iranian air space is always monitored independently of a military attack, the risk of misidentification is also considered at all time, which was higher in the alertness conditions at that time.

It can finally be concluded that the risk assessment conducted was not commensurate with the real conditions at the time, and an unpredicted chain of events was materialized at the end.

The investigation team requested the authorities who had done the risk assessment to repeat the assessment considering the information gathered after the accident. The result of such assessment was similar to the previous one, and again, clearance for PS752 to conduct the flight was evaluated to be safe and coordination with air defense before startup approval was evaluated to be enough to eliminate the possibility of misidentification.

The investigation team found that in the conducted risk assessment, only the steady state of conditions had been considered. In other words, only the elements of hazards raised from the alertness of the military forces had been taken into account, but no element representing the rapid transition from one alertness level to another had been stipulated in calculations.

The investigation team identified three states for any change between the two hazard levels. The first state is the initial state of the system. After the change of condition to the next hazard level, due to the occurrence of a change in conditions which is initially unknown in terms of the extent, duration and dimensions, the system enters a transient condition. When the new condition remains stable and the elements of system, including humans get used to the new condition, the system enters into the next steady state level.

This is while entities who had conducted the risk assessment considered only the three following levels of hazards and defined and implemented the related safety measures.

The first level was the initial condition. It was predicted that after the missile attack on Al Asad airbase, the system would enter the second level, namely the alertness condition. In case of a counterattack, the conflict condition as the third level had been predicted with strict safety measures including the no-fly zone.

Transient condition is applicable to all systems. Each level of conditions has its own hazards and any change in condition includes special hazards related to the nature of change. At the time period close to the change, the change hazards must be added to hazards related to the new condition until the system enters steady state and the hazards related to change disappear.

During the investigation, some studies were done to determine the characteristics of transient condition.

The time period and level of hazards associated with transient condition are related to the range of change and the components of the system, and defining the characteristics of transient condition would not be accurate and real at this step. However, from the human factors perspective, it seems that the transient condition period must last longer than the working hours of the personnel who were working in the system at the time of transition. The personnel who work in each section of the system are less affected by the change of condition, at least in terms of situational awareness, if they start their work shift after that change, and obviously, if the change happens during their work shift, they are more affected by this change.

In PS752 accident case, taking into account that the prevailing conditions rapidly changed at about 02:00, it is likely that at the time of the accident, the transition time was not finished yet and this transient condition contributed to human errors and the existing hazards within the whole system.

The Airline’s and the State of the Operator's Risk Assessment In PS752 accident condition, it was found that some airlines had performed a risk assessments in a short period of time and implemented various measures to the point of suspension of their flight operations in some areas.

It was also found that some States quickly set and announced restrictions on the activities of airlines under their oversight.

However, some had not taken any clear action on the situation, and others had not made any assessment of the situation at a pace commensurate with that changing trend.

As for PS752, no restriction whatsoever had been imposed neither by Ukraine nor the UIA.

Figure 58 illustrates the risk assessment flowchart for the operators provided in ICAO DOC10084. The first step of assessment is collecting information, whose source could be the published aeronautical information, the special information provided to the operators by the States, special information network -where the States and operators participate-, aerodromes as well as open source information.

The collection of relevant information is a vital step in the success of risk assessment, because if the information is not available or is not collected properly and in a timely manner, the risk assessment process can not be initiated.

The speed of information collection and the vastness of its sources become far more important during the conditions like those in PS752 accident, when the changes were very rapid and in the order of few hours than when they do over a longer period of time, about a few days.

The conditions changed at such a pace and time that the exclusive sources for the provision of aviation-related information useful for the airlines did not publish any new information, but the open and public sources had released the news on the attack to Al Asad base hours before, and official authorities in the States issued statements and notifications about that event.

The investigation reveals that such information sources was not considered in the risk assessment by the operators who had departure schedule from IKA.
Incident Facts

Date of incident
Jan 8, 2020

Classification
Crash

Aircraft Registration
UR-PSR

Aircraft Type
Boeing 737-800

ICAO Type Designator
B738

This article is published under license from Avherald.com. © of text by Avherald.com.
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