Hi.

 

I do allow for all those possibilities, please see my original post.

My question was, what if you had to use your extra fuel etc have you still got to land with a legal amount left in the tanks?

 

Hi,

 

You may use your EXTRA FUEL as that's he commanders decision to carry. You must however NOT use you Altenate fuel or Final Reserve.

 

You are required to land at your destination with your Altenate fuel and Final Reserve. If your predictions look like you will not. you either have to replan or divert. Simple as that.

Rule of thumb aim for 12-15tonnes

 

Please tell me you're referring to the 747.................

 

xD

Please tell me you're referring to the 747.................

 

xD

 

Of course..

 

Sorry I thought OP said 747...

 

My mistake..

 

For NGX = 2-3 tonnes is common

 

 

Of course..

 

Sorry I thought OP said 747...

 

My mistake..

 

For NGX = 2-3 tonnes is common

 

I thought so.

 

Thought it was a bit suss having 12t reserve in the NGX, with its 20t total cap.

 

The NGX also likes to spit out low fuel warnings with under 1t in each wing (something like that)

 

I prefer to land with about 3t reserve most times

Speaking of Alternates ... are logging of Alternates in a flight plan required by FAA? I thought I recall a FedEx cargo pilot suggesting they never plan an Alternate?

 

BTW, it appears that most Aircraft in FSX will continue running all the way until 0 ... which is probably not accurate, but there again on larger commercial AC just how accurate is the "actual" fuel quantity on board? (not what was added but actual)

Speaking of Alternates ... are logging of Alternates in a flight plan required by FAA? I thought I recall a FedEx cargo pilot suggesting they never plan an Alternate?

 

I'm not a professional pilot but I believe the following to be the case:

 

It isn't mandatory to file an alternate in your flight plan (this even means your minimum reserve can be less). But, if your plan doesn't have an alternate (sometimes the case for remote destinations), you won't be permitted to dispatch the flight unless weather at your destination is above certain minimums.

 

BTW, it appears that most Aircraft in FSX will continue running all the way until 0 ... which is probably not accurate, but there again on larger commercial AC just how accurate is the "actual" fuel quantity on board? (not what was added but actual)

 

Depends on the aircraft. A Cessna 172 just has float type sensors as you'd have in your car for example. In fact, they can be worse than those in a car as they're not damped, so even light turbulence causes the gauges to thrash around making them fairly useless. Any light aircraft pilot with any sense won't rely on them!

 

Airliners on the other hand use several (capacitive type I think) sensors, placed in multiple locations in each tank to get an accurate reading of fuel level. In addition, they have temperature sensors to provide density correction, giving the crew fuel levels in mass rather than volume. Mass provides more useful information, as 1,000kg of fuel contains the same amount of energy regardless of whether it ocupies 1m3 or 0.5m3.

 

Either way though, you're right; an aircraft engine won't keep running untill fuel is 0. The tanks will always have a certain amount of unusable fuel.

Airliners on the other hand use several (capacitive type I think) sensors, placed in multiple locations in each tank to get an accurate reading of fuel level. In addition, they have temperature sensors to provide density correction, giving the crew fuel levels in mass rather than volume. Mass provides more useful information, as 1,000kg of fuel contains the same amount of energy regardless of whether it ocupies 1m3 or 0.5m3.

Airliner fuel quantity systems are very accurate these days (though that wasn't always case in the days of analogue electronics, despite multiple sensors). However, they are designed to show usable fuel. Unusable fuel is not indicated. So zero probably means no feed to the engines.

Like some of the posters have already said, the best answer is there is no CFR requirement for a minimum fuel quantity for landing.

 

For domestic operations fuel planning, CFR 121.639 says you have to have enough fuel to accomplished the planned flight whether to the destination or furthest alternate, and after arriving have at least 45 minutes of fuel remaining (planning). However, during the actual flight, that 45 minutes of extra fuel can be used to get the airplane safely on the ground, even if the airplane lands with 10 minutes or even 1 minute of fuel remaining in the tanks, it's still legal.

 

CFR 121.639 Fuel supply: All domestic operations.

No person may dispatch or take off an airplane unless it has enough fuel—

(a) To fly to the airport to which it is dispatched;

(b)Thereafter, to fly to and land at the most distant alternate airport (where required) for the airport to which dispatched; and

©Thereafter, to fly for 45 minutes at normal cruising fuel consumption or, for certificate holders who are authorized to conduct day VFR operations in their operations specifications and who are operating non-transport category airplanes type certificated after December 31, 1964, to fly for 30 minutes at normal cruising fuel consumption for day VFR operations.

Speaking of Alternates ... are logging of Alternates in a flight plan required by FAA? I thought I recall a FedEx cargo pilot suggesting they never plan an Alternate?

 

BTW, it appears that most Aircraft in FSX will continue running all the way until 0 ... which is probably not accurate, but there again on larger commercial AC just how accurate is the "actual" fuel quantity on board? (not what was added but actual)

 

Hi,

 

Here are a page from the A320 FCOM bulletin regarding FQI accuracy. The supplier could be the same for Boeing and Airbus, Smith and BFE Goodrich(A321)

 

FAR/JAR 251337 requires that "each fuel quantity indicator is calibrated to read "zero" doing level flight when the quantity of fuel remaining in the fank is equal to the unusable fuel supply..."

 

According to Airbus the max discrepency you should see between fuel uplifted and fuel reading is plus/minus 750kgs. There are accuracy margins on the bowser, density. Also take into account the APU fuel burn.

 

Hope this helps.