Flybondi 737-800 LV-HQY (c/n 34406/1852) experienced a tailstrike while attempting takeoff from Iguazu (IGR) in the early hours of 16Jul18.
The final accident report was published by the Argentine JST (Junta de Seguridad en el Transporte) of the Ministry of Transport on 17Oct20.
* Tailstrike before Rotation
This incident was remarkable in that the tailstrike did not happen upon rotation or overrotation of the aircraft during takeoff but at the beginning of the takeoff roll down the runway ! The nose pitched up on its own causing the rear belly of the aircraft to strike the pavement.
* Most Passengers Seated in the Aircraft Rear
LV-HQY had a load of 65 passengers, nearly all of which were seated behind Row 15 of the aircraft plus 450kg (900 lbs.) of freight in one of the rear baggage bins too. Had the imbalance been any worse, the aircraft probably would have tipped onto its tail at the gate. Had it been a bit less, the plane would likely have continued its takeoff roll, coming to rest on its tail upon attempting rotation while still moving forward, perhaps exiting the runway at a very high speed, colliding with whatever lay beyond its end.
So how did the aircraft come to be so out of balance and why was this not discovered before leaving the gate ?
Factors that might have contributed to the accident:
* Cheapest Seats in the Rear
The initial reason for the 65 passengers being seated so far aft is that Flybondi sold seat assignments with the cheapest seats all being in the rear of the cabin.
Had the plane been nearly full this would not have caused balance issues but with no travelers occupying the more expensive seats towards the front of the cabin there was a disproportionate amount of weight in the rear.
* Dispatch Subcontracted
Flybondi subcontracted the dispatch role (technical flight planning, including the "weight & balance" of aircraft) at Iguazu (IGR) to Flyseg S.A.
The Flyseg dispatcher calculated the weight & balance based on the distribution of passengers in the cabin given to him by Flybondi.
The computer systems of the two companies were incompatible and there was no procedure in place for transferring the information from one system to the other so the dispatcher manually transferred the passenger seating data, introducing the potential for error.
* Passenger Distribution Entered Incorrectly in Load Sheet
The load sheet produced by the dispatcher for this particular flight had a passenger distribution in the cabin that differed from where passengers were actually seated, leading the dispatcher to incorrectly calculate that the aircraft was within balance limits, but it was not.
The dispatcher passed the load sheet bearing these mistakes to the captain commanding the flight.
* No Double-Checking
According to Flybondi's operations manual, the dispatcher should visually check the aircraft for passenger seating distribution when entering the aircraft to give the load sheet to the captain but he reportedly did not do so on this flight.
Flybondi's operations manual also did not require the dispatcher to give a copy of the load sheet to the cabin crew nor did it require that the cabin crew check the passenger distribution on the sheet to make sure it was correct.
* No Safety Managememt System
Flybondi did not have in place a safety management system (SMS).
The airline was supposed to put one together but it grew rapidly between its startup in January 2018 and the July date of the tailstrike and the SMS was apparently neglected. The carrier was supposed to implement a "post certification surveillance" with the participation of the Argentine ANAC aviation authority but this was reportedly never put into practice.
Other factors that might have played a role in the accident:
* Seating Reconfigured
LV-HQY's seating was reconfigured to 189 seats two months before the incident which would have altered the weight & balance calculations but Boeing was not advised of this change so the aircraft's Weight & Balance Manual (WBM) was not updated correctly.
* 737-200 Calculations
The WBM was further incorrect in that some of the data for calculating weight & balance were based on the 737-200 model, not the 737-800.
* Safe Ending this Time
In the end, LV-HQY started to accelerate down Iguazu's runway 31 with the aircraft beginning to experience pitch up moments caused by the engine thrust resulting in its tail striking the runway surface. The crew was able to reject the takeoff uneventfully and taxied back to the ramp. But it could have been much worse.
Please note that the editor of this blog is informed to a degree on aircraft operational matters but is not an expert so he might not have interpreted all of the information correctly.
The actual accident report (in Spanish) can be found at this link:
Sources:
