What is the typical fuel consumption of a 737 in MPG?

Question

What is the typical fuel consumption of a Boeing 737 in MPG?

Answer 1

The following table shows the long range cruise control data for a Boeing 737-800 (source: FCOMv1 Performance Inflight - All Engine PI.31.2):

Let us consider a typical cruise at FL370 with a weight of $ 65 \, \mathrm{t} $. The table tells us that the fuel flow per engine would be:

$$ \mathrm{FF} = 1231 \, \mathrm{kg}/\mathrm{h} $$

We are interested in the fuel consumption per distance, not per time. The table tells us that we would fly at Mach $ 0.793 $. At an altitude of $ 37 \, 000 \, \mathrm{ft} $ the speed of sound would be $ 295 \, \mathrm{m}/\mathrm{s} \approx 574 \, \mathrm{kt} $ assuming ISA (International Standard Atmosphere) conditions. This gives us the cruise TAS (true airspeed):

$$ \mathrm{KTAS} = 455 $$

The resulting fuel economy is then:

$$ \frac{2 \times \mathrm{FF}}{\mathrm{KTAS}} = 5.41 \, \mathrm{kg}/\mathrm{NM} $$

You asked for MPG (miles per gallon), so we need to convert that mass of fuel into a volume. The density of jet fuel depends on temperature. Assuming you refer to the volume on the ground, let us assume $ \rho = 0.820 \, \mathrm{kg}/\mathrm{l} $ for Jet-A. This gives:

$$ 1.51 \, \mathrm{gal}/\mathrm{mi} \; \Rightarrow \; 0.66 \, \mathrm{MPG} $$

All of this assumes no wind. If there is a $ 50 \, \mathrm{kt} $ headwind for example, the ground speed (GS) would reduce accordingly ($ \mathrm{GS} = \mathrm{TAS} - \mathrm{Headwind} $). Using this instead of KTAS in the equations above gives:

$$ 50 \, \mathrm{kt} \; \mathrm{Headwind}: \; 0.59 \, \mathrm{MPG} \; ; \; \; 50 \, \mathrm{kt} \; \mathrm{Tailwind}: \; 0.73 \, \mathrm{MPG} $$

Note: This is for the entire aircraft. If you are interested in fuel economy per seat, multiply the MPG with the number of seats (189 is the exit limit for a 737-800).

Answer 2

It's not fixed, some of the variables are:

1. Which 737 family and variant
2. Flight (air) distance, which is affected by wind
3. Passenger load.

In general, for any current jet-liner's fuel mileage, I recommend Wikipedia's article on aircraft fuel economy. The figures are well-sourced, and structured nicely. Just remember to divide the mpg values there with the number of passengers from the same row if you are more interested in the whole plane.

For a 737-800 with 162 passengers on a 1000 NM trip, it's 96 mpg per passenger, or 0.593 mpg for the whole plane.