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Fuel Starvation, Stress, Fatigue and Nonstandard Phraseology (OGHFA SE)
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|Content source:||Flight Safety Foundation|
|Human Factors Aspects||Pilot-Controller Communication, Standard Calls, Fatigue, Stress|
|Flight Phase||Cruise, Descent|
|Operator's Guide to Human Factors in Aviation|
| Situational Example
|Fuel Starvation, Stress, Fatigue and Nonstandard Phraseology|
The Accident as a Situational example
You are the first officer on an international flight toward a congested area. It is your second sector. The flight is scheduled to arrive at night.
As the flight proceeds to the destination, it is placed in holding three times by air traffic control (ATC) due to bad weather and heavy traffic. Total holding time has exceeded 1 hour 15 minutes when the en route controller advises you to expect further clearance in 20 minutes.
- What is your strategy for landing?
You respond that you will need priority handling because you cannot hold longer than 5 more minutes, are running out of fuel and cannot reach your alternate airport.
After consulting with approach control as to whether it could accept the aircraft, the en route controller clears you to your destination and instructs you to contact approach control.
You are given routine radar service, including descents to lower altitudes and heading changes to sequence you with other airplanes. The controller also informs you of wind shear.
Fully aware of the fuel shortage, you begin to discuss the procedure for a go-around, with less than 1,000 lb (454 kg) of fuel in the tanks.
During the approach, a little more than 30 minutes later, the ground-proximity warning system (GPWS) starts triggering multiple warnings.
- How do you react to the warnings?
The captain orders a go-around.
You are subsequently cleared for a new arrival track, and the final approach controller asks if this new track is all right with you regarding fuel.
Approximately 5 minutes later, and only miles from the outer marker for the instrument landing system (ILS) approach, all four engines flame out due to fuel starvation. The aircraft hits a hillside in a residential area. There is no fire. Among the people aboard the aircraft, almost half are killed, and the others are seriously injured, except for a few who suffer only minor injuries.
2 Data, Discussion and Human Factors
Investigators determined that the probable cause of this accident was the failure of the pilots to manage the fuel load and their failure to communicate an emergency fuel situation to ATC before fuel exhaustion occurred.
Investigators found a series of inadequacies in the dispatching services of the airline and in the flight plan issued to the crew. Despite this, sufficient fuel was loaded at the departure airport to complete the flight safely, and it was the flight crew that did not properly manage the fuel in flight.
The dispatch function plays a critical role in operations planning and flight conduct, especially for situations involving deteriorating weather and ATC delays. In these situations, the dispatcher can help the pilots manage their fuel and provide assistance in their decision making about the most prudent actions to ensure safety of flight.
That evening, numerous other flight crews who were waiting for clearances had contacted their respective dispatch facilities. Investigators could not determine why this flight crew did not use these valuable in-flight services as its fuel situation became progressively critical.
During the flight, the crew was aware of the fuel situation but did not express their concerns promptly and clearly to ATC.
When the crew requested priority handling, they had already exhausted the reserve fuel they needed to reach the alternate airport. To help ensure sufficient fuel to complete a safe landing, standard phraseology should have been used to declare an emergency, rather than priority handling. The first officer’s use of the term “priority” may have resulted from his training, where the term appeared in the manufacturer’s procedures manuals and in the published airline procedures.
Regarding the context of the situation, none of the controllers involved in the handling of the aircraft considered the request for priority or the comments about running out of fuel to be significant or to actually constitute a request for emergency handling. The en route controllers believed that the crew meant that the flight could only hold 5 minutes more and would then have to divert to its alternate, and therefore they handled the aircraft routinely.
Investigation revealed that this created confusion within the cockpit as to whether they were being handled routinely or given priority as an emergency would have called for.
When asked what phraseology controllers would immediately respond to when a flight crew indicated a low-fuel emergency, controllers replied “mayday,” “pan, pan, pan” and “emergency,” but not “priority.” Investigators concluded that the communications from the controllers and the handling of the aircraft were correct, considering the information they had received from the flight crew. Nevertheless, the investigation report expressed concern that the controllers did not place any significance on the word “priority” because controllers are in fact required to provide priority handling. Controllers share the responsibility for safe flight, although their primary responsibility is for separation of aircraft.
ATC is also required to clarify any confusing transmissions that might affect the safe operation of aircraft under its control. In this case, several indications of non-routine matters should have prompted the controllers to ask about the nature of the problem that caused the request for priority. Had they asked, the confusion that apparently existed within the cockpit might have been alleviated.
After the missed approach, intra-cockpit conversations indicate a total breakdown in communication between the pilots in their attempts to relay the situation to ATC. The captain repeatedly told the first officer to advise ATC they had an emergency. It is obvious from recorded radio transmissions that the first officer failed to convey the message that the captain intended, and investigators determined that the captain’s limited command of English likely prevented him from effectively monitoring the first officer’s transmissions.
Much of the pilots’ failure to communicate effectively resulted from limitations in their use of English and in their knowledge of standard ATC terminology. But investigators also pointed out shortcomings in the intra-cockpit communications, spoken in their native language, and the application of crew resource management (CRM) skills, when the flight crew was addressing operational problems. Specifically, the captain did not make use of dispatch and other resources available to him, and he did not demonstrate the leadership, decision making and management skills needed. Further, the first officer and flight engineer did not provide the kind of active team support the captain needed. Leading all communication, the first officer appeared to have assumed a slightly more influential role than the captain. The inability of the crew to effectively communicate as a cohesive team, with a strong leader, most likely created a weak CRM environment.
If the captain had been able to complete the first ILS approach and land successfully, the accident would not have occurred.
While wind shear was a factor, it was not the sole cause of the poorly flown approach. Other factors, both psychological and physiological, help explain not only the crew's performance of the approach but also the lack of anticipation of the wind shear and the absence of any discussion of the need to land on the first approach due to the fuel situation.
The aircraft had been flown manually, using raw data, for the majority of the flight due to recurrent problems with the autopilot and flight director. The hours of manual flying combined with the increasingly critical nature of the crew's situation are consistent with increased fatigue and adverse stress reactions. This situation is most evident in the captain's decreasing ability to share multiple tasks. Indeed, from the time that the airplane was on ATC’s final vector to the localizer until the missed approach, there were nine distinct instances when the captain asked for instructions to be repeated or for confirmation of the airplane's configuration. Additionally, the captain asked the first officer to speak louder. These events are all signs of fatigue and adverse stress.
These stress conditions are evident not only in the pilots’ performance of the ILS approach but in their failure to recognize that they could not conduct a missed approach. Moreover, when they did conduct the missed approach, they did not take control of the situation and request the shortest flight path back to the airport.
3 Prevention Strategies and Lines of Defense
One of the main causes of the accident was the crew’s failure to communicate the urgency of the situation, due to the use of nonstandard phraseology by the first officer, poor knowledge of English by the Captain and poor intra-crew coordination and communication.
If a pilot has limited English proficiency, he or she has to rely heavily on the meaning of the words he does know. If those words have a vague meaning, or if a clear set of terms and words is not used by pilots and controllers, confusion can occur — as it did in this accident.
If one of the crewmembers has inadequate knowledge of English, he cannot accurately monitor the transmissions of other crewmembers. This emphasizes the importance of the use of standard phraseology, which guarantees a common understanding among speakers with different native languages.
The following recommendations are for flight crews:
- Use “what if” scenarios likely to affect the mission. For example, if weather is bad at the destination, add fuel and do not accept a close-in alternate that could be affected by the same weather.
- Communicate clearly and directly. Do not “mince” words. If fuel on board is critical, inform ATC. If you think controllers are not getting the message, tell them again until you are sure they understand.
- Use standard phraseology in case of critically low fuel — “Mayday, Mayday, Mayday.” Then, to explain the situation, use simple and short messages that highlight the operational implications of the prevailing conditions.
- Work as a team to develop a clear plan of action. Had this crew worked better together, they might have conveyed the message to ATC.
The following recommendations are for controllers:
- In case of incomplete or confusing transmissions, request clarification from the flight crew; do not decide on the most probable interpretation yourself.
- In case of an emergency, provide maximum assistance and select and pursue a course of action that appears to be the most appropriate under the circumstances.
4 Key Points
This accident was preventable had the flight crew and controllers communicated better about the critical nature of the situation. The following key human factors recommendations can be made:
- Communicate clearly and directly. Do not mince words.
- Use standard phraseology. This prevents misunderstandings and second-guessing.
- Speak up. Repeat your message until you are sure it is understood.
5 Associated OGHFA Material
- Pilot-Controller Communications
- Fatigue Manifestations
- Stress and Stress Management
- Crew Resource Management
- Decision Making