Fuel Exhaustion - Are We Set Up To Fail

Our expectations are so low for aircraft fuel level gauging systems, They are hardly ever relied on.

In fact when we educate new pilots this is typically what is said.

• The first one is taken from the AIM

FUEL REMAINING—A phrase used by either pilots or controllers when relating to the fuel remaining on board until actual fuel exhaustion. When transmitting such information in response to either a controller question or pilot initiated cautionary advisory to air traffic control, pilots will state the APPROXIMATE NUMBER OF MINUTES the flight can continue with the fuel remaining.

All reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance for established fuel gauge system error.

• The second one from the Irish Aviation Authority

Aircraft fuel gauges can be notoriously inaccurate so it more reliable to “dip” the tanks to establish how much fuel is onboard. However, make sure that your dipstick is calibrated to suit your aircraft type, the aircraft is parked on level ground and the fuel level has been allowed to stabilise before you dip.

• The final one from AOPA  Flight Training Magazine

Use the clock - not the fuel quantity indicators on the panel - as your fuel gauge. In other words, plan and track your fuel consumption based on endurance, not range. Unlike range, endurance is not at the mercy of winds. Besides, those fuel gauge indicators probably won't be very accurate except when they read empty - a setting you should never see. 

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In fact the pilot mantra given to prevent Fuel Starvation and Exhaustion is  "PREFLIGHT, PREFLIGHT, PREFLIGHT  

So what do we normally look for in a PREFLIGHT inspection - tires, brakes, oil level, security of the flight controls, condition of the prop, security of the fuel caps.   Basically all the stuff you can't check in flight.

The implication here is - you have only one chance per flight to check your fuel level - & that one chance is at your PREFLIGHT inspection.  - If you avoid that critical step, you are flying on borrowed time buddy.

Here is the rub  - you are supposed to be able to monitor your fuel level throughout your time in the air.

Another Pilot Mantra could just as easily be be "INFLIGHT, INFLIGHT, INFLIGHT.  That INFLIGHT scenario would be the pilot comparing anticipated fuel level, to actual indicated fuel level.  This would be the pilot vigilance stuff, you know the cross checks of fuel remaining from the calculations to what is onboard.  

Fuel Gauges are required instruments and found on all powered aircraft - So yes the FAA actually expected them to work.  ---  I bet you are surprised.

You are, by design, supposed to be able to see how much fuel you have at any time while you are in the air.   It is the law, it really is, and it really is a good idea.

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In 1974 (yes that long ago) the NTSB initiated a study on Fuel Starvation,  in this study,  they found that there were some aircraft that rarely had a fuel starvation event,  and they also found some aircraft that were prone to the issue - Most aircraft as you might guess were average in this regard.

SO what this study pointed out, it didn't really come right out and say it,  but it was pretty clear that fuel exhaustion wasn't just a pilot thing  - 

If it were, pilots being human - some good, some bad & most of them average would equally suffer fuel starvation in any aircraft.  It would not matter which aircraft you flew.

An average pilot in an average aircraft might have a fuel starvation event - but not really that likely.

An average pilot might never experience a fuel starvation in "X" model aircraft, but that same pilot might be assured of a high probability of fuel starvation if he flew "Y" model aircraft 

As General Aviation is slow to change - some of those aircraft are still in production.  In fact some of those aircraft in the study are still flying.

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So what did the Aircraft Manufacturers recommend in the 1974 Report:

• Two manufacturers recommended a separate Low Fuel warning system. 

• One manufacturer recommended that a more accurate and reliable fuel level system be developed. 

• One manufacturer believed that a "one tank system" would be beneficial.

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So what did the NTSB recommend in the 1974 Report:

• Specification for a low fuel level warning that would operate independently of the existing fuel gauging system.

• Specification for a more accurate type fuel quantity gauging system. 

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That was 40 years ago - so 

Where Are We Now! 

I am guessing from the picture,  that we are still on the road to find a solution.