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Avoidable Accidents No. 5 - Starved and exhausted: Fuel management aviation accidents

Introduction

Safe flight depends on reliable power. Despite the money and effort spent on ensuring aircraft engines are reliable, equally reliable systems are needed to ensure that engines always get the fuel they need.

This report discusses procedures that pilots can use before and during a flight to help them be absolutely sure they will have sufficient fuel to land at their destination aerodrome with reserve fuel intact. It does not discuss procedures to ensure fuel quality, such as checking all fuel drain valves for contaminants or using approved fuel, although these remain important. Nor does it discuss fuel system integrity measures, such as the maintenance of fuel filler cap seals.

The report will look at two main reasons why fuel stops getting to an engine during flight.

  • Fuel exhaustion happens when there is no useable fuel remaining to supply the engine(s).
  • Fuel starvation happens when the fuel supply to the engine(s) is interrupted although there is adequate fuel on board.

The more tanks you have to choose from, the greater the potential to make a mistake and to select the wrong fuel tank.  

Key message

  • Accurate fuel management starts with knowing exactly how much fuel is being carried at the commencement of a flight. This is easy to know if the aircraft tanks are full, or filled to tabs. If the tanks are not filled to a known setting, then a different approach is needed to determine an accurate quantity of usable fuel.
  • Accurate fuel management also relies on a method of knowing how much fuel is being consumed. Many variables can influence the fuel flow, such as changed power settings, the use of non-standard fuel leaning techniques, or flying at different cruise levels to those planned. If they are not considered and appropriately managed then the pilot’s awareness of the remaining usable fuel may be diminished.
  • Keeping fuel supplied to the engines during flight relies on the pilot’s knowledge of the aircraft’s fuel supply system and being familiar and proficient in its use. Adhering to procedures, maintaining a record of the fuel selections during flight, and ensuring the appropriate tank selections are made before descending towards your destination will lessen the likelihood of fuel starvation at what may be a critical stage of the flight. 

Conclusion

Fuel exhaustion is more likely to occur on flights when there is little flight fuel margin, that is, landing with just reserve fuel on board. In these circumstances, particular attention to detail in fuel management is warranted.

The chance of fuel exhaustion can be reduced by:

  • using more than one source of information to obtain consistent results about the fuel on board before flight
  • the use of a consistent procedure that is regularly checked to know the exact rate of fuel consumption
  • monitoring the flight to ensure that sufficient fuel will remain on board in the event of unplanned delays.
  • Fuel starvation usually happens when the selected tank is run dry. In addition to the factors relevant to fuel exhaustion, the chance of starvation can be further reduced by:
  • ensuring the pilot is fully familiar with the operation of the fuel system for both normal and abnormal operations
  • adhering to pre-flight procedures and checks to ensure the correct tank is selected before takeoff and landing
  • using a fuel log during flight to provide a record of the fuel usage from each tank
  • selecting the appropriate tank before descending to the destination and ensuring that tank has adequate fuel for landing. 
Type: Avoidable accidents
Publication date: 25 March 2013
ISBN: 978-1-74251-293-8
Publication number: AR-2011-112
 
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Last update 07 April 2014
 
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