19 minutes ago, killthespam said:

There is absolutely no  restriction of the minimum quantity of fuel requirement (for the 400 or -8)  for purpose of keeping hydraulic fluid cold, yes it is true the temp will rise insignificant and will pose no thereat for the operation. There is no limitation on that.

Thanks for clarifying that. It would make absolutely no sense for a modern plane with such wonderful design and so many redundant systems to be be built in such a way that just running low on fuel at some point (without even knowing WHAT exact point) would pose any kind of risk to the integrity of the plane or its ability to fly. Running out of fuel should in itself be the only issue when fuel levels are low without worrying about systems damage. Pumps that overheat and become u reliable BEFORE running out of fuel would not even be allowed in the plane by regulations. 

Edited February 10, 20197 yr by sloppysmusic

11 minutes ago, sloppysmusic said:

I'm surprised low fuel situations are not described either as they can and certainly do happen in real life. 

I'd be surprised if low fuel situations did occur in real life... I'm not referring to diversions due to low fuel but an actual case of maybe not having enough to land and taxi.  If that ever happened the pilot would be looking for a job.

It used to be fairly common in the military.  I used to watch USAF F-4 Phantoms go 'BINGO' routinely during their holds waiting their turns to land at Ramstein AB during the 70s.  But it was very rare and career ending to punch out because you flamed out.

It's really pretty basic, when the hydraulic head on the fuel pumps disappears you might get a surge and then nothing.

22 minutes ago, downscc said:

when the hydraulic head on the fuel pumps disappears you might get a surge and then nothing

Hey that's pretty useful to know. When you say nothing do you mean pump stops working completely? Won't the gravity feed still work? I'd expect if there was a worry about fuel flow there would be a warning light and checklist once the fuel got low and pump temp started rising? By happen in real life I mean when something disastrous happens like when that 777 (i think) over the ocean had to glide 100 miles to that military base on nearest island. They ran out FAST though. 

I was hoping that someone from the PMDG Support Team would jump in and respond to this?

I would like to know what fuel weight remaining after landing I should plan for with the 747-8?

Bill Clark

2 minutes ago, sbclark said:

I was hoping that someone from the PMDG Support Team would jump in and respond to this?

I would like to know what fuel weight remaining after landing I should plan for with the 747-8?

This forum is primarily user to user, so although they may or may not see the thread here, they might not necessarily respond. If you want to be sure they respond, you'll need to submit a support ticket.

1 hour ago, sloppysmusic said:

Hey that's pretty useful to know. When you say nothing do you mean pump stops working completely? Won't the gravity feed still work? I'd expect if there was a worry about fuel flow there would be a warning light and checklist once the fuel got low and pump temp started rising? By happen in real life I mean when something disastrous happens like when that 777 (i think) over the ocean had to glide 100 miles to that military base on nearest island. They ran out FAST though. 

I think you may be thinking of this situation!

https://en.wikipedia.org/wiki/Air_Transat_Flight_236

Best Regards,

Austin MacDaniels

43 minutes ago, sbclark said:

I was hoping that someone from the PMDG Support Team would jump in and respond to this?

I would like to know what fuel weight remaining after landing I should plan for with the 747-8?

Bill Clark

 

Bill,

I'm, part of tech team for PMDG (and rw pilot on 747) look at my previous post concerning fuel. There is no fixed fuel for landing, you need a fuel planning software that will figure out your requirements based on each flight and under which regulations you are part of (ICAO, FAA....), each one of them has different criteria (but pretty close). On top of that, each company has own additional rules that are different, some of them will give you a little more fuel than the minimum required by FAA or ICAO and some just plain "nothing", that's when your PIC decision comes in place. 

Actually, you need to read what are the minimum fuel requirements under ICAO , FAA .... use a flight planning software and you might be able to get to a comfortable fuel figure for landing.

In the real world, that number is a "planed" (wishful) number and always after landing you will find that number is quite different, most of the time you will have more.......

So it's impossible to "know what fuel weight remaining after landing" without a departure, arrival, load configuration, fpl, wx etc, too many unknowns.

There are some tutorials to follow and have an idea about planning and fuel, I strongly advise you to try one of them, please.

1 hour ago, sloppysmusic said:

Hey that's pretty useful to know. When you say nothing do you mean pump stops working completely? Won't the gravity feed still work?

Don't over think this Russel, there will be nothing left to flow by gravity.... well, not enough to fuel an 11 ft diameter fan jet.  Before that happens you get a FUEL QTY LOW message when amount in a tank falls below 2000 lb (see QRH) in one or more mains.  In that the average hourly burn is about 5-6000 lb this is not a message you ever want to see.

Thanks Alex,

I'm certainly glad I don't have to carry a lot of extra fuel anymore.....I read this somewhere a long time ago about keeping extra fuel for either fuel or hydraulic pump cooling.....and it just happened to be 30,000lbs!!!!!

I rely on PFPX for fuel calculations which takes into account all the requirements you mentioned.

So what is your "planned" number you shoot for?

Bill Clark

2 hours ago, nitsaw said:

I think you may be thinking of this situation!

https://en.wikipedia.org/wiki/Air_Transat_Flight_236

Best Regards,

Austin MacDaniels

I was! an interesting line:

"This caused a higher than normal fuel flow through the fuel-oil heat exchanger (FOHE), which in turn led to a drop in oil temperature and a rise in oil pressure for the #2 engine.^[5]"

Kinda relevant to this thread 😄

3 hours ago, sbclark said:

So what is your "planned" number you shoot for?

This is FAR 121 Fuel Reserves  is the minimum fuel reserve that is required for departure.     

The goal is to land with the 10 percent enroute reserve, the 30 minute holding reserve and the fuel to fly to the most distant alternate.  This is the number that I use for Reserves in the FMC.  I have noticed that the number used in the PMDG B747-8 differs from what I use, but since it is only a reminder I'm not sure if it matters.  🙂

Grace and Peace, 

5 hours ago, downscc said:

Don't over think this Russel, there will be nothing left to flow by gravity.... well, not enough to fuel an 11 ft diameter fan jet.  Before that happens you get a FUEL QTY LOW message when amount in a tank falls below 2000 lb (see QRH) in one or more mains.  In that the average hourly burn is about 5-6000 lb this is not a message you ever want to see.

Ahh been going through all the Fcoms for the 737/777 last 2 months so yes I’ve been thinking too much I know! I'm just happy to know that the fuel running out and that scary light is the ONLY thing to worry about! Having to worry about 'nearly' running out of fuel' and a plethora of subsequent system failures as well would be just too much!

To Bill the OP I could suggest this:

I too used to fret over reserve figures but once I got used to requesting performance figures on the PERF INIT page from the simulated 'company' my worries were over. They always put in a reserve amount which used to feel high to me but that's the figure I shoot for nowadays and have never been low or a large amount over since.

I think this feature only works on the 777/747, I'm sure the NGX is too ancient to utilize it too.

For the record the 777 pretty much ALWAYS gives me the figure of approx 16.5k pounds (75000kilos) in the reserve so I plan to respect this figure accordingly. I reckon following the company recommendations this way will ensure the virtual pay check keeps arriving and we therefore must be doing something right!

37 minutes ago, sloppysmusic said:

Ahh been going through all the Fcoms for the 737/777 last 2 months so yes I’ve been thinking too much I know! I'm just happy to know that the fuel running out and that scary light is the ONLY thing to worry about! Having to worry about 'nearly' running out of fuel' and a plethora of subsequent system failures as well would be just too much!

To Bill the OP I could suggest this:

I too used to fret over reserve figures but once I got used to requesting performance figures on the PERF INIT page from the simulated 'company' my worries were over. They always put in a reserve amount which used to feel high to me but that's the figure I shoot for nowadays and have never been low or a large amount over since.

I think this feature only works on the 777/747, I'm sure the NGX is too ancient to utilize it too.

For the record the 777 pretty much ALWAYS gives me the figure of approx 16.5k pounds (75000kilos) in the reserve so I plan to respect this figure accordingly. I reckon following the company recommendations this way will ensure the virtual pay check keeps arriving and we therefore must be doing something right!

It really comes down to your personal preference and how much fuel you’re comfortable landing with. What you put in the reserve amount is really just a reminder for the airplane to say hey you’re gonna burn fuel you didn’t intend to burn! I personally just put my  contingency fuel in as the amount for the reserve figure. Some may add there alternate and hold fuel onto of that which does add a little margin to be on he safe side. 

Best regards,

Austin MacDaniels

2 hours ago, Bluestar said:

This is FAR 121 Fuel Reserves  is the minimum fuel reserve that is required for departure.     

The goal is to land with the 10 percent enroute reserve, the 30 minute holding reserve and the fuel to fly to the most distant alternate.

That actually depends on the type of flight you're flying. If you're flying a flag/international flight, yes. If you're flying under US Domestic rules, it's a little difference since you wouldn't need the 10% trip time. All you would need to carry is trip fuel, fuel to the most distant alternate, and 45 minutes of holding fuel. Of course, if you're flying under EASA regulations, it's a little different.

Just now, Captain Kevin said:

If you're flying a flag/international flight, yes.

That's all I know. 🤣

Grace and Peace,