B.1.2. System induced errors
B.1.2.1. Errors from complicated procedures
Errors from complicated procedures occur when a rule or procedure was not followed, and this either led to an incident or increased the risk of an incident happening. This goes against the basic safety agreement: All must follow the best known procedures and practices to achieve our safety outcomes.
This behaviour category happens when a rule has not been followed because either the rule or procedure was not known or not clear enough / not understandable or contradictory with another rule. This can be due to:
- The use of complicated language.
- Many cross-references or internal inconsistencies and conflicting messages in the documents.
- Not taking the level of the user of the procedures into account.
Sometimes people may act as if there is no procedure, due to:
- The procedures not being available.
- Lack of familiarity with the procedure.
International Example: The crew crossed the runway at number W11, in stead of continuing to taxi all around the runway at the south end, using taxiway Zulu, as they had been cleared to do by the traffic controller.
This certainly was not the intention of the crew. But what they found perhaps confusing, was that the tower controller cleared them “to cross 36C at Zulu”. Although the wording “Zulu” could not possibly be misunderstood about where they were supposed to be (Z->Z2->Z1->Z), it was the word “cross” that confused them. To them, this meant they had to physically be on the runway to “cross” it. But in correct ICAO language, the word “cross” is also used when the aircraft needs to taxi around the south end of this runway and needs to cross the holding line at Z2.
Many solutions have been tried to solve this. In the end, the aiport physically blocked both entries W12 and W11.
VNA Example 1: On flight SGN-HPH, after landing on CHC07, flight crew received instruction to “continue taxi and backtrack in your left side”. Flight crew was confused but still backtracked on CHC07 after confirming with ATC one more time. The correct instruction would have been “Vacate left N1 – turn round – RWY25…” following AIP’s instructions. As such, the aircraft turned around on CHC07 instead of on N1, near the end of CHC07.
As turnaround is not prohibited on CHC and the regulations to “Strictly follow ATC’s instructions”, flight crew had to do as instructed by ATC.
VNA Example 2: On 03/10/2011, aircraft A321-VN354 VN1505 HAN-DAD was moved beyond the allowed position 6 by 7.35m. VAEC staff deployed choke at the front wheel of the aircraft, but the main wheels were unsecured leading to the flight crew to remove brakes, causing the aircraft to drift forward by 2.9m and damage the stair vehicle. Engine 1 also lightly collided with an air blower vehicle.
Causes:
– Improper instruction by ACV leading the aircraft to stop 7.35m beyond allowed position.
– VAECO staff incorrectly deployed chokes as GOM instructions. – Chokes deployed were in poor conditions (damaged, old).
B.1.2.2. Errors from incorrect training or role
This behaviour category indicates errors which arise from incorrect or insufficient training to staff, or the personnel was incorrectly posted in his position.
When this type of behaviour category occurs, assessment of fitness to work – a test for the employee’s competencies and suitability for the job should be done:
- If the employee still demonstrates sufficient fitness to work, additional competence development and coaching can be provided to prevent repeated errors from occuring.
- If the employee cannot demonstrate sufficient fitness to work, management can consider assigning alternative types of work, or dismissal of employee entirely.
International Example: An United Airlines employee made the mistake of placing a TSA approved dog carry-on cage in the overhead compartment area. This led to the dog’s death at the end of the journey from Texas to New York.
VNA Example: On 01/04/2011, FAA sent warnings to Vietnam Airlines on the issue of not declaring potentially dangerous cargo on commercial flights. This is the bulk of aircraft equipment shipped for repair and within it was spare fuel – which is potentially dangerous material as per IATA’s regulations. Cause: The unit responsible for disassembling and packaging of the equipment was not instructed on procedures on how to recognize, evaluate and categorise spare parts on whether they are potentially dangerous materials. This led to the staff not packaging and declaring the parts correctly following IATA’s regulations.
B.1.2.3. Communication errors
System induced communication errors occur when there is contradictory, incomplete or incorrect communication that may lead to temporary safety risks.
International Example: Passengers on Qantas flight QF94 experienced a sudden ‘free fall’ that lasted about 10 seconds. In a later statement, Qantas chief pilot explained that QF94 was about 37 kilometres behind another Qantas A380 when it experienced a wake turbulence. The lack of prior communication between the flight crew with passengers, as well as communication between pilots flying the same corridor caused a small panic during the flight.
VNA Example 1: Mishearing ATC’s instructions:
After the flight crew of VN773 SGN-SYD received the instruction “Boree Seven Papa (Boree 7P)”, the flight crew confirmed as “Boree Seven Alpha” but was not corrected by ATC. Afterwards, ATC proceeded to instruct approach towards CHC 16R but did not repeat the approach. After the flight, the Australian authorities provided acknowledgements of the confusion on the approach of the flight.
VNA Example 2: On 03/10/2013, during the extraction of spare fuel from aircraft A321, coded VN-A332 before flight VN540-WNZ-DAD, there was confusion between technical staff and fuel staff (language barrier), causing overflowing of fuel on the airfield, causing safety risk.
