ACCIDENT ANALYSIS-B-737-800-04 Sep 17- Cochin

Sequence of Events and Observations by Investigating Team

B 737-800 aircraft was involved in an occurrence on 04-09-2017 at 2112, UTC (05-09-2017 at 0242 IST) at Cochin Airport while operating Flight from Abu Dhabi to Cochin.

Captain -59 Years old, highly experienced with almost 14500 Hrs. of Flying including 4176 Hrs. on Type.

Co Pilot- 28 Years Old, Total Flying experience 1429 Hrs. and 1139 hours on B 737-800.

There were 102 passengers and 06 Crew (02 Cockpit Crew & 04 Cabin Crew) on board the aircraft.

Both PIC and Co-pilot were operating first time together for Cochin- Abu Dhabi- Cochin flight. The PIC was based at Delhi and Co-Pilot was based at Cochin by the Air India Express.

The flight took off from Abu Dhabi at 1644 UTC and landed at Cochin at 2107 UTC.

The aircraft was given landing clearance by ATC at 210324 UTC informing “landing surface wet, Runway 27 cleared to land, wind 050 degree 03 knots.”

As per METAR, at 2100 UTC the visibility was 4000 meters which reduced to 3000 meters at 2130 UTC.

ATC informed crew before landing regarding rains and runway surface as wet.

At 210715 UTC aircraft landed, and at 210741 UTC ATC informed aircraft to “vacate via convenient right”.

Since the aircraft touched runway late at approx. 4900 feet from the beginning of Runway 27 near taxiway C3 and vacated via C2 instead of usual C3 exit due to delayed touchdown.

After landing the aircraft vacated runway from C2 and was given taxi clearance to bay 23L via C-F-L and hold short of Taxiway Lima due another aircraft taxing out from bay 20.

As per CVR, while taxiing, co –pilot informed PIC about passing taxiway “E” and next is “F”.

Also, co-pilot requested PIC who was at controls, to go slow as runway markings were not visible and advised to call follow me jeep.

Co-pilot informed PIC that she cannot see any markings.

However, there was no response from PIC.

The aircraft after crossing abeam taxiway E on taxiway C made a premature left turn 90 m before Taxiway F.

Aircraft entered in Open Rain Water Drain, (3-meter-wide having depth of 1.7 meter on Taxiway side) running parallel to Taxiway “C” , situated at a shortest distance of 43.55 meters from centerline of Taxiway “C”.

PIC applied throttle three times for aircraft to come out of the drain, in spite of the fact that Co Pilot advised Captain not to do so. The aircraft didn’t come out of drain and remained stuck into the drain.

Both engines and rear belly of the aircraft became the weight bearing member and Main Landing Gear (MLG) were freely suspended in the drain.

Follow me Jeep reached at the accident site at 2117 UTC and first fire fighting vehicles reached aircraft at 2137 UTC.

Passengers were evacuated using step ladder from L1 door at 2150 UTC and last passenger deplaned at 2155 UTC.

Three (03) persons on board the aircraft received minor injuries.

There was no fire.

The aircraft received major Structural damage including damage to Nose Landing Gear (NLG), Engine inlet Cowls, Fan Cowls, Engine Strut, lower skin etc.

Findings and Recommendations by Investigation Team.

As per PIC’s statement, he reached hotel late in the previous night while operating flight Cochin- Dubai-Cochin and was not able to sleep before the flight and was fatigued at the time of landing at Cochin. In CVR, there is noise of PIC yawning in the flight.

He also mentioned that Fatigue, poor weather and confusing taxi track appearance contributed to incorrect judgment of initiating the turn short of the link “F”.

As per co-pilot’s statement, when PIC turned aircraft left prematurely, she was adjusting her wipers and spectacles to see clearly.

PIC was found BA +ve on 17.08.2007 and 09.01.2016.The license of PIC was suspended by DGCA for 3 Months from 09.01.2016.

The Tower Controller was handling three aircraft at the time of the accident and fourth joined after five minutes.

The tower controller failed to maintain two way eye contact i.e. surveillance over the subject aircraft and lost situational awareness.

There was blatant use of Non Standard ICAO language as well as Non Standard Phraseology and local language among invariably all the Units i.e. Tower, Approach, Area, SMC, Alpha, CIAL Tower Coordinator in Tower, Operational Vehicles etc.

WSO was on ATC Channel till 2125 UTC and made a logbook entry regarding the accident at the same time i.e. 2125 UTC and didn’t reach the tower till 2130 UTC.

As per Alpha’s statement, WSO was in Tower. But after corroboration from ATC log books and ATC tape transcripts, it was found that WSO was on Channel at ASR till 2125 and at the same time i.e. 2125, WSO made a detailed log in WSO’s log book about the accident.

It means WSO has not reached Tower before 2140 and by this time, the Controller had briefed the relieving Controller and handed over watch at time 2130 UTC.

The markings at Taxiway C were repainted in March 2017 and Markings on Taxiway F were repainted in July 2017.

However as per CVR tape transcript, the taxiway marking were not visible.

 The DGCA team also found on 05-09-2017 that Taxiway C Centerline Marking was not visible.

 As per records submitted by ATC, a few other aircraft also reported that Taxiway Marking were barely visible during the month of April, May and June 2017.

The Taxiway C was equipped with blue Taxi way edge lights. Alternate Taxiway C blue lights and Taxiway Sign Board lights were on at the time of accident.

 However, there were no Taxiway center lights.


Taxiway edge lights are spaced 60 feet apart. At the time of taxiing, one circuit of taxi lights was working and alternate blue lights was glowing.

CCTV camera recordings shows that the taxiway blue lights were ON and Green leading lights to the taxi track link (Taxiway F) were ON with Low intensity when aircraft was taxiing.

After the accident the intensity of Green leading lights was increased by ATC.

Cochin Airport is equipped with CAT-I Approach CAT I lighting system.

Alternate Taxiway C blue lights were “ON” at the time of accident. There was no request received from crew to ATC to switch “ON” all Taxiway lights or increase the intensity of the lights.

Taxiway sign lights were on at the time of accident.

The Retro reflective Markers / Delineation Markers were not installed at drains at Cochin.

Taxiway Edge Lights — “Sea Of Blue” Effect

As per ICAO the Aerodrome Design Manual (Part IV) para 9.2, the concentration of taxiway edge lights in the operational area often results in a confusing mass of blue lights commonly referred to as a “sea of blue”.

In some cases, this can result in pilots finding it difficult to correctly identify the taxiway boundaries.

This problem particularly occurs in complex taxiway layouts with small radius curves.

This problem can be removed by the use of taxiway center line lights, thereby eliminating the need to install edge lights in much of the taxiway system.

Edge lights are normally still installed on curved portions of taxiways, at taxiway intersections and at taxiway/runway intersections.

At Cochin Airport when the aircraft moved forward from the eastern end of the taxiway towards exit F, the pilots must’ve been seeing clearly the taxiway stretching ahead.

The thick yellow line marking and the center-line of the taxiway too must’ve been visible, due to the edge lighting.

A little farther ahead on the right, there were five links-taxiways perpendicular to the taxiway that connect the taxiway with aprons.

These links -denoted by Roman alphabets G, F, E, B & A- too had blue edge lights.

When any aircraft initiates the 90 degree turn to enter the link-taxiway, the glow of the blue lights fitted along the edges of the five parallel exit paths can together appear as a huge, rectangular illuminated surface. This optical illusion is the Sea of Blue Effect.

It occurs because blue light that travels as shorter, smaller waves gets scattered more than other colors.

The light thus scattered from the edges of the five link-taxiways spaced just 125m apart can easily overlap, hiding the open land between them. So the chances are abundant for the pilot either to totally miss the actual exit that got submerged in the ‘blue sea’ or to confuse between the exit (link-taxiway) and the area between the link-taxiways.

In rains & night, the concentration of taxiway edge lights called “sea of blue” may result causing the pilot either to miss the actual exit that got submerged in the ‘blue sea’ or to confuse between the exit (link-taxiway) and the area between the link-taxiways.

As it was raining, there are chances that the pilot may have been influenced by “blue sea effect” resulting in missing the actual exit.


The accident occurred at 2112 UTC (0242 IST) which is in the window of circadian low (WOCL) cycle

RVR equipment/ SMR-Not installed at Cochin Airport.

The drains may be properly illuminated and the obstructions to be indicated.

CIAL may also explore the possibility of installing the center line lights for taxiway C for better visibility.


Analysis by Aviation Safety Management Society of India-Lessons Learnt

Main Cause of Accident.

In the considered opinion of ASMSI professionals, this accident occurred due to poor CRM and Fatigue factor of the Captain.

Contributory Factors.

  • Adverse Weather, Wet Runway Conditions, in addition to the existence of only alternate Taxi lights on low intensity resulted into poor visibility conditions and inability of the pilots to see clearly, the Taxi center Line and other Markings.
  • Operation during Window of Circadian Low.
  • Sea of Blue Effect.
  • Absence of any light markings to caution the pilots about the presence of the drain.
  • Possibly, complacency on the part of the Captain leading to loss of situational awareness.

The Inquiry team seem to have not deliberated enough on the point as to why a highly qualified and experienced Captain, turned 90 meters before the turning towards foxtrot Taxi Track, without confirming the correct place to turn. It can only happen if the pilot is fatigued, stressed and under tension due to fear of loss of professional reputation.

No questions seem to have been asked to the captain, as to why he failed to respond, to the cautions by the Co Pilot, when she repeatedly told the Captain that visibility is poor and she is unable to see the Taxi Track markings and advised the Captain to go slow and ask for Follow Me Jeep.

It is indeed intriguing that the Captain opened throttle three times in spite of the caution by Co Pilot, to move his aircraft forward when the aircraft was on its belly in the drain. The complete perspective of the Captain and Co Pilot related to the ground from the cockpit, would have changed, when the aircraft came to rest, on its engines and belly. How come the pilots did not realise this major change in perspective.

The touchdown of the aircraft 4900 feet, after the beginning of the Runway, goes to show that the pilot was fatigued, due to which he was not situationally aware. The failure of the pilot to respond to the cautions by the Co Pilot, also points to either the arrogance of the Captain by virtue of large Power Distance or uncertain, confused and fatigued state of mind.


CRM -Power Distance.

  1. There appeared to be serious lack of CRM (communication, leadership, team work and synergy) between Captain and Co Pilot.
  2. There was vast gap between the Age (Capt. 59 Years, Co Pilot 28 Years, Experience (Capt. 14500 Hrs, Co Pilot 1500 Hrs) and Status (Capt. Very Senior Commander, Co Pilot Very Junior) of the Pilots. Thus, there was large Power Distance between Captain and Co Pilot by virtue of the vast difference in the age, experience and status.
  3. The large power distance takes away the ability of the Co Pilot to Speak up, give flight and safety related inputs to the Captain, to advise the Captain if he is going wrong or committing errors and to be assertive.
  4. Crew pairing is an important part of CRM. The Captain and Co Pilot were flying together for the first time and the large Power distance between the Pilots played a major role towards causation of this serious occurrence. In addition, Male and Female Crew composition can lead to lack of synergy which may affect the safety of the flight.
  5. Although in this accident, Co Pilot appeared to be alert and kept advising the captain correctly but the Capt. failed to pay any heed to the Co Pilot due to, may be his ego, overconfidence, arrogance and complacency which unfortunately comes in most Pilots with age, experience, seniority and status(Power Distance).
  6. Due to Power Distance, the Co Pilot was not assertive enough for which, of course, she can’t be blamed since majority of Co Pilots are not able to speak up to the Captain which is a shortcoming in the CRM Training, with consequent compromise on Safety.
  7. The Captain ignored the inputs from the Co Pilot where she clearly stated repeatedly that please Taxi slowly since she is not able to see the center line markings, advised the Captain to ask for Follow Me Jeep and not to  open throttle when the pilot was trying to take out the aircraft from the drain. It appears that the Pilot was not aware that the aircraft was in the drain.

Fatigue Factor

  1. As per the statement of the Captain, he had not slept well and was obviously sleepy (yawning in the Cockpit).Long flight in the night, adverse weather and operations during WOCL added to the fatigue factor of the Captain, particularly since he was already suffering from lack of sleep. Fatigue leads to increased reaction time, reduced attentiveness, impaired memory and withdrawn mood. The very late touchdown i.e. 4900 ft. ahead from the beginning of the runway, lack of response to the inputs from the Co Pilot, turning 90 Meters before the correct turning point, failure to realise that the aircraft has got into the drain and opening throttle to move the aircraft forward three times shows that the Pilot was terribly fatigued, stressed and confused.

 Situational Awareness.

  1. The situational awareness displayed by the pilots appears to be poor. They were high and fast on approach due to which they landed after 4900 ft. from the beginning of the runway. Why they landed after 4900 ft. has not been deliberated by the Investigation Team.
  2. Co Pilot appeared to be better situationally aware then the Captain while taxiing. If the Co Pilot could not see the center line markings due to rain, then Capt. also must have not been able to see the center line. However, the Captain failed to make any comments whether he can see the center line or not, in response to the Co Pilot who has been saying repeatedly that she can’t see the center line.
  3. When the Co Pilot as well as the Captain were not able to see the Center line marking, why they did not request ATC to increase the intensity of lights to high and also to switch on all the Taxi lights?
  4. Pilots had not realized that the Taxi Lights were on low intensity and only alternate lights were on and the fact that increase in the intensity of lights would have helped them to see better.
  5. The Captain turned 90 meters short of the Foxtrot Taxi Track without seeing/being sure, consulting or taking any help from the Co Pilot (who of course stated that when the pilot turned, she was cleaning her spectacle and adjusting wind screen wipers). Turning without seeing and not being sure, is strange and irrational act on the part of the Pilot.
  6. The action of the pilot to open throttle three times in attempts to come out of the drain in spite of the advice of the Co Pilot not to open throttle, is intriguing to say the least, since the action of the pilot to open throttle to move his aircraft forward when the aircraft was stuck in the drain, and the engines were resting on ground, could have resulted in catastrophic consequences.
  7. It appears that the Pilot was under the impression that he has encountered something minor which is affecting the forward movement of Aircraft and it can be overcome by opening throttle, least realizing that his aircraft was in a drain 3 meters wide and 1.7 meters deep. Surely, the pilots must have heard the thud and felt something very unusual when the aircraft nose wheel got into the drain, collapsed and the aircraft came to rest on its engines and belly with wheels dangling in the drain. The Pilot appears to have not paid any attention to the unusual occurrence. It is indicative of very high levels of fatigue/stress of the Captain who was unable to understand and cope with the situation.
  8. The pilots seemed to have no knowledge about the existence of the drain parallel to the Taxi track. There were no caution lights to indicate the presence of the drain.
  9. The ATC had no clue about the position of the aircraft after it landed and was confused about the communication between the Pilots and ATC.
  10. The ATC controller failed to activate the Airport Emergency Services in time even after knowing that the aircraft has got into ditch.
  11. The delay of almost 25 mts by the Fire tenders to reach the aircraft after the accident had taken place, can be attributed to the lack of correct information from the Pilots to ATC,lack of situational Awareness by the ATC controller and consequent delay in activating the emergency and fire services.
  12. The ATC Controller should have known that the taxi center line markings may not be visible to the pilots particularly in rain. (It must have been in the knowledge of the controllers that the taxi center line markings may not be visible since they have been receiving inputs from number of aircrafts during past months about the inability to see the center line marking. The ATC should have cautioned the pilots and switched on all the Taxi Lights on high intensity.
  13. ATC Controller should have known that the aircraft is landing in rain, in the night and during WOCL, after a long flight. Hence, he should have been more alert, vigilant and situationally aware. The ATC controller at that time was busy handling four aircraft and obviously was overloaded with work. The WSO should have been more involved in supervision and monitoring of the aircraft movement during this critical period of the operations.
  14. The Controller increased the intensity of Taxi lights after the accident which served no purpose towards prevention of the accident. If he had been situationally aware, he would have switched on all the Taxi Lights and increased the intensity of lights before the aircraft landed.

Aircraft Operator.

  1. The Operator’s Supervisors seem to have paid no attention to the issue of large Power Distance between the Captain and Co Pilot and the fact that the pilots were operating flight together for the first time.
  2. There appears to be inadequate emphasis on the problems associated with large Power Distance between Crew Members during the conduct of CRM Training by the Operator.
  3. The lack of knowledge of the Pilots about the Sea of Blue Effect is evident in this accident.
  4. The Station Manager/ Duty Officer/Dispatcher at Cochin did not seem to be aware about the problem related to sighting of the center line marking in rain by the Pilots. Even if they were aware, they did nothing about it.

Airport Operator.

  1. Subsequent to painting of the Charlie Taxi Track Center line in the Month of Mar, number of Pilots had communicated to the ATC about their inability to see the Taxi Center line, possibly due to its fading. The Foxtrot Taxi Track Center line was painted in the month of Jul. During the months of Jul, Aug and partly September, Cochin experiences heavy rains which would obviously degrade the painting of the center line. Airport Operator did not appreciate this important factor and no efforts were made to inspect the Taxi center line marking to confirm if they are visible or not. The quality of paint and painting standards also appear to be suspect.
  2. The Monsoons in the area of Cochin are quite heavy and Airport Operator should have taken adverse effects of Monsoon on the condition of painting of the center line into consideration. The condition of the Center Line markings should have been observed by the Safety Department of the Airport.
  3. The reflective markers were not available to indicate the presence and boundary of the drain at Cochin. It reflects poorly on the knowledge, involvement, supervision and proactive hazard identification of the Safety Department of the Airport.
  4. It is not known whether proper Internal, DGCA or Third Party Audit were conducted of the Cochin Airport. If conducted then how come such glaring issues were not highlighted.
  5. It is assumed that effective system of Hazard identification, reporting and addressing hazards before they turn into accidents, incidents have not been given due attention by the concerned officials.
  6. There were no SOP’s for switching on all the taxi lights to full brightness in the night particularly during poor visibility and rain which was the condition, in this case.
  7. The concerned officials were not aware of the problems associated with Sea of Blue Effect and suitable measures to eliminate or minimise these effects. As such, no SOP was issued for ATC controller to caution Pilots about the likelihood of Sea of Blue Effect.

Lessons Learnt.

  1. Proper Crew Pairing keeping in mind the Power Distance, interpersonal relations, team work and synergy, is of paramount importance for the conduct of safe operations.
  2. The aspect of two pilots flying together for the first time during expected adverse conditions like bad weather, long flight in the night during WOCL period, should be kept in mind by the Supervisors and adequate briefing of these aspects should be ensured.
  3. Power Distance has led to large number of accident, incidents. This aspect should be emphasized particularly during CRM and SMS Training.
  4. Need for open atmosphere in the cockpit, effective communication, team work and synergy are essential for safety and efficiency of Operations.
  5. There is no place for arrogance, overconfidence and complacency among pilots regardless of their experience, age, seniority and status.
  6. Inputs from the Co Pilot should not be ignored by the Captain and the Co Pilot need be more assertive if there is no response from the Captain to the repeated inputs from the Co Pilot.
  7. It is essential for the Cockpit crew to be situationally aware at all times and they should not hesitate to inform ATC if they are facing any problem related to the safety of the flight or unable to see the markings, Centre line or any other issues. They should not feel that the Controller will think poorly of them if they ask for some help. ATC will always be willing to help and respond to the Pilots request promptly.
  8. Pilots should not hesitate to ask for Follow me Jeep, increase in the brightness of lights and switching on all lights and any other related assistance as and when required.
  9. Airport Safety Department should be Proactive in identification of Hazards, addressing and eliminate them before they lead to accident/incident. The lack of visibility of the center line marking, problem associated with Sea of Blue Effect and absence of the reflective markers to indicate the presence of drain, should have been identified and action could have been taken to address these issues if the supervisors had ensured the Proactive identification of Hazards.
  10. The WSO should be more involved in supervising and monitoring the Operations especially during adverse weather and WOCL period.
  11. The fatigue factor, work load and level of the alertness of the ATC controller in the early morning hours during adverse weather conditions, should be kept in mind by the WSO/supervisory staff and accordingly level of supervision should be enhanced.
  12. The Airport Manager of the operator should be more involved, interact with the ATC and Safety Department to become aware of the grey areas related to safety of the aircraft and bring the same to the notice of the pilots so that the pilots are better situationally aware.
  13. The Operator should be accommodative of the request of the pilots if they inform the management that due to lack of sleep, fatigue and likely risk of compromise on safety, when operating in the WOCL, under fatigue conditions, they should not be detailed for the flight.
  14. The Pilots should also not hesitate to inform the Management that they are unable to undertake the flight due to any reasons, which can compromise safety. The Pilots will be encouraged to approach the Management if Management is known to consider the Pilots request favorably without any prejudice.
  15. The knowledge about Sea of Blue Effect should be imparted to the Pilots and ATC Controllers during recurrent training. The airports which are known to have conditions conducive to Sea of Blue Effect must be identified and the details should be circulated to all the operators to brief their pilots about it.
  16. The conduct of the Internal and DGCA Audit should be taken seriously. Third Party Audits are known to be very effective in identifying the hazards and the Airport Operators should not shy away from Third Party Audit.
  17. The Senior Management of the Aircraft and Airport Operator should pay special attention to Safety and Safety Management System (SMS).
  18. There should be accountability of the Accountable Manager to DGCA to ensure sincere implementation of SMS, addressing all safety related issues and promotion of safety in his organization.
  19. The time taken by the Inquiry team to complete the inquiry should not exceed three months in such accidents.
  20. There should be a system by which the lessons learnt from Accidents, Incidents can be disseminated to all the Pilots and Aircraft, Helicopter and Airport Operators.
  21. The Follow Up action on the Recommendations of the Investigation Team should be implemented in a time bound manner and DGCA may consider sharing the completion of implementation of the recommendations with concerned stakeholders.
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