Gasping for Gas

Many fuel exhaustion accidents share three common mistakes


The return trip from mid-state New York to Nashua, N.H., was being made with some urgency. The pilot had an important meeting to attend. The meeting became the last thing on his mind, however, when the engine coughed to a stop only part way home.

His very first thoughts: Oh damn! Im going to splatter myself among the trees below and kill myself! I can just hear my friends at the funeral. He seemed to be a pretty smart fellow, how could he do something so stupid?

After his initial shock at the silence, he became focused on the problem at hand. Rock the wings, theres always some fuel left in the tanks. The engine sputtered a few minutes and then quit again. He spied a small field he would have to use as his emergency landing site, but the only way to get through it was through a stand of trees. He remembered a magazine article he had read long ago: If you have to put a plane down in the trees, pick two big ones and fly between them. The wings will dissipate some of the energy without causing damage to the cockpit.

Miraculously the 40-year old, 200-hour private pilot did just that. With both wing tips damaged, he planted his Cessna 150 onto the ground in a field that was no more than 200 to 300 feet long. The nose wheel dug into the soft turf, and snapped in two. Seconds later the pilot jumped out of the plane and checked for injuries and damage. The injuries were minor, the damage significant. When the FAA inspector investigated the accident, he said of the between-the-trees-maneuver, Ive heard it suggested. Ive never seen it work until now. As for the meeting, the pilot was late, very very late. But at least he lived to fly again.

Fuel starvation accidents are perhaps the single most preventable type of accident in aviation. The familiar psychological aspects, most notably get-home-itis are compounded by the Three Ms of running out of fuel: misinformation, mismanagement and mechanical problems.

The Cessna 150 pilots accident combined portions of all three elements to create the problem, but often one factor is enough to create havoc. This time it was a private pilot on a pleasure flight, but when any one of the Three Ms arises, highly experienced professional pilots are equally at risk. Although the causes themselves seem relatively easy to explain, the reasons why those causes are allowed to snowball into accidents are much more complex. What is most compelling, however, is that in almost every instance, the pilot or pilots involved had a means by which to recognize and resolve the problem before it became unmanageable, yet each ignored it until it was too late.

M Number 1
Misinformation, believing something to be true that simply isnt, can occur in many forms and for many reasons. Our private pilot in question, even though he owned the Cessna, thought his plane was equipped with fuel tanks that carried 26.5 gallons of fuel per side. In reality it carried only 22.5 gallons in each tank. On the other end of the equipment scale, an air carrier crew used to operating with liters calculated the fuel needed for their first flight in a new aircraft based upon that measurement. Unfortunately it was serviced in the United States with gallons. Somewhere the conversion went astray and the aircraft ran out of fuel short of its destination.

Another pilot told the ramp attendant to top off all the tanks and, even though the pilot signed a bill clearly indicating not enough fuel had been pumped to fill each tank, he took off without the auxiliary tanks filled. In what is perhaps one of the most unusual instances of misinformation, a student turned back the panel clock in anticipation of a time zone change during a cross-country flight with his instructor. The instructor didnt notice the action, and thought they had one more hour of fuel when the mill stopped turning. They didnt get where they were going.

M Number 2
Mismanagement, though containing a certain amount of misinformation as well, is essentially knowing the right things but arriving at an incorrect conclusion due to faulty assumptions somewhere along the way.

One pilot expected a fuel burn of four gallons per hour, he got six. More than just a few pilots crash-landed prematurely having run their engines dry only to find a lots of fuel in the tank on the other side of the airplane. Just about as many calculated a flight for a given set of weather conditions, only to find a stronger-than-expected headwind. One in particular blamed ATC for not knowing that an 8,000-foot altitude assignment would hurt his aircrafts performance to the degree that he ran out of fuel. Sadly, most victims had strong indications that running out of fuel was a distinct possibility long before it happened.

M Number 3
Finally, mechanical problems cause their share of fuel starvation accidents. Unfortunately for most pilots, the situations caused by mechanical failures were neither terribly unusual nor totally unexpected. Leaking fuel drains repeatedly appeared as the culprits in dozens of accidents. More often than not, the pilots had been aware of the problems. Inaccurate or almost totally inoperative fuel gauges took their share of the blame, along with the pilots who knew of the existing conditions long before their final flights ever took place. In a more unusual situation, a fuel bladder partially collapsed, causing the pilot to see what he thought was more fuel than actually existed during his visual inspection of the tank. But regardless of the particular malfunction that led each pilot to land short of the intended destination, each generally had a strong indication that all was not as it was supposed to have been.

Pilots all know that running out of gas is bad. They certainly realize that the engine stopping can lead to tragic results. The questions are obvious: Why do so many run out of fuel and what can be done to avoid the tragedy that lurks there? The answer is surprisingly simple: Pilots who use bad judgement shouldnt do that anymore. The problem is that the simple answer hasnt fixed the problem. For reasons that too often defy explanation, pilots continue to run out of fuel.

Gauging the Answer
One school of thought is that, from the very beginning of a pilots training, the proper emphasis is never put on fuel-related issues, and there are many. The complexities begin to appear with something as simple as a fuel gauge.

FAR 23.1337(b) requires there to be a means to indicate to the flight crewmembers the quantity of fuel in each tank during flight. Yet subparagraph (1) states, Each fuel quantity indicator must be calibrated to read zero during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under FAR 23.959. In short, the only time a fuel gauge must be accurate is when there is nothing left to use. If you bet your life on the accuracy of the gauges anywhere between full and empty, the odds are good that you will lose.

But the history most pilots bring to flying encourages them to do just that. The history is the automobile. Who has not driven 10, 20 or 30 miles with the gas gauge needle pegged on empty, only to arrive at a gas station in time to fill er up? In report after report, pilots did the same thing in their airplanes. They knowingly overflew at least one or two airports on their way to an off-airport landing, just knowing that the fuel gauges werent going to really be empty as soon as they showed empty.

The accuracy of the E on the fuel gauge runs counter to the otherwise built-in forgiving nature and margin-for-error design of todays general aviation fleet, making it easy to understand how pilots can lead themselves to believe the worst is not yet to come. Why else would a pilot 1) depart with one tank empty and the other indicating full or 2) depart with enough fuel to fly 50NM but only make it 30 NM? Then theres the 10-minute night flight I personally witnessed as an all-too-complacent right seat pilot/passenger in which fuel became a concern immediately after takeoff. Pilots, it seems, have not only come to expect reliability from modern machines, but foolishly depend upon it.

Gauges arent the only error-prone part of the fuel system. Often pilots demonstrate a marked ignorance of how the fuel system components work together to ensure that the engine continues to run. In one incident a pilot who had been doing aerial survey work started to spiral down for a return to the airport when the engine promptly quit. Among his efforts to restart the engine was turning on the boost pump. The engine momentarily restarted, then quit again.

Later investigation revealed that uncoordinated flight may have displaced fuel in the tanks away from the uptake line, and the boost pump most likely flooded the engine. What works in one airplane under certain circumstances doesnt necessarily work in another or even in the same aircraft under different circumstances. Properly learning the differences is essential to accurate fuel management.

Learning the Lessons
The good news is that, regardless of which of the Three Ms of fuel starvation is being addressed, many of the solutions to the problems are relatively simple to understand, but not necessarily easy to overcome. Each involves a certain amount of learning, experimentation and diligence. But the resulting rewards are ample.

For starters, look to the airline and professional pilots who seldom, if ever, run out of fuel. There are, after all, many similarities in that they fly planes, just like general aviation pilots. Their planes use fuel – and quit flying when the fuel ceases to be available.

But the similarities are overshadowed by the questions general aviation pilots generally dont ask, but that are routine for the pros.

For instance, how often do G.A. pilots fly to the legal limit of fuel consumption? How often is a flight made beyond the area wherein weather may have a real impact on the completion of that flight? Or how often do they fly IFR in the system and how often are they confronted with ATC altering the flight plan to the degree that fuel consumption is significantly affected? How accurately do they know the consumption figures for their planes in a variety of different conditions? Maybe most importantly, to how many of the above-noted questions do they know the exact answers, not just approximations?

One of the first things I do with a new car is purposely drive it until the gas gauge is on empty and then fill the tank to see how much was really left. I dont do that with a new airplane I fly, so usually I dont know how accurate the gauges are. I can accurately calculate the fuel consumption, but I am among the many who have to rent airplanes and get a different one almost every time we fly.

If the truth were known, the FBO or other owner probably has a more accurate and complete record of fueling and time flown for those rentals than many owner/pilot operators have. We have only to ask to see the records and then calculate the per hour fuel consumption for that plane, based upon a history that probably includes at least the last 100 or 200 hours of operation. It likely runs the gamut of weather conditions and pilots who lean aggressively or not at all. But its a reasonable place to start.

Airline and charter operators are required to keep routine records of engine operations throughout the course of each flight. Were general aviation pilots to do the same, most would not only notice irregularities in fuel consumption and engine performance at the earliest possible stages, but each would also probably have a significantly accurate indication of their airplanes performance in each phase of flight for a wide variety of conditions.

How does spark plug wear impact fuel consumption? How much fuel should the plane burn on a flight at 6,000 feet with an outside temperature of 5 degrees Celsius and a climb at 25 inches of manifold pressure and 2500 RPM to that altitude and a cruise descent at 160 knots? Most pilots dont know the answers, but they should. Taking a few minutes to record engine indications periodically and accurately record fuel used at the end of the flight is time well spent.

Knowing When to Quit
Understanding the system also impacts how well pilots manage fuel. Particularly for IFR pilots, the system will undoubtedly have major impacts. Steve Berardo, a Gold Seal Flight Instructor with more hours instructing than many pilots have flying, looks at the whole issue of fuel management in a special way.

If you really think about it, general aviation pilots flying IFR, on average, have about a 50 percent chance of completing a flight as planned, Berardo says. Either because of weather, traffic or ATC procedures, actual fuel consumption can often vary greatly from planned consumption. I dont think the typical general aviation pilot is always prepared for the consequences.

For that reason, Berardo teaches a procedure that, though simple in concept, begins to address the problem of running out of fuel. He calls it using WOG time. Before each flight, Berardo has his students calculate an accurate estimate of fuel burn and determine how long they can fly and still have a legal reserve. At engine start he then has them calculate and record their WOG time – or Wheels on Ground time – with that time written down and in plain sight in the cockpit,

Berardos students know that when WOG time draws near it is time to be looking for a place to land, regardless of whether it is the intended destination. If, from the beginning of a flight we accept that there is about half a chance we will arrive at our original destination on time and in the manner planned, it becomes much easier to use a WOG time to go somewhere else.

For my own instrument students, I advise calculating the distance to the destination airport as planned and then add 30 miles for vectoring from ATC. Seldom, if ever, does a pilot on an instrument flight get to fly a straight line from one airport to the next. Carrying enough fuel to handle the typical diversion isnt a luxury, it is a necessity.

Everybody has One
Virtually every pilot who runs out of fuel understands the lunacy of doing so and offers an excuse. The excuses offer testimony to the fact that the problem wasnt really unexpected. The narratives of accident and incident reports are littered with comments like, I noticed the gauges were showing more fuel burn than was normal. I overflew two airports in an attempt to make it to my destination. I knew the gauge wasnt working. Fuel stains indicated that leaking had been occurring for sometime. The list goes on and on.

Without trying to delve into the specific reasons pilots allow such situations to develop, there is a solution that would have helped in most cases. Robert Mudge, a retired Delta captain and founder of Cockpit Management Resources, a company that has done much to bring cockpit resource management to general aviation, has developed a concept called the Challenge and Response Operational Environment.

The most basic tenet of CROE is a two-step process: 1) React conservatively and 2) Validate. In its simplest form, CROE means that anytime a pilot suspects a problem is developing that may threaten the safety of a flight, he must take the most conservative action available until the situation is resolved. If the fuel gauges seem to be indicating greater usage than was anticipated, the conservative response is to land at the first practical opportunity and examine the situation.

If there is water in the fuel strainer, for example, dont just drain what seems to be enough out of the tanks. Drain the tanks until there is no water left, even if it means draining all the fuel out of the tanks. Fuel is cheap compared with an off-airport landing.

In one instance, investigators on the scene of a fuel starvation accident determined there were six gallons of water in the planes fuel tanks. In another, a pilot took off with known water in the tanks. The subsequent accident investigation revealed the liquid in the engine fuel system was 100 percent water.

If there is a known mechanical problem, dont assume the manufacturer has built in tolerances that allow the engine to continue operating. Get it fixed. Reports of known problems with fuel caps, tank vents, fuel gauges and leaking drains repeatedly appear in fuel starvation accidents. The expense may seem great, but the ultimate cost of doing nothing could be unimaginable.

As is often the case, the pilot of the Cessna 150 who survived his fuel starvation ordeal had more than just a meeting affecting his judgment. The purchase of his airplane was not without sacrifice and not without compromise. It was a major expense, and the 150 was certified to use auto fuel to offset some of that expense. The pilot knew that if he stopped for fuel instead of making it to his home airport, the cost of refueling would be significantly more than if he could get to his cans of auto gas back home. If he had made it he would have been right, but of course he didnt.

In what was one of the most tragic accidents involving running out of fuel, a pilot took his wife, son and two friends out for a sightseeing ride in his Cessna Cardinal. Despite known inaccurate fuel gauges, they took off with the aircraft log indicating it had flown 3.4 hours since the last refueling. After 1.2 hours of enjoying the mountainous scenery, the engine quit. The two friends were seriously injured. The husband, wife and son died.

While running out of fuel was no doubt an unexpected event, it shouldnt have been. With the proper emphasis on learning as much as possible about fuel systems and fuel usage, there should be few surprises. In a very real sense, misinformation, mismanagement and mechanical failure are often not separate categories of fuel starvation accidents, but rather a continuum in which one often leads to the other, which leads to the other, which ultimately leads to a premature end to an otherwise well thought-out flight.

The only effective defense is to rethink how much we know about the system that fuels our plane, how accurately we can predict fuel consumption in a host of different situations, and how quickly we can become alerted to unusual or unfamiliar indications that warn of impending trouble. The methods and information to eliminate almost all of the fuel starvation accidents are available. It starts at the beginning of a pilots training, but the learning process should go on indefinitely.

Running out of fuel may be the cause listed on the accident report, but lack of adequate knowledge is the real reason behind the problem.

-by Milovan Brenlove

Milovan Brenlove is an Assistant Professor of Aviation at Daniel Webster College, a flight instructor and a former air traffic controller.


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