How Much Fuel Do You Need?

When I got my private pilot license I did what many new pilots do. I took family and friends up for a ride.

On a clear day with calm winds I was preparing to fly a Cessna 152 with a friend of mine who had asked to go up. This was my third or fourth flight with a passenger.

During preflight, I found that the fuel tanks were not full but they appeared to be near the top. I did not use a fuel stick to measure the exact amount but I reasoned that it was enough. This was a big mistake. I considered asking for fuel but I didn’t want to bother the line service guys.

We departed and flew over our houses and to a nearby airport. Finally, we decided to return, although I very easily might have continued flying. Fuel was the farthest thing from my mind.

We landed and put the plane away. But that’s not the end of the story.

A few days later I was called into the Chief Flight Instructor’s office. He informed me that the fuel records showed that I had less than 20 minutes of fuel left when I landed.

Landing with this small reserve can happen on a well planned out flight if the winds change, but it was particularly dangerous in my case because I was not aware of the urgency of the situation!

Never Again

I learned a lot from that experience. I never flew again without knowing exactly how many gallons of fuel I had onboard.

In addition, I set personal minimums in excess of the legal minimums.

If you feel like you are bothering line service with a small fuel request then say something like “Hey, this might only take 2 or 3 gallons but I want to be totally sure.” If the line service technician isn’t a complete sociopath then they will understand and be more than happy to help you.

The Rules

The legal minimum amount of reserve fuel that you can depart with is enough to fly for 30 minutes after you reach your planned destination. If you are flying IFR or at night, then you need 45 minutes of reserve fuel.

I very strongly encourage you to use a safer personal minimum. The fuel gauges in many light aircraft are very bad and give you little idea of your current fuel quantity.

I use a personal minimum of 1 hour for day flying and for night or flight in IMC I want to have a lot more than that, sometimes double the required fuel.

Fuel exhaustion is the most common cause of engine failure. So by following a safe personal minimum and taking no chances with fuel, you can significantly decrease your odds of having to face this emergency.

Consider these questions:

  • Do you have a personal minimum for fuel?
  • Will line service really be “bothered” if you ask for more?
  • Did you verify the fuel level yourself after getting a top off?
  • Did you check that your fuel is clean and of the correct type?

 

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