July-August 2024

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OPERATING PROCEDURES: FULE BURN RATES

       Fuel burn rates are expressed as a unit of pounds of fuel burned per hour, per engine. This rate will vary depending on the engine used, the phase of flight and other factors. Flight Simulator flight planning and certain flight planning software will give you a total amount to be burned in the given time. Example: 6000 pounds in 2.0 hrs, or 3000 pph. Divide this by the number of engines on your DC-6 and you get 750 pounds per hour, per engine (pph/eng)..

Next, you actually  fly the trip using recommended power settings. Upon arrival, you discover you actually burned 650 pph/eng. After a few trips like this, you'll discover the average hourly fuel burn for that airplane. For the flight sim model you are flying, this method works best. Actual observed fuel burn history is always the most accurate.

What about climbs and descents? The climb power setting is determined using tables and graphs in piston aircraft, while jets simply use 100%. You'll burn more in the climb, as you use more power. The idea is to get to cruising altitude quickly. 

Descents are different in pistons and jets. Normally, piston aircraft descend at 1500 fpm, adjusting to a slightly lower power setting, to keep speed just below redline and engines from getting cooled too quickly, a bad thing for pistons. Jets, however, typically descend at 2500 fpm at or near flight idle. This will usually put them near normal maximum speed. So, despite burning extra fuel in the climb, we make up for it by burning less fuel in the descent.

Using the above table, these are burn rates I normally plan on for my flights. Minimum fuel is from departure to destination, then to an alternate, then 45 minutes reserve. This is an absolute minimum that few ever actually use. Normally, flight plan for your enroute time plus a minimum of two hours beyond that.

The big limitation to watch is your maximum landing weight. Take you estimated enroute fuel burn, add it to your maximum landing weight, and that becomes your new maximum takeoff weight. Tankering fuel isn't always a good thing. Just make sure you got a couple of hours still onboard when you land.

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