If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user
ETOPS Diversion at Night (OGHFA SE)
|Content source:||Flight Safety Foundation|
|Human Factors Aspects||Crew Resource Management, Decision Making, Fatigue, Alertness|
|Operator's Guide to Human Factors in Aviation|
| Situational Example
|ETOPS Diversion at Night|
The Incident as a Situational Example
You are flying an eastbound transatlantic route at night. The flight is planned for a northerly route to benefit from upper-level winds toward Europe. Established in cruise at Flight Level (FL) 350, flying toward 69N/90W, the relief pilot has been sent back for the first rest period. The first officer is going to take the next rest break and you the last.
The first alternate is an airport at 90W, the second is at 20W, the next is in Europe, as a closer one in Iceland is forecast to be down to 400 ft broken, albeit with adequate visibility.
Approaching 90W, you notice that oil quantity is dropping on the no. 2 engine. At this point, both you and the first officer look in the logbook for oil checks and notice no oil has been added for some time, indicating a good engine up to the moment you took over the airplane.
What is your diagnosis of the engine oil situation?
You assume the oil loss is real and contact dispatch. The reply from dispatch is that it is likely an indication problem, so you consult the flight crew operating manual (FCOM) and the quick reference handbook (QRH). These documents advise pressing on in the absence of any pressure and temperature changes.
However, the fall in oil quantity does not cease, and the level would reach zero by 70W. Diversion would become a matter of necessity in case of significant oil pressure or temperature changes. You consider alternatives, such as flying back 150 minutes, diverting to another airport 120 minutes away with a 7,500-ft (2,286-m) runway but good facilities, or diverting to another airport that is possible to reach in a short time, although with poor weather.
What is your decision?
You decide to continue, and inform dispatch. Up to now, the cabin crew has not been informed of any problems. When the airplane crosses 60W at 73N, some 300 nm (556 km) south of Greenland, the first officer returns from his rest, unable to sleep. Oceanic air traffic control (ATC) clears you to cross 40W at 72N. You collect all weather data at alternate airports via Satcom while discussing diversion options.
You decide to divert at the first indication of any other problems, be it an oil temperature or pressure drop, or a pressure differential of 20 psi. With oil pressure and temperature having remained at the same level for the entire flight, you decide to climb to FL 370 at 40W.
Some 15 minutes after getting there, no. 2 engine oil pressure starts to drop.
What is your next move in view of the developing situation?
You decide to divert and transmit a “pan” call, requesting clearance to an airport 313 nm (580 km) southwest.
Iceland Control gives an immediate clearance via HF and arranges for a phone patch to dispatch so as to supplement the data link.
What task sharing are you implementing at this stage?
You advise the cabin crew. They prepare promptly for the landing and inform the passengers of the precautionary diversion. You initiate a drift down, throttling back the no. 2 engine, rather than shutting it down. The first officer and relief pilot review the approach the first officer has entered in the flight management system (FMS), while you remain pilot flying. The diversion is made easier by the use of radar vectoring during descent with clear and concise English from the controller.
Prior to 40W, the LOC/DME ADF approach is reviewed in detail. The crew notes 2,800-ft terrain close to the airport and that, although the engine-out route for takeoff calls for a left turn, the missed approach requires a right turn.
The approach chart shows several fixes with altitude constraints, with only three listed in the FMS at 15 nm, 8.7 nm and 2.6 nm with altitudes of 3,300 ft, 3,100 ft and 476 ft.
ATC offers an early localizer intercept at your discretion. The signal is well received to follow the north shore of a fjord with excellent daylight visibility of terrain with steep hills. The runway is 9,500 ft (2,896 m) long and has a pronounced upward slope for a quarter of its length, making it appear short, with a precision approach path indicator (PAPI) on the left.
The airport, which is well equipped to deal with such unplanned occurrences, cooperates fully. Inspection of the engine later shows a rupture between the main oil filter and the engine supply line, with 4 L (4 qt) of oil remaining after shutdown. Although the engine was not shut down during the incident flight — so as not to spoil extended operations (ETOPS) statistics — no damage resulted.
Data, Discussion and Human Factors
Well managed, this incident did not result in any harm or in any form of airplane damage.
Situational awareness was refreshed from early on in the flight. Approaching 90W, the captain noted that the oil quantity was dropping on no. 2 engine. Up to then, the captain and his first officer, who was new to the aircraft type, had been discussing diversions — where to find charts, what sort of approaches to select, terrain limits and approach minimums, runway lengths and airplane weights, diversion options and terrain features. This was to manage fatigue and alertness, to refresh memory with operational facts, as well as to keep attention high, adding perspective to problems and maintaining situational awareness.
However, the drop in oil quantity did not abate and reached zero by 70W. Diversion became a matter of progressive decision making in case of significant further oil pressure or temperature changes. Various diversion alternatives were considered.
With excellent crew resource management, the decision was taken collectively to divert at the first indication of any other problems, be it oil temperature or pressure drop or a differential with the other engine of 20 psi.
This happened after it was decided to climb to FL 370 at 40W. Some 15 minutes after reaching there, no. 2 engine oil pressure started to drop, and the decision was instantly made to divert with a pan call requesting clearance to the airport 360 nm southwest.
Multiple operational conditions contributed to keep time pressure and stress in check:
- There was ample time to prepare for the approach diversion, go-around and associated procedures.
- There was ample opportunity for the pilots to review and manage potential threats linked to weather, the nature of the approach, the environment through which they were flying and even their own limitations.
Simple prevention strategies and lines of defense discussed below were followed to maintain good situational awareness, make good decisions and follow standard operating procedures (SOPs).
Prevention Strategies and Lines of Defense
The crew focused on approach preparation and was prepared for a go-around.
The following strategies are recommended in order to cope with this type of event:
- Make collective risk assessments and tactical decisions based on:
- Approach type;
- ETOPS requirements; and,
- Risk of specific threats.
- Conduct effective briefings that fully review approach procedures, profile and airplane configuration.
- Explicitly define task sharing so it is clear who is to monitor all critical flight parameters.
- Do not fall victim to press-on-itis by yielding to ATC or time pressures to rush the approach.
- “Buy” time needed to create common situational awareness among crewmembers and stabilize any stressful situation.
This incident was well managed. The crew had lots of time to think and used this time productively. Even though the captain almost decided not to divert or to delay a diversion, the collective approach helped to implement the group decision as soon as necessary:
- The crew first had to ponder whether the oil quantity loss was a real problem or just an indication problem.
- The crew then reviewed ETOPS diversion alternatives taking into account weather, airport characteristics and airplane condition.
- The crew then collectively set up decision criteria as to when to divert, based on any additional problem such as oil pressure or temperature dropping.
- When the critical additional problem became apparent, the pilots were entirely ready to implement the next step — that is, where and how to divert without pressure or haste.
Associated OGHFA Material
- Situational Awareness
- Flight Preparation and Conducting Effective Briefings
- Stress and Stress Management
- Decision-Making Training
Additional Reading Material
- Flight Safety Foundation Approach and Landing Accident Reduction (ALAR) Toolkit
- U.K. Civil Aviation Authority. CAP513, “Extended Range Twin Operations,” third edition, October 2002.
Note: Due to regulation changes and the publication of JAA GAI20, CAP 513 will remain at Issue 3 and is to be used as guidance material only for older aircraft types. For all ETOPS operational and airworthiness requirements reference should be made to Joint Aviation Authorities Document GAI20 ACJ 20X6.