Flying Touareg
1st Jun 2007, 08:21
Sosoliso accident report faults pilots' judgement blames on weather
</I>ON Saturday, December 10, 2005, the Sosoliso aircraft registered 5N-BED with call sign OSL 1145 departed Abuja at 1225 hours UTC on a scheduled passenger flight enroute Port Harcourt with 110 persons on Board (103 passengers and 7 crew).
The flight continued normally until final approach to Port Harcourt. The aircraft was carrying out an ILS approach to Runway 21 and had reported established on the glide and localiser at 6 miles to touch down. The controller then cleared the aircraft to land but to exercise caution as the runway surface was slightly wet and the pilot acknowledged.
Soon after, the aircraft made impact with the grassy strip between Runway 21 and taxiway i.e. 70m to the left of the runway edge and 540m from the Runway 21 threshold. At about 60m from the first impact, the aircraft tail section impacted heavily with a concrete drainage culvert and the aircraft then disintegrated and caught fire along its path. The total wreckage tail covered a distance of 1120m (1/12km). The accident resulted in 108 fatalities and 2 survivors.
The available runway 21/03, which is 3000m long and 60m wide, is designed to accommodate jet planes for take offs and landings. The runway is equipped with edge lights, Precision Approach Path Indicator (PAPI) and approach lights, which were serviceable but not available for use at the time of the accident. However the runway is not equipped with centerline lights. In practice at this airport, the airfield lightings, which are under the control of FAAN, are switched on at night (1800 hrs-0600 hrs UTC) and off in the day (0600 hrs - 1800 hrs UTC) except on request by pilots and, or when controllers observe deteriorating trend in weather conditions.
The reason for this practice is due to the unstable power supply from National Grids and lack of funds and resources to maintain the power from generating sets on a regular basis at the airport. Though there was a deteriorating trend in weather conditions when the aircraft was on final approach, the pilot neither requested for the airfield lightings nor did the Tower Controller request FAAN for the airfield ligthings to be switched on when they observed the deteriorating trends in weather conditions.
The navigational aids were all serviceable for use on that day and the aircraft was established on the ILS at 6 miles to touchdown. The ILS was calibrated on the 11th October 2005 barely two months before the crash. There had not been any report from pilots who have been using the facility of any malfunction nor its unreliability.
The exposed concrete drainage culvert located at about 70m to the left of runway 21 edge and 540m from the threshold portends serious danger to aircraft during landing and takeoff. The aircraft impacted heavily with the drainage culvert, which resulted into its disintegration and fire outbreak. The first physical evidence of fire was observed at about 200m from the culvert.
Flight Recorders
Flight Data Recorder (FDR)
The FDR read out indicates that the flight was normal until the last moment into the final approach to Port Harcourt airport. At 30 seconds before the crash, the airplane descended through 357ft (ASL) at the airspeed of 153 knots and a heading 207.3?. The airplane head at this point is a departure from its initial heading of 211?. At 23 seconds before the crash, the airplane levelled off at an altitude of about 240ft, which is below the Decision Altitude (DA) of 307ft (ASL). The altitude then remains relatively steady for the next 14 seconds. During this time, the airspeed decreased below 145 knots.
At 7 seconds before the crash, the airspeed began to increase reading 151.3 knots, the increase in speed would indicate an engine power in put by the crew to initiative a "Go Around". Meanwhile, the aircraft had sunk further below 204ft (ASL) and its heading deviated tot he left of the runway magnetic heading of 210?. The aircraft could not recover when the crew later decided to initiate a go-around. At the time of impact when the FDR recording stopped, the aircraft had a heading of 196.9? and airspeed of 160.2 knots and a descent rate well over 2000ft/min.
Cockpit Voice Recorder (CVR)
The conversation within the cockpit environment reveals that the flight was uneventful until the final approach to land. The CVR read out shows that the aircraft was configured for landing when one of the pilots called for gear down approach checklists.
At about 16 seconds tot he crash, the captain called for a go-around, gear up and flaps before the crash. A warning horn then came on followed by a too low gear aural sound from the cockpit area microphone. It appears that the crew had difficulty in sighting the runway and should have carried out a missed approach at the Decision Altitude (DA) of 307ft ASL instead of continuing descent below 204ft (ASL).
The gear was down and locked with the landing flap set prior to the go around. When the crew decided to go around, the flap lever was selected up while the gear was still in the extended position but probably not locked. The warning horn then sounded because the gears were no more in the landing position and the flaps had not yet retracted to less than approximately 18 degrees. The warning horn was immediately followed by the "too low gear" sound i.e. Ground Proximity Warning System (GPWS).
Weather Factor
On Approach to Port Harcourt
At 124 hours UTC, the aircraft was in contact with Port Harcourt Approach and the controller informed the aircraft to maintain FL 240 and to expect no delay on ILS approach to runway 21. Thereafter, the controller passed the weather report for 1230 hrs as: 260?/2kts, visibility 12km, nil weather, BKN 420m, Few CB (M-SE) at 690m, ONH 1008, temp 33? C; whereas this was the weather report for 1200 hrs.
The actual 1230 hrs weather report was 230?/08kts, visibility 12km, BKN 420m, Few CBN (several directions) and trend thunderstorm.
These two weather reports (1200 hrs and 1230 hrs) appear relatively the same with the exception of the Cumulonimbus (CB), which was in several directions and the trend thunderstorm. If the correct weather information were passed at the time, it would have placed the crew in the correct perspective on the weather situation to expect at the station. Invariably, the 1200 hrs report was the only detailed weather information available to the crew till the time of the crash.
At 1300 hrs, the pilot requested to know if it was raining over the station; to which the approach controller reported negative rain but scattered CB. Also at 1304 hrs, the approach controller informed the aircraft that from tower observation, precipitation was approaching the station; but no information about the wind direction and speed nor visibility were transmitted to the aircraft and neither did the pilot request for the information.
At about 1305 hrs, when the aircraft was in contact with the control tower, one would have expected the controller to give the aircraft the prevailing wind conditions to the pilot but instead, he only cleared the aircraft to land and to also exercise caution, as the runway surface was wet (neither did the pilot request for the wind).
Adverse Weather Phenomenon
The weather reports obtained from the Nigerian Meteorological Agency (NIMET) and the one compiled from the Satellite Imagery by the Boeing Aircraft Company (USA), both showed that there was a change in the wind speed and direction when the aircraft was approaching the station. The weather reported by the station and the pilot report (pirep) indicated fast deteriorating weather situation which was a low cloud condition with reducing visibility in thunderstorm and rain. This change in wind speed and direction contains ingredient of wind shear.
Wind Shear is defined as a change in wind speed and/or direction within a short time that takes place close to the ground. This change causes a shearing or tearing effect which is of great concern to pilots and the airline industry. A search of the National Transportation Safety Board (NTSB) database reveals that from 1st January 1980 to date, there were 238 accidents in which wind shear was a factor.
On the day of the accident, the aircraft which was coming in with a head wind in its approach soon encountered a tail wind on its final approach to land on runway 21. The pattern of the wind at the station is as follows:
260?/02knots @ 1200hours UTC (head wind)
230?/08 knots @ 1230hours UTC (head wind)
220?/09 knots @ 1300hours UTC (head wind)
360?/05 knots @ 1308hours UTC (head wind)
The problems aircraft have with adverse weather (which may be associated with wind shear activity) occur when they are flying slightly above stall speed such as case in point. When the airplane was flying with an increasing head wind, extra lift was generated by the increasing speed of the wind. And when the aircraft was on final approach, the wind changed to a tail wind with an attendant decrease in speed.
Aircraft Handling
At 6 miles to touch down, the crew reported established on the glide slope and localiser after which the tower controller cleared the aircraft to land. Shortly after, the aircraft encountered adverse weather conditions (headwind to tailwind). The crew was not aware of the prevailing adverse weather conditions since they were not equipped with actual wind situation.
AIPB is of the view that due to the reducing visibility in thunderstorm, rain and low cloud, the crew could not sight the runway particularly when the airfield lightings were not on. In the process, the crew descended well below the Decision Altitude (DA) of 307ft ASL before they decided to initiate a 'go-around."
Decision Altitude - 307ft (ASL)
Airfield Elevation - 87ft (ASL)
Therefore,
Decision Height - 220ft (ASL)
But the aircraft descent - 204ft (ASL)
Airfield Elevation - 87 ft(ASL)
Therefore,
Aircraft Height - 119ft (AGL)
Therefore, Deviation (Error) - Decision Height - Aircraft Height
220ft -117ft
103ft
This implies that the crew descended the aircraft below the Decision Height (DH) by 103ft and so was not fully prepared to execute a missed approach/go-around at the Decision Altitude.
The captain was on the radio until he commended 'go-around', gear up and flaps in quick succession. The warning horn then sounded because gears were no more in the landing position. The warning horn was immediately followed by the "too low gear" sound i.e. Ground Proximity Warning System (GPWS).
From the CVR analysis, there is an indication that the commander handed over the controls to the first officer about 25 miles to the station while the commander was on the radio until he called for 'go-around.' The hand over of the controls tot he First officer is allowed in aviation practice to enable the officer acquire more experience but nothing precludes the commander from taking over the controls if and when the need arises.
It would appear that the crew did not apply the correct procedure for a "go-around' from an ILS approach, even though records show that the crew received training for an ILS missed approach/go-around.
The normal procedure for a missed approach is
Set takeoff thrust.
Set flaps to 15?/slats extend;
Accelerate to V+10kts while rotating smoothly to between 13? and 17? pitch attitude and;
Retract landing gear after a positive rate of climb is established.
Even if the crew were carrying out a recovery from adverse weather associated with wind shear, the procedure adopted by the crew was improper.
Findings
The aircraft had a valid Certificate of Airworthiness and there were no known defects that could have contributed to the accident.
The crew had valid licence and qualified to fly the aircraft on the day of the accident except that the first officer had limited experience.
The simulate training attended by the crew was conducted by the airlines training captain abroad. However, both the training institutions and the training examiners were approved by the NCAA.
the aircraft, which departed Abuja enroute Port Harcourt, got in contact with the Approach controller at 1241 hrs UTC maintaining FL240.
Approach controller then gave the aircraft an in-bound clearance of no delay expected on ILS approach runway 21.
Thereafter, the Approach controller passed on 1200 hrs UTC meteorological report as wind of 2600 / 02kts, visibility 12km, nil weather. BKN 420m, few CB (N-SE) at 690m, QNH 1008 and temperature 330 C.
Basic meteorological equipment for measuring visibility and cloud conditions are lacking at the airport. However, the data generated by NIMET officials is in agreement with the data obtained from the Satellite Imagery from the USA.
The aircraft continued its descent until about 1300 hrs UTC when the crew asked approach whether it was raining over the station but the approach controller reported negative rain but scattered CB.
at 1304 hrs UTC, the crew reported established on the glide and localiser at 8 miles to touch down and the approach controller informed the aircraft of precipitation approaching the station from the direction of runway 21 before passing it to the control Tower for landing instructions.
At 1305 hours UTC, the aircraft contracted Tower and reported established on the ILS at 6 miles to touch down. The controller then cleared the airplane to land on Runway 21 while exercising caution as the runway surface was slightly wet. No wind information was given to the pilot and neither did he request for it.
the aircraft on final approach encountered adverse weather with change in wind speed and direction: 2200 / 09kts (head wing) in nil weather to 3600 / 05kts (tailwind) while the visibility was reducing in thunderstorm and rain.
The recording of the cockpit Voice Recorder was poor as there were problems of echo effect, unintelligible data and faulty erase function. This was however taken care off by filtering at the read out facility.
there was no standard instrument call-out by the crew as evidence in the CVR
the crew continued the descent and went well below the decision altitude without having visual contact with the runway.
the crew initiated a go around below the altitude of 240ft, which is 103ft below the decision altitude; the attempt of which was not successful. They were not fully prepared to execute a missed approach.
at about 1308 hours UTC, the aircraft tail section made contact with the grass strip between runway 21 and taxiway, 70m to the left of the runway edge and 540 from the runway threshold.
at about 60m from the first impact, the aircraft rear fuselage impacted heavily with an exposed concrete drainage culvert where No. 2 engine and the rear staircase of the aircraft were detached and lodged.
the exposed concrete drainage structure is badly located and poses a real danger to aircraft landing on runway 21.
the aircraft disintegrated and caught fire along its path spanning over 790m. The cockpit section with the forward fuselage was found at a further 330m from the rest of the wreckage trail on the taxiway giving a total wreckage distance of 1120m.
The response time of the fire services is reasonable (about one minute) except that they were hampered by wide spread fire covering 1.12km, very strong winds and inadequate resources.
The rescue team recovered 103 bodies and 7 survivors. Five(5) of the survivors later died in the hospital while two (2) are still receiving treatment.
Federal Airports Authority of Nigeria (FAAN), among other things, maintains and controls the airfield lightings (runway edge lights, approach lights and PAPI etc). These airfield lightings though were operational/serviceable were not on. In practice at the airport, the airfield lightings are switched on in the night (1800 hrs - 0600 hrs UTC) and off in the day (0600 hrs UTC - 1800 hrs UTC) except on request by pilots and, or when controllers observe deteriorating trend in weather conditions. This is as a result of lack of funds and resources to maintain the power supply on a regular basis. But no NOTAM was issued to that effect.
Probable Cause
The probable cause of the accident was the crew's decision to continue the approach beyond the Decision Altitude without having the runway and/or airport in sight
The contributory factors were:
The crew's delayed decision to carry out a missed approach and the application of improper procedure while executing the go-around.
The aircraft encountered adverse weather conditions with the ingredients of wind shear activity on approach.
The reducing visibility in thunderstorm and rain as at the time the aircraft came in to land was also a contributory factor tot he accident. And the fact the airfield lightings were not on may also have impaired the pilot from sighting the runway.
Another contributory factor was the fact that the aircraft had an impact with the exposed drainage concrete culvert which led t o its disintegration and subsequent fire outbreak. Recommendations
Where the training captains of Nigerian operators' conduct simulator training for their pilots at overseas institutions, the final check should be carried out and certified by instructors designated or appointed by the host country's Civil Aviation Authority for transparency.
Pilots flying into Port Harcourt and other coastal are as in the country should be mindful of weather hazards such as wind shear activity. Recognition and recovery from adverse weather/wind shear should be mandatory part of pilot's initial and recurrent simulator trainings.
NIMET should provide appropriate equipment to generate data on visibility and cloud conditions near the runway threshold and also ensure that adequately equipped briefing office is provided at the airport (and in all airports) for en route weather information among others.
There should be provision of on board wind shear detection/monitoring equipment and also at the airfield. There is also that need to carry out further studies into wind shear phenomenon at the airports
There is the need for the provision of Uninterrupted Power Supply (UPS) to the airfield lightings to ensure that all critical aids are on throughout the operational period of the airport. If this can not be achieved, the operational hours should be reduced/modified
The airfield lightings presently under FAAN Electrical Department should be transferred to NAMA so as to be regulated at the Control Tower in case of pilot's request for lighting intensity adjustment. Hence, the airfield lighting control at the tower should be reactivated. This is because the situation where controllers have to contact the FAAN Electrical Department to switch on or control the intensity of the airfield lightings is unacceptable and is not in consonance with the recommended practice.
The Airport Emergency Plan should be well structured and periodically tested with all the various agencies (FAAN, NAMA, City Hospitals and Red Cross etc) participating. Adequate fire cover should be provided at the airport (Category 8) otherwise, it should be appropriately graded.
Airline operators should be require to equip their aircraft with DFDR that is capable or reading several parameters (minimum of 32) and solid state CVR for enhanced recording.
The Nigerian Civil Aviation Authority, NCAA should monitor and strictly enforce standards on airfield lightings, fire cover and aviation personnel training.
http://www.guardiannewsngr.com/travels/article07
</I>ON Saturday, December 10, 2005, the Sosoliso aircraft registered 5N-BED with call sign OSL 1145 departed Abuja at 1225 hours UTC on a scheduled passenger flight enroute Port Harcourt with 110 persons on Board (103 passengers and 7 crew).
The flight continued normally until final approach to Port Harcourt. The aircraft was carrying out an ILS approach to Runway 21 and had reported established on the glide and localiser at 6 miles to touch down. The controller then cleared the aircraft to land but to exercise caution as the runway surface was slightly wet and the pilot acknowledged.
Soon after, the aircraft made impact with the grassy strip between Runway 21 and taxiway i.e. 70m to the left of the runway edge and 540m from the Runway 21 threshold. At about 60m from the first impact, the aircraft tail section impacted heavily with a concrete drainage culvert and the aircraft then disintegrated and caught fire along its path. The total wreckage tail covered a distance of 1120m (1/12km). The accident resulted in 108 fatalities and 2 survivors.
The available runway 21/03, which is 3000m long and 60m wide, is designed to accommodate jet planes for take offs and landings. The runway is equipped with edge lights, Precision Approach Path Indicator (PAPI) and approach lights, which were serviceable but not available for use at the time of the accident. However the runway is not equipped with centerline lights. In practice at this airport, the airfield lightings, which are under the control of FAAN, are switched on at night (1800 hrs-0600 hrs UTC) and off in the day (0600 hrs - 1800 hrs UTC) except on request by pilots and, or when controllers observe deteriorating trend in weather conditions.
The reason for this practice is due to the unstable power supply from National Grids and lack of funds and resources to maintain the power from generating sets on a regular basis at the airport. Though there was a deteriorating trend in weather conditions when the aircraft was on final approach, the pilot neither requested for the airfield lightings nor did the Tower Controller request FAAN for the airfield ligthings to be switched on when they observed the deteriorating trends in weather conditions.
The navigational aids were all serviceable for use on that day and the aircraft was established on the ILS at 6 miles to touchdown. The ILS was calibrated on the 11th October 2005 barely two months before the crash. There had not been any report from pilots who have been using the facility of any malfunction nor its unreliability.
The exposed concrete drainage culvert located at about 70m to the left of runway 21 edge and 540m from the threshold portends serious danger to aircraft during landing and takeoff. The aircraft impacted heavily with the drainage culvert, which resulted into its disintegration and fire outbreak. The first physical evidence of fire was observed at about 200m from the culvert.
Flight Recorders
Flight Data Recorder (FDR)
The FDR read out indicates that the flight was normal until the last moment into the final approach to Port Harcourt airport. At 30 seconds before the crash, the airplane descended through 357ft (ASL) at the airspeed of 153 knots and a heading 207.3?. The airplane head at this point is a departure from its initial heading of 211?. At 23 seconds before the crash, the airplane levelled off at an altitude of about 240ft, which is below the Decision Altitude (DA) of 307ft (ASL). The altitude then remains relatively steady for the next 14 seconds. During this time, the airspeed decreased below 145 knots.
At 7 seconds before the crash, the airspeed began to increase reading 151.3 knots, the increase in speed would indicate an engine power in put by the crew to initiative a "Go Around". Meanwhile, the aircraft had sunk further below 204ft (ASL) and its heading deviated tot he left of the runway magnetic heading of 210?. The aircraft could not recover when the crew later decided to initiate a go-around. At the time of impact when the FDR recording stopped, the aircraft had a heading of 196.9? and airspeed of 160.2 knots and a descent rate well over 2000ft/min.
Cockpit Voice Recorder (CVR)
The conversation within the cockpit environment reveals that the flight was uneventful until the final approach to land. The CVR read out shows that the aircraft was configured for landing when one of the pilots called for gear down approach checklists.
At about 16 seconds tot he crash, the captain called for a go-around, gear up and flaps before the crash. A warning horn then came on followed by a too low gear aural sound from the cockpit area microphone. It appears that the crew had difficulty in sighting the runway and should have carried out a missed approach at the Decision Altitude (DA) of 307ft ASL instead of continuing descent below 204ft (ASL).
The gear was down and locked with the landing flap set prior to the go around. When the crew decided to go around, the flap lever was selected up while the gear was still in the extended position but probably not locked. The warning horn then sounded because the gears were no more in the landing position and the flaps had not yet retracted to less than approximately 18 degrees. The warning horn was immediately followed by the "too low gear" sound i.e. Ground Proximity Warning System (GPWS).
Weather Factor
On Approach to Port Harcourt
At 124 hours UTC, the aircraft was in contact with Port Harcourt Approach and the controller informed the aircraft to maintain FL 240 and to expect no delay on ILS approach to runway 21. Thereafter, the controller passed the weather report for 1230 hrs as: 260?/2kts, visibility 12km, nil weather, BKN 420m, Few CB (M-SE) at 690m, ONH 1008, temp 33? C; whereas this was the weather report for 1200 hrs.
The actual 1230 hrs weather report was 230?/08kts, visibility 12km, BKN 420m, Few CBN (several directions) and trend thunderstorm.
These two weather reports (1200 hrs and 1230 hrs) appear relatively the same with the exception of the Cumulonimbus (CB), which was in several directions and the trend thunderstorm. If the correct weather information were passed at the time, it would have placed the crew in the correct perspective on the weather situation to expect at the station. Invariably, the 1200 hrs report was the only detailed weather information available to the crew till the time of the crash.
At 1300 hrs, the pilot requested to know if it was raining over the station; to which the approach controller reported negative rain but scattered CB. Also at 1304 hrs, the approach controller informed the aircraft that from tower observation, precipitation was approaching the station; but no information about the wind direction and speed nor visibility were transmitted to the aircraft and neither did the pilot request for the information.
At about 1305 hrs, when the aircraft was in contact with the control tower, one would have expected the controller to give the aircraft the prevailing wind conditions to the pilot but instead, he only cleared the aircraft to land and to also exercise caution, as the runway surface was wet (neither did the pilot request for the wind).
Adverse Weather Phenomenon
The weather reports obtained from the Nigerian Meteorological Agency (NIMET) and the one compiled from the Satellite Imagery by the Boeing Aircraft Company (USA), both showed that there was a change in the wind speed and direction when the aircraft was approaching the station. The weather reported by the station and the pilot report (pirep) indicated fast deteriorating weather situation which was a low cloud condition with reducing visibility in thunderstorm and rain. This change in wind speed and direction contains ingredient of wind shear.
Wind Shear is defined as a change in wind speed and/or direction within a short time that takes place close to the ground. This change causes a shearing or tearing effect which is of great concern to pilots and the airline industry. A search of the National Transportation Safety Board (NTSB) database reveals that from 1st January 1980 to date, there were 238 accidents in which wind shear was a factor.
On the day of the accident, the aircraft which was coming in with a head wind in its approach soon encountered a tail wind on its final approach to land on runway 21. The pattern of the wind at the station is as follows:
260?/02knots @ 1200hours UTC (head wind)
230?/08 knots @ 1230hours UTC (head wind)
220?/09 knots @ 1300hours UTC (head wind)
360?/05 knots @ 1308hours UTC (head wind)
The problems aircraft have with adverse weather (which may be associated with wind shear activity) occur when they are flying slightly above stall speed such as case in point. When the airplane was flying with an increasing head wind, extra lift was generated by the increasing speed of the wind. And when the aircraft was on final approach, the wind changed to a tail wind with an attendant decrease in speed.
Aircraft Handling
At 6 miles to touch down, the crew reported established on the glide slope and localiser after which the tower controller cleared the aircraft to land. Shortly after, the aircraft encountered adverse weather conditions (headwind to tailwind). The crew was not aware of the prevailing adverse weather conditions since they were not equipped with actual wind situation.
AIPB is of the view that due to the reducing visibility in thunderstorm, rain and low cloud, the crew could not sight the runway particularly when the airfield lightings were not on. In the process, the crew descended well below the Decision Altitude (DA) of 307ft ASL before they decided to initiate a 'go-around."
Decision Altitude - 307ft (ASL)
Airfield Elevation - 87ft (ASL)
Therefore,
Decision Height - 220ft (ASL)
But the aircraft descent - 204ft (ASL)
Airfield Elevation - 87 ft(ASL)
Therefore,
Aircraft Height - 119ft (AGL)
Therefore, Deviation (Error) - Decision Height - Aircraft Height
220ft -117ft
103ft
This implies that the crew descended the aircraft below the Decision Height (DH) by 103ft and so was not fully prepared to execute a missed approach/go-around at the Decision Altitude.
The captain was on the radio until he commended 'go-around', gear up and flaps in quick succession. The warning horn then sounded because gears were no more in the landing position. The warning horn was immediately followed by the "too low gear" sound i.e. Ground Proximity Warning System (GPWS).
From the CVR analysis, there is an indication that the commander handed over the controls to the first officer about 25 miles to the station while the commander was on the radio until he called for 'go-around.' The hand over of the controls tot he First officer is allowed in aviation practice to enable the officer acquire more experience but nothing precludes the commander from taking over the controls if and when the need arises.
It would appear that the crew did not apply the correct procedure for a "go-around' from an ILS approach, even though records show that the crew received training for an ILS missed approach/go-around.
The normal procedure for a missed approach is
Set takeoff thrust.
Set flaps to 15?/slats extend;
Accelerate to V+10kts while rotating smoothly to between 13? and 17? pitch attitude and;
Retract landing gear after a positive rate of climb is established.
Even if the crew were carrying out a recovery from adverse weather associated with wind shear, the procedure adopted by the crew was improper.
Findings
The aircraft had a valid Certificate of Airworthiness and there were no known defects that could have contributed to the accident.
The crew had valid licence and qualified to fly the aircraft on the day of the accident except that the first officer had limited experience.
The simulate training attended by the crew was conducted by the airlines training captain abroad. However, both the training institutions and the training examiners were approved by the NCAA.
the aircraft, which departed Abuja enroute Port Harcourt, got in contact with the Approach controller at 1241 hrs UTC maintaining FL240.
Approach controller then gave the aircraft an in-bound clearance of no delay expected on ILS approach runway 21.
Thereafter, the Approach controller passed on 1200 hrs UTC meteorological report as wind of 2600 / 02kts, visibility 12km, nil weather. BKN 420m, few CB (N-SE) at 690m, QNH 1008 and temperature 330 C.
Basic meteorological equipment for measuring visibility and cloud conditions are lacking at the airport. However, the data generated by NIMET officials is in agreement with the data obtained from the Satellite Imagery from the USA.
The aircraft continued its descent until about 1300 hrs UTC when the crew asked approach whether it was raining over the station but the approach controller reported negative rain but scattered CB.
at 1304 hrs UTC, the crew reported established on the glide and localiser at 8 miles to touch down and the approach controller informed the aircraft of precipitation approaching the station from the direction of runway 21 before passing it to the control Tower for landing instructions.
At 1305 hours UTC, the aircraft contracted Tower and reported established on the ILS at 6 miles to touch down. The controller then cleared the airplane to land on Runway 21 while exercising caution as the runway surface was slightly wet. No wind information was given to the pilot and neither did he request for it.
the aircraft on final approach encountered adverse weather with change in wind speed and direction: 2200 / 09kts (head wing) in nil weather to 3600 / 05kts (tailwind) while the visibility was reducing in thunderstorm and rain.
The recording of the cockpit Voice Recorder was poor as there were problems of echo effect, unintelligible data and faulty erase function. This was however taken care off by filtering at the read out facility.
there was no standard instrument call-out by the crew as evidence in the CVR
the crew continued the descent and went well below the decision altitude without having visual contact with the runway.
the crew initiated a go around below the altitude of 240ft, which is 103ft below the decision altitude; the attempt of which was not successful. They were not fully prepared to execute a missed approach.
at about 1308 hours UTC, the aircraft tail section made contact with the grass strip between runway 21 and taxiway, 70m to the left of the runway edge and 540 from the runway threshold.
at about 60m from the first impact, the aircraft rear fuselage impacted heavily with an exposed concrete drainage culvert where No. 2 engine and the rear staircase of the aircraft were detached and lodged.
the exposed concrete drainage structure is badly located and poses a real danger to aircraft landing on runway 21.
the aircraft disintegrated and caught fire along its path spanning over 790m. The cockpit section with the forward fuselage was found at a further 330m from the rest of the wreckage trail on the taxiway giving a total wreckage distance of 1120m.
The response time of the fire services is reasonable (about one minute) except that they were hampered by wide spread fire covering 1.12km, very strong winds and inadequate resources.
The rescue team recovered 103 bodies and 7 survivors. Five(5) of the survivors later died in the hospital while two (2) are still receiving treatment.
Federal Airports Authority of Nigeria (FAAN), among other things, maintains and controls the airfield lightings (runway edge lights, approach lights and PAPI etc). These airfield lightings though were operational/serviceable were not on. In practice at the airport, the airfield lightings are switched on in the night (1800 hrs - 0600 hrs UTC) and off in the day (0600 hrs UTC - 1800 hrs UTC) except on request by pilots and, or when controllers observe deteriorating trend in weather conditions. This is as a result of lack of funds and resources to maintain the power supply on a regular basis. But no NOTAM was issued to that effect.
Probable Cause
The probable cause of the accident was the crew's decision to continue the approach beyond the Decision Altitude without having the runway and/or airport in sight
The contributory factors were:
The crew's delayed decision to carry out a missed approach and the application of improper procedure while executing the go-around.
The aircraft encountered adverse weather conditions with the ingredients of wind shear activity on approach.
The reducing visibility in thunderstorm and rain as at the time the aircraft came in to land was also a contributory factor tot he accident. And the fact the airfield lightings were not on may also have impaired the pilot from sighting the runway.
Another contributory factor was the fact that the aircraft had an impact with the exposed drainage concrete culvert which led t o its disintegration and subsequent fire outbreak. Recommendations
Where the training captains of Nigerian operators' conduct simulator training for their pilots at overseas institutions, the final check should be carried out and certified by instructors designated or appointed by the host country's Civil Aviation Authority for transparency.
Pilots flying into Port Harcourt and other coastal are as in the country should be mindful of weather hazards such as wind shear activity. Recognition and recovery from adverse weather/wind shear should be mandatory part of pilot's initial and recurrent simulator trainings.
NIMET should provide appropriate equipment to generate data on visibility and cloud conditions near the runway threshold and also ensure that adequately equipped briefing office is provided at the airport (and in all airports) for en route weather information among others.
There should be provision of on board wind shear detection/monitoring equipment and also at the airfield. There is also that need to carry out further studies into wind shear phenomenon at the airports
There is the need for the provision of Uninterrupted Power Supply (UPS) to the airfield lightings to ensure that all critical aids are on throughout the operational period of the airport. If this can not be achieved, the operational hours should be reduced/modified
The airfield lightings presently under FAAN Electrical Department should be transferred to NAMA so as to be regulated at the Control Tower in case of pilot's request for lighting intensity adjustment. Hence, the airfield lighting control at the tower should be reactivated. This is because the situation where controllers have to contact the FAAN Electrical Department to switch on or control the intensity of the airfield lightings is unacceptable and is not in consonance with the recommended practice.
The Airport Emergency Plan should be well structured and periodically tested with all the various agencies (FAAN, NAMA, City Hospitals and Red Cross etc) participating. Adequate fire cover should be provided at the airport (Category 8) otherwise, it should be appropriately graded.
Airline operators should be require to equip their aircraft with DFDR that is capable or reading several parameters (minimum of 32) and solid state CVR for enhanced recording.
The Nigerian Civil Aviation Authority, NCAA should monitor and strictly enforce standards on airfield lightings, fire cover and aviation personnel training.
http://www.guardiannewsngr.com/travels/article07