Analysis of Serious Landing Incident-B 737-800 Dhaka- 22 Jan 17 and Lessons Learnt
B 737-800 aircraft, while operating flight (Mumbai to Dhaka) was involved in a serious incident at Dhaka on 22.01.2017 while landing.
The aircraft was under the command of Captain holding ATPL with First officer holding CPL.
There were a total of 160 passengers and 08 crew members including a supernumerary First Officer undergoing observation flight on board the aircraft.
Pilot – in – Command: Age 39 years, License ATPL holder, Total flying experience 5584:39 hours, Experience on Type 1444:33 hours.
First Officer. AGE 47 years, License CPL holder, Total flying experience 3329:56 hours, Total flying experience on type 3042:32 hours.
The crew carried out normal ILS DME approach for runway 18.
After the approach was stabilized, PF initiated flare at the recommended Flare height but the thrust lever was not retarded to idle as required by the FCTM for landing, so it was a power on landing.
The PF was not cautioned by the captain who was supervising the landing. On initial touchdown with a pitch attitude of 4.57 Degrees, ‘g’ of 1.55 was experienced causing the aircraft to bounce for 02 feet in air.
Speed Brakes got deployed as the system sensed aircraft on ground.
At this moment, Captain took over controls and increased thrust commanding 64.88% N1 to recover from bounce, this could have been avoided for small skip (As per the FCTM).
The pitch was also lowered to 2.11 degrees and DFDR data shows speed brake to be still up. The aircraft touched down on wheels for the second time with a vertical Acceleration of 2.79 ‘g’ and pitch attitude of 6.5 Degrees, speed brakes still up.
A pitch up trend @ 3.42 degrees/ second continued with a maximum pitch angle of 9.67 degrees.
Probably the main landing gear oleo strut which got compressed during the first touchdown might not have gone back to a fully extended position as it takes time, whereby reducing the distance between the bottom of fuselage of the aircraft and the ground at the time of second touchdown.
The aircraft attitude due to the combination of all the above at the time of second touchdown resulted in the fuselage bottom rubbing the ground as observed after the incident.
Training Records of the crew
The Captain was found consistent on all stages of training with some deficiencies in Situational Awareness, handling of aircraft (on manual as well as automation assisted) and certain inconsistencies of Procedures, FCTM and CRM techniques.
The First officer was found with deficiencies in instrument scan during Manual ILS approaches and situational Awareness.
Scrutiny of the files in both the cases as above have not revealed any details of training profile for corrective training.
Probable Cause of Tail Strike
Bottom of fuselage rubbed with runway surface as the First officer (PF) initiated flare but the thrust lever was not retarded to idle resulting in Power-On landing causing the aircraft skip of around 2 feet.
The Captain (PM) who was supervising the landing had not cautioned the PF to retard thrust levers to idle. In view of the skip, the Captain took over controls (became PF) and initiated recovery procedure by increasing the thrust which should have been avoided for small skip. As the aircraft system sensed the aircraft on ground, the speed brakes got deployed.
The Captain (PF) raised the nose further to smoothen the second touchdown, which resulted in insufficient fuselage clearance thereby causing the rubbing of fuselage with runway surface.
The First officer (now PM) did not caution PF about the aircraft’s pitch attitude.
Comments by Aviation Safety Management Society of India (ASMSI)
Absolutely, avoidable serious incident which could have resulted into a serious or major accident, that too in a foreign country, with serious complications.
Although the First Officer had almost twice the number of hours on the type than the Captain, yet the Captain had overall flying experience 2000 more that the First Officer. The Co Pilot was almost 8 years older than the Captain. This type of crew combination may pose CRM problems at times.
During this flight, the First Officer was Pilot Flying (PF) and the Captain was Pilot Monitoring (PM). The First Officer was carrying out assisted approach under the Supervision of the Captain (PM).
The PM after observing that the PF had established himself on the ILS approach, seem to have become complacent and was not aware of the Situation in the Cockpit. As a result he failed to notice that the power was still on when the PF flared and touched down with Power, and consequently bouncing around 2 ft.
If the PM was alert he would have cautioned the PF to bring power to Idle at the time of flare and touch down.
When the aircraft bounced by about 2 Ft on touch down, the PM took over controls to avoid hard landing. However, since the PM was not fully aware of the situation or not aware about the degree of bounce, he, on impulse applied excessive power to smoothen the landing.
As per the training manual, for small bounce of up to around 2 ft. there is no need to apply power or give any control inputs. However, the PM in panic applied excessive power and allowed his attitude to go beyond safe touch down attitude which led to the tail and part of rear fuselage scrapping the ground.
The PM appeared to be unaware of the correct bounce recovery procedure and the PF failed to caution him about excessive nose up attitude. It appears that the PF was disturbed mentally since the aircraft bounced during landing and the PM had to take over controls. Thereafter, he remained a mute spectator and did not caution the PM about high nose up attitude before touchdown or did not appreciate high nose up attitude.
It is interesting to note that both the Pilots were found deficient during training and checks related to Situational Awareness and handling of the aircraft both manually and on auto pilot. The same was found to be endorsed in the training records of the Pilots. However, no corrective training was undertaken to address the deficiencies observed. This is a serious negligence on the part of the Senior Supervisors of the Operator and unfortunately this lapse also was responsible for causing this serious incident.
This serious incident was caused due to complacency, lack of knowledge about the procedures, poor Situational Awareness and improper CRM, as well.
It is a known fact that the safety margin is minimum during approach and landing phase. Hence it is essential that both the Pilots are alert, vigilant, not complacent and are fully Situationaly Aware.
Both the pilots should be ever ready to handle any contingency which may develop at any time, more so, during approach.
No one is invulnerable and incident/accident can happen to anyone at any time. This aspect should always be kept uppermost in the mind of Pilots.
Proper knowledge about the bounce recovery, missed approach and behavior of the aircraft under various operational and weather conditions, should not be ignored.
Approach briefing covering various aspects of the approach and clearly defining duties and responsibilities of each crew member are essential safety requirement.
The deficiencies observed during the pilots training and proficiency checks should be rectified by the supervisory staff of the Operator through corrective training and close monitoring.
Any lapse on the part of Supervisors to monitor the conduct of training and operations should be viewed seriously.DGCA needs to send a clear message to the Accountable Executive and Senior Supervisors that any lapse on safety on their part will invite appropriate action against them.