December 1, 2007
My memory of Pilgrim Airlines Flight 203 resurfaced recently after a report about an unfortunate pilot who ditched and drowned near the shoreline of Lake Michigan after running out of fuel.
The Pilgrim Airlines Twin Otter ditched into Long Island Sound just five miles short of the Groton-New London, Connecticut, airport on February 10, 1970. The two pilots and three passengers perished in cold New England waters. I had taken my flying lessons at Groton the previous year; I attended college in nearby New London, and one of the three passengers was a member of the accreditation board that had just visited my college. Despite the lapse of years, the specter of two pilots staring out at the dark, cold surface of Long Island Sound when the engines stopped still perfectly captures the horror and helplessness of running out of fuel in an airplane.
Every year pilots let their fuel situation get away from them. In 2006, there were an average of about two flights per week that ended in fuel-related accidents. Many other flights end in near accidents when a dwindling fuel supply proves just enough to get to a runway. And losing control of the fuel situation happens to both experienced and inexperienced pilots.
Yet managing fuel may not get a lot of practice in everyday flying. A one-hour local flight with a four-hour fuel supply demands very little thinking about fuel. When traveling by light airplane, the human body protects against fuel exhaustion as pilots and passengers weary long before the typical light aircraft uses up full tanks of fuel. Whenever there is a lot of extra fuel on board, keeping an eye on the gas gauge suffices as fuel management.
Planning a maximum-range flight—or a flight with a partial fuel load or a flight into difficult weather conditions—demands a far more careful appraisal of fuel requirements. More precise and disciplined thinking is needed for these flights. Fuel awareness is the collection of mental habits that pilots form around the problem of managing fuel. And, just like other habits, the way pilots think about fuel results from practice.
What kind of practice develops a pilot's fuel awareness? A good starting point is an active habit of appraising the fuel available. Knowing the precise amount of fuel on board offers special challenges for pilots of small aircraft because of limitations in the accuracy of fuel-quantity indicating systems. Tanks that are carefully fueled provide the most accurate fuel-quantity information a light airplane pilot will ever have, but, as soon as the engine is started, fuel remaining becomes an estimate that is subject to a degree of error. Pilots can refine their skill at estimating the fuel remaining by practicing awareness of how the fuel taken before and after a flight compares with the gauges, the expected fuel burn rate, or a fuel-flow computer (if installed). Knowing the fuel on board, with an appropriate allowance for error, underpins all the other habits a pilot uses to manage fuel.
But what other habits and cues keep pilots clear of a fuel dilemma? Are pilots aware of the seductive nature of uncertainty about their fuel situation? A look at a brief history of Pilgrim Airlines Flight 203 provides a good backdrop for a discussion about the habits of thinking about fuel.
The Twin Otter, operating as a scheduled air taxi flight, departed Groton at 4:16 p.m. for the 89-nautical-mile flight to New York's John F. Kennedy International Airport with two hours and 21 minutes of fuel on board. Low and worsening IFR conditions existed all across the route. The flight received its first holding clearance just 17 minutes after takeoff. All told, the captain committed one hour and 21 minutes of the Otter's fuel supply on expectations of landing at JFK. With one hour of fuel remaining, the flight was about to get off the holding stack and onto the approach when the Otter's transponder failed. The New York approach controller told the flight that it would have to wait about 15 minutes more until he could work it onto the approach as a non-radar target. At this point, the captain chose to divert the flight and asked for a clearance to New Haven, Connecticut. After eight minutes of coordination with Westchester approach, the flight was cleared to a fix short of New Haven. There, the captain accepted 17 minutes of holding while a Cessna 182 shot the non-precision approach ahead of him. As the flight held, New Haven weather deteriorated rapidly below minimums. Informed of the change in conditions, the captain nonetheless began the approach. Fuel remaining at this point was 23 minutes. The flight missed the approach at New Haven, which led to a desperate attempt to reach home base in Groton. The captain descended to 100 feet over Long Island Sound to get below the overcast before running out of fuel at approximately 6:37 p.m. At the point where Flight 203 exhausted its fuel, the Twin Otter would have needed about three minutes, or five gallons, of fuel to reach the runway in Groton. The captain never declared an emergency.
Opportunities to prevent a fuel-management accident come in stages that begin on the ground with preflight planning. Pilots may think about the fuel part of a flight plan in terms of the legal requirements, but this is an unfortunate habit. Analysis of the flight, and not the legal requirements, is the basis for an effective fuel-planning habit. As was the case for Pilgrim Airlines Flight 203, the fuel needs determined by careful analysis are frequently much greater than those required by regulation. For Flight 203, the accident board determined that Glen Falls, New York, 160 nautical miles north of JFK, was the nearest suitable alternate, and the flight departed without the legally required fuel to fly from Groton to JFK, on to Glen Falls, and thereafter for 45 minutes. Although there was no evidence that the captain considered the fuel needed to reach a legal alternate, even this amount of fuel (less than 30 minutes more) might not have been enough to spare the captain an invitation to disaster.
A legal fuel plan would have provided Flight 203 with fuel to get to Glen Falls, but it would not have required an allowance for holding at JFK. Without holding fuel, the captain still would have been thrust into an immediate and difficult decision—a choice between diverting to a very distant alternate or burning alternate fuel on the gamble of making it into JFK. The fuel plan should aim for success, which means incorporating fuel for foreseeable risks. Holding for JFK could not have been a surprise for the Otter captain. The choice to begin a flight without fuel to accommodate reasonable risks is a special invitation to entertain difficult fuel decisions.
A fuel plan can be either detailed and written or simply an idea, but in any case, a good plan anticipates an allowance for fuel needed to cover a distance or mission plus fuel needed for contingency factors. These factors include all of the imaginable risks and some allowance for the unimaginable. Imaginable risks may include the following: fuel for ground delays; fuel to reach a safe alternate; fuel to hold; and fuel for vectors, reroutes, weather avoidance, or other ATC delays. All of these are common allowances used by airlines operating in busy ATC environments. Some or all of these factors will be appropriate for small aircraft on some flights. In addition, small piston-powered aircraft must always allow for two contingencies that rarely affect large or high-performance aircraft to the same degree. These include allowing for a headwind component that exceeds the forecast, and allowing for a higher-than-normal burn rate because of variability in mixture management.
What is reserve fuel? Reserve fuel is the minimum fuel required by the FAA for landing, and not fuel available for headwinds, holding, or other predictable contingencies. Pilots should consider minimum fuel an allowance for true surprises. Pilots can be surprised by a gear-warning light at the final approach fix, the mower that breaks down in the middle of the runway, the pilot-controlled lighting that fails to work, and many other real-life occurrences. Minimum fuel also considers the special difficulties of ensuring a continuous flow of fuel when a small quantity of liquid occupies a much larger container. Imagine what 45 minutes of fuel looks like when divided among two or four tanks. Many aircraft flight manuals limit pitch attitudes and the type of maneuvering that can be accomplished in a minimum fuel state. For these reasons, minimum fuel is not all-purpose fuel. Finally, what a pilot holds as minimum fuel also acknowledges limits in the fuel-quantity indicating system.
A detailed and carefully considered fuel plan improves the odds of success and makes it easier to tell when things go awry. But, as hundreds of yearly airline diversions and returns to the gate can affirm, even a good fuel plan is no assurance of success in reaching the destination or even a planned alternate. But neither does a poor plan automatically commit a pilot to tragic consequences.
A pilot must be able to make difficult in-flight decisions about fuel the same way he must be able to detect and react to changes in the weather. The single most important mental habit that a pilot can develop with respect to fuel is the practice of continuous active appraisal of the actual fuel situation against the flight that was planned or envisioned. This appraisal must include a reassessment of risks and the availability of fuel to cover those risks. Unlike a wall of dark cloud and lightning, a deteriorating fuel situation may present itself in no stronger form than a recurring sense of doubt or uncertainty. Fuel-related accidents involve a pilot tolerating a prolonged uncertainty about fuel and a gradual surrender to events outside of his control.
Pilgrim Airlines Flight 203 was not consigned to tragedy by a lack of planning alone. After all, the captain had a plan formed by the habit of many other successful flights from Groton to Kennedy. He planned to fly toward New York, hold for a while, and land. This plan might have become questionable as holding was extended. There is no way to tell when, in the captain's mind, he first experienced doubt about his arrival at JFK. As the captain held the Otter in New York airspace, he gradually surrendered control over his fuel situation until he had placed the flight in a complete state of dependence on ATC. This dependence was harshly punished when his transponder failed just as the promised approach clearance was in hand. The most significant error committed by the captain was his failure to recognize that the events of that evening gave him something that he had not anticipated. In a lack of active appraisal of his fuel situation, he surrendered to circumstances.
Despite inadequate planning and the surrender of options by enduring a long hold, the captain of Flight 203 could have restored control of the flight by declaring an emergency. Why did the captain fail to recognize a fuel emergency when his situation was perilous? The most difficult fuel awareness habit is to recognize the beginning of a low-fuel emergency as a loss of control of the fuel situation. There are some good reasons for this difficulty.
The low-fuel emergency has no prominent signaling feature. Consider the abrupt and startling features of an engine failure by comparison. With the sound of clanking parts, all of the mental resources of the pilot are brought to bear on a set of rehearsed activities. But rather than drawing a focus to the problem, uncertainty about fuel divides the pilot's attention in a debate between the prospect of continuing on one hand and uncertainty on the other. As the uneasiness mounts, the nearness of a safe landing offers renewed hope—a foot race ensues between hope and dread. Not until the Pratt & Whitney PT6 turbines quit on the Otter, first one and then the other, did the last vestiges of hope abandon the captain of Pilgrim Airlines Flight 203 to a cockpit with only the sounds of the rushing slipstream with a faint glow of the shoreline just beyond reach. For the captain of Flight 203, and for many other pilots, the emergency could not be definitive until then.
Fuel exhaustion is a self-induced accident, not an emergency. When it comes to fuel, unresolved doubt about whether a flight can be completed is the emergency. Unresolved doubt demands immediate action and, when this immediate action requires the help of others, a declaration of emergency must follow. The quality of the fuel plan—its detail, whether it is put in writing or just a rough mental construct, and whether the plan has allowances for contingencies—determines how wide the door is left open for the entry of uncertainty. A vague plan is one by which uncertainty enters easily and demands a heightened sensitivity to unexpected events. To start or extend a flight with a fuel uncertainty is to take a temptress by the hand.
When it comes to fuel, the first doubt is the best chance to avoid a serious problem.
Chris Burns is a recently retired US Airways Boeing 737 captain. He has owned and flown general aviation aircraft for the past 35 years.
Aircraft Power and Fuel,
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