YK-AHB 747SP Syrian ( c/n: 21175 )
11:th of December 2006. Damage: 1 meter hole in the left leading edge of the wing.
Summary
The aircraft, a Boeing 747SP, had landed at Stockholm/Arlanda Airport
after a scheduled flight from Damascus. When taxiing in to the gate the
pilots were guided regarding distance and lateral deviations from a display
board on the terminal building.
The display was programmed by an operator from a handling company. She had received information about the arriving aircraft type from the data system at the airport, where the type code 74L was stated.
She was not familiar with this specific code, but presumed it was a standard Boeing 747, which her colleagues also assumed.
At the operators panel in the airbridge housing she programmed B 747
after have deleted the first version alternative which was B 747SP. The
reason why 747 was first choice in the versions list, was that there had been
accidents earlier at the airport when wrong version had been entered at the
displays.
A standard B 747 is longer than a SP-version, implying that parking is considerably closer to the terminal building. The computer system laser scans the front profile of the parking aircraft to confirm that the correct type is programmed.
Some gates at Arlanda have versions of this system that can separate different versions of the same aircraft type ( B747 – B 747SP). This modification was not implemented at the actual gate.
When the aircraft was taxiing in towards the gate the display indicated the type version B 747, according to the computer log in the system. During the interview the Commander stated that he earlier had experienced that docking systems had displayed B 747, and yet had been correct for a B 747SP.
The operator supervised the intaxiing and when she realized that the aircraft came alarmingly close to the airbridge housing, she activated the emergency stop button. This was however already activated by the ground staff at the ramp. The top of the left wing struck the under side of the airbridge at the same time as the display indicated “STOP” and a large hole was torn up at the upper side of the wing.
Recommendations
The Swedish Civil Aviation Authority is recommended to:
• Via the airport work for that proficiency in different versions of aircraft types is introduced into the training curriculum for gate operators (RL 2007:23e R1).
• Ensure that a relevant safety and quality control system for airbridge operators and guidance systems for docking aircraft is present. (RL 2007:23e R2).
• Ensure that the gates concerned at Arlanda airport are equipped with updated docking systems that can distinguish between different versions of the same aircraft type (RL 2007:23e R3).
• Work for that all docking terminals at Arlanda airport are designed in a way that information regarding aircraft types and type versions not can be misinterpreted. (RL 2007:23e R4).
Note.
CAA: Swedish Civil Aviation Authority (Luftfartsstyrelsen)
LFV: Swedish state enterprise running airports and providing
Air Navigation Services (Luftfartsverket)
Factual Information
History Of The Flight
The accident
On 11 December at 05:56 Syrianair flight RB 447 landed at
Stockholm/Arlanda airport after a scheduled flight from Damascus.
Syrianair’s traffic at Arlanda is mainly carried out by Airbus 320 aircraft,
but due to a large number of passenger bookings, a Boeing 747 SP1
was used
for this flight.
The landing and the first part of taxiing in took place completely
normally, and the pilots were advised to park at gate 18. During the final
part of taxiing, towards the final parking position at the gate, the pilots were
guided by a high intensity LED display on the wall of the terminal building
forming part of the automated docking system and providing information
concerning azimuth position and the distance to run to the stop position at
the airbridge. As the aircraft taxied in towards the gate, the airbridge
operator was located at the operator’s panel on the inner side of the
airbridge housing and had her attention focused on the LED display.
As the aircraft approached the airbridge the operator became nervous,
thinking it was coming rather close, and crossed over to the outer side of
the airbridge in order to get a better view. When she realised that the
aircraft wing was too close, and a collision was unavoidable, she ran back to
the panel and pressed the emergency stop button. The apron staff on the
ground below the airbridge housing also realised that there was about to be
a collision and therefore activated the emergency stop on the panel that is
located at ground level.
At the same moment that “STOP” appeared on the LED display the
aircraft collided with the airbridge. The top of the aircraft left wing struck
the underside of the airbridge housing and continued a little further, to
become wedged in place. A large hole was made in the structure of the top
of the aircraft wing. The airbridge also suffered damage. When the engines
had been shut down the cabin services manager went into the cockpit and
said that the aircraft had run into the airbridge, and that there was a hole in
the top of the left wing. No-one was injured, and all the passengers could
leave the aircraft in a normal manner.
The Handling Agent
Before parking, the handling agent’s operator at the gate had received
information via the airport computer system that the aircraft that would park would be a 74L, which is the international IATA2 code for the B 747SP.
She was not familiar with the 74L nomenclature and so asked her supervisor and colleagues for advice. The supervisor did not know either, but the colleagues thought it was a “normal” Boeing 747 and that “DOOR2”, the rearmost of the two front doors, would be used.
When preparing the display program to guide the aircraft into its final parking position, she therefore first tried to enter “DOOR 2” into the program after selecting B 747 as the aircraft type. However the system was programmed so that B747SP is pre-selected when selecting B 747 due to an earlier accident that occurred at Arlanda (see 1.18.3). The B 747 SP only has “DOOR 1” and so “DOOR 2” could not be selected, because the system would not accept this combination.
1 B 747SP (Special Performance) is a shorter version of the B 747
2 IATA = International Air Transport Association
She therefore entered the code that was equivalent to B 747, upon which the LED display, according to the system’s internal log showed: “B 747” – “2 DOOR”. This message, where “B 747” and “2 DOOR” flash alternately on the LED display, is intended for normal versions of the aircraft, which, due to the longer distance from the nose to the wing, park about 6 metres further forward than the shorter SP version.
The gate operator told SHK that she had not received any training and/or information concerning different versions of the same type, nor had she been informed about the situations that can arise when entering the incorrect version of certain aircraft types into the panel.
Commander
When interviewed, the commander stated that he had only noticed the text “B 747” on the LED display while taxying towards gate 18. He did not think this was strange, since when docking at a number of other airports he had seen that the docking system showed B 747 although it was set for the 747SP. He followed the instructions on the display as usual, with small azimuth adjustments, and at the same instant the display showed “STOP” the crew felt a shock run through the aircraft.
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