Gear-Up Landing (OGHFA SE)
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Revision as of 14:38, 24 September 2009 by Anonymous
|Content source:||Flight Safety Foundation|
|Operator's Guide to Human Factors in Aviation|
Human Factors Aspects: Misunderstanding, Crew Resource Management (CRM), Adherence to SOPs
Flight Phase: Cruise
1 The Accident as a Situational Example
The crew comprises a very experienced captain and instructor who is relatively new to the airline, you, the first officer, flying your last initial operating experience (IOE) flight, and the flight engineer, on his first flight after type qualification. One hour after takeoff, an oil leak forces you to shut down the no. 1 engine and to return to the departure airport. You are the pilot flying. The flight proceeds normally until the final approach. The landing gear warning sounds when the flaps are extended to 25 degrees. The captain comments about this, and the flight engineer remarks about extending the flaps simultaneously with the alarms ringing.
- Do you consider that the landing gear situation is now resolved?
Standard operating procedures (SOPs) require the captain to ask the flight engineer to check the five lights on his panel. The captain asks, casually, “How many lights do you have back there?” and the engineer replies, “Four greens.” After checking the backup system, the captain confirms this status in a monotonous voice. He believes the landing gear is extended correctly and proceeds with the final approach. You are concentrating on flying the approach and believe the same, without paying too much attention to the conversation.
However, the approach speed is 26 kt above target, the flaps are still extending and the landing checklist has been interrupted by the alarm.
- Do you continue with the approach?
The approach is not stabilized, but the captain decides to proceed due to the long runway available and because you have another rotation after this flight and you are approaching your maximum duty time.
A few seconds later, the main landing gear touches the runway, but the nose landing gear is not extended. The airplane skids on its nose for about 800 m (2,625 ft) and comes to a complete stop on the runway centerline, without any injuries to the passengers or crew.
2 Data, Discussion and Human Factors
The accident report showed that there was not one single cause, but that several contributing factors led to the outcome. Those factors are summarized below for the sake of completeness, and we will focus on human factors issues such as: nonstandard callouts by the captain; misunderstanding between the captain and flight engineer on the landing gear status due to the latter’s insufficient knowledge; and inadequate Crew Resource Management that led the crew to perform in an “egocentric” manner, rather than as a team and without cross-checking each other.
Organizational factors — including rushing the airplane into service, verification of crew training and knowledge — were among the latent failures that led to the accident.
2.1 Active failures
- The captain did not use correct terminology or standard calls when he asked the flight engineer to check the landing gear lights. Rather than asking how many lights the engineer had “back there,” the correct question should have included mention of the required five lights. This would have attracted the captain’s attention when the reply was that (only) four lights were green.
- The flight engineer did not notice the warning on his panel that indicated the nose landing gear was not extended.
- The first officer did not object to or draw the captain’s attention to the nonstandard callouts because he was concentrating on the non-stabilized approach.
- Neither the captain nor the first officer perceived the true meaning of the “four greens” reply from the flight engineer.
- The high level of noise on the flight deck, the failure to use the intercom while wearing headsets and the flight engineer’s low monotonous tone of voice contributed to the captain’s misunderstanding the true meaning of the reply.
- After the initial exchange between the captain and the flight engineer, no further cross-checking action by the crew clarified the ambiguity between the real status of the nose landing gear and the pilots’ mental representation that the gear was extended.
- The captain used CRM inadequately by referring to an SOP without informing the rest of the crew of his intentions.
- The pilots did not go around despite the non-stabilized approach, the continuous landing gear alarm, the interrupted landing checklist, the still-extending flaps and the excessive speed.
- It appears that the crew did not perform as a team due to inadequate airline training in CRM and SOPs.
2.2 Latent failures
- The airline rushed the airplane into service for economic reasons. The airplane’s operating manual and its distribution were inadequate.
- Company SOPs had not been introduced when the flight engineer was trained and were constantly updated during training, leading to some confusion among the trainees.
- The flight engineer’s knowledge and proficiency were not adequately checked. He had difficulty adapting to the airplane during training and failed his first flight test.
- CRM training in the airline’s curriculum was shorter than the current internationally recommended level and could therefore be considered substandard.
3 Prevention Strategies and Lines of Defense
Following the accident investigation, the airline initiated corrective measures based on an external safety audit. The emphasis was on creating a safety culture by establishing an independent flight safety department.
Awareness of CRM and its associated training were improved, as well as crew selection and skills checking. Flight manuals, checklists and emergency procedures were reviewed and updated. Furthermore, procedures for introduction of new airplanes into service were also improved.
4 Key Points
- Adherence to standard callouts helps improve safety.
- Adequate crew communication, as described in CRM, is critical for risk reduction.
- A safety culture must exist throughout the airline.
5 Associated OGHFA Material