(June 2011) The captain had completed an entry of the navigation log after passing the previous oceanic waypoint. The FMS, utilizing a series of inertial navigation systems along with two GPS receivers, was tracking the assigned course to an accuracy that was no wider than the cockpit of the 777. The digital display of the altitude pointer indicated that the airplane had fluctuated no more than five feet. The ATC page of the comm screen verified that Shanwick Oceanic had automatically received the position report. No voice calls were required. Life was good.
Well … right up until the moment that the EICAS (engine instrument and crew alerting system) screen annunciated an amber message: “fuel imbalance.”
Anticipating the captain’s request, the copilot pressed a button on the eyebrow of the instrument panel. The fuel synoptic, a schematic diagram, displayed on the center pedestal screen. The diagram confirmed the reason for the EICAS message. Fuel from the right main tank was disappearing faster than from the left main tank. Not good. But why was it happening?
The EICAS now displayed a prompt for the fuel imbalance checklist. The copilot selected the appropriate electronic page. The checklist procedure was short, but it immediately led in a new direction: Is it a fuel leak?
As the copilot initiated the fuel leak checklist, the captain unclipped the intercom handset and pressed the code to call the relief pilot, who was on his rest break in the crew bunk. When the relief pilot groggily answered, the captain explained the problem and requested that he visually inspect the engine and right wing for any evidence of a vapor stream.
In a matter of minutes, the interphone chimed in the cockpit. The captain placed the handset back on his ear and listened to the serious tone of the relief pilot’s voice. The relief pilot confirmed a vapor trail exiting from the right engine.
The captain re-cradled the handset and studied the lower EICAS screen. The copilot had reached a decision item in the checklist. And the decision wasn’t pretty. The right engine had to be shut down. The flight was more than one hour from the nearest suitable alternate.
The captain glanced out the left side window. For a brief second he considered the inky blackness of the North Atlantic on a February afternoon. The blackness was interrupted with tufts of white, etching a checkerboard mosaic onto the churning sea. The ocean was uninviting even from the height of 38,000 feet. For all the state-of-the-art technology stuffed into a long aluminum tube, none of it would make a difference if the airplane were forced to transform itself into a very unseaworthy ocean liner. The captain would have to make a decision that directly affected the safe outcome of his passengers and crew. The decision could very well define his career and the salary that he had earned in his lifetime. No big deal.
Fortunately, the rules of the road were on the captain’s side. The flight was operating under ETOPS (extended twin engine operation) procedures. In the North Atlantic, a twin-engine jet airliner is required to remain within 180 minutes in still air from an alternate airport with one engine inoperative. The alternate airport must have the capability to handle the arrival of the particular airplane type. The fuel on board to reach the alternate(s) at the point most distant on the route must allow for the worst-case scenario of an engine failure, an explosive depressurization or an engine failure accompanied by an explosive depressurization. The parameters also include, but are not limited to, consideration for wind, the use of anti-ice, airborne APU operation and engine performance degradation.
By theory, the flight should not face fuel exhaustion — as long as the leak stops, of course. With an engine shut down, the captain is well aware that he must depart the assigned track. Why? The airplane cannot sustain an altitude of FL 380. It will have to begin a slow drift down. A glance at the engine-out page of the FMC indicates that the airplane is capable of maintaining
FL 220. Now what?
Specific procedures must be followed. Although obtaining a clearance through the appropriate oceanic controlling agency is the best solution, there is no time. In that case, the rules require that the airplane be turned more than 45 degrees from the original course, preferably in the direction of the alternate. But which alternate?