45 min fuel reserve for a cross country trrip?

Question

Hello I vaigly remember the formula for flight calculations for a cross country flight fuel useable / fuel used *3 * 60 is this the correct formula for a 45 min reserve?? my dad and I used to fly long ago but due to age and money not anymore sooo I took up flight simming instead not the same but it is ok. So is the above formula correct?? Thank You:)

* 8 hours ago

TOT FUEL/USED *3*60-45

Answer 1

OR:  Feul flow in gallons per hour x .75

That seems a little easier.

Really, you should be calculating this long before you take off, not en route thinking things about how much fuel you've used and making calculations based off of that.  All fuel planning should ideally be done before the fuel guy unhooks his hose.  Its tough to get up there and realize "hmmm I should have more gas than I do..."

Answer 2

I am unfamiliar with this formula but as mentioned go by what the POH or your personal experience with your aircraft tells you. Obviously if you fly different aircraft, you must go by what the POH tells you. I can plan on burning an average of 10g/hr in mine and I therefore know that I must have at least an extra 7.5 gals on board for a 45 minute reserve.

Answer 3

Use the fuel consumption graphic in the back of the POH.  Find the hourly consumption rate under the conditions where you will be flying, and multiply by 0.75.

Answer 4

Looks to me like a formula like that would have to adjusted for different planes and different throttle settings, since no two will end up with the same reserves.  

You say fuel usable/fuel used.....is that in gallons?

The only way to know how much you've burned is through time or if your plane has a fuel flow meter.  I always go by time......the plane I fly has 5.5 hours of cruise at 9.25 gph to burn the tanks dry.  If I want to keep 45 mins. of reserves, I know I can't fly past 4.75 hours.  Although that's pushing it.  My personal max is 3 hours before it's time to drain my bladder and add more fuel.

Figure out how much your plane burns by the hour, then go conservately by time.  (always assume your plane burns more than it does, just it case.....)

Answer 5

Huh? Don't have a clue what your formula tells you. But if your asking how many gallons do you need as a 45 min reserve that's super duper easy. Figure your galons per hour fuel burn at normal cruise. Multiply that number by .75 hours (45 min). There ya go. Put on board enough fuel to start, taxi, runup, takeoff, climb, cruise, descend, make an approach and land. Now add the reserve number you came up with. Will that be cash or credit card.