747-400 Flight Management Computer

[Guest IRE]

Hi,I pretty sure that I stuffed up in posting the topic I require information for, so seconds out, round 2.Looking on Page 51, to the bottom right hand side of that page, ACT DES FORECASTS window there is a line that shows, TAI/ON ALT with a blank line below that next to the line select 1 input button.Can anyone tell me if this is a 'dud' or opperating input to help with the 747's decent profile.If it is, where can I look to obtain the relevent information to load into that part of the FMC.I've read the 747-400's FMC users guide and can't seem to locate anything. Or maybe I've just missed seeing it as 60 pages is a long read!Any assistance would be appreciated.Regards, Ian ELLIS. N.S.W. Australia.

[FLEX1978 373]

Hi,I pretty sure that I stuffed up in posting the topic I require information for, so seconds out, round 2.Looking on Page 51, to the bottom right hand side of that page, ACT DES FORECASTS window there is a line that shows, TAI/ON ALT with a blank line below that next to the line select 1 input button.Can anyone tell me if this is a 'dud' or opperating input to help with the 747's decent profile.If it is, where can I look to obtain the relevent information to load into that part of the FMC.I've read the 747-400's FMC users guide and can't seem to locate anything. Or maybe I've just missed seeing it as 60 pages is a long read!Any assistance would be appreciated.Regards, Ian ELLIS. N.S.W. Australia.

Hi Ian, as far as I'm aware it's not a dud. The information you require will come from your ATIS, Company ACARS or your dispatcher would give you expected arrival info. As a general rule if I know I will be expecting to encounter icing conditions 10c or lower at the field I will aim to have wing and engine AI on by 18000ft at least unless I'm in dense clouds earlierRob

[Spidierox 4]

I think this is a setting to turn on Anti ice at a certain altitude.You can test it by :1) entering an altitude.2) do a flight and see if EICAS shows TAI indicating anti-ice activated.Dieter

[FLEX1978 373]

I think this is a setting to turn on Anti ice at a certain altitude.You can test it by :1) entering an altitude.2) do a flight and see if EICAS shows TAI indicating anti-ice activated.Dieter

It doesn't turn anti ice on, It's used to calculate VNAV path during descent, this is due to an increase in Idle N1/EPR Anti Ice requires a slightly higher Idle thrust in descent, the bleed air from the engines is what provides AIYou can notice it more on the ground, have a look at your N1/EPR reading then turn NAI on and you will see the increase.Rob

[Airbrakes 0]

Hi Ian, as far as I'm aware it's not a dud. The information you require will come from your ATIS, Company ACARS or your dispatcher would give you expected arrival info. As a general rule if I know I will be expecting to encounter icing conditions 10c or lower at the field I will aim to have wing and engine AI on by 18000ft at least unless I'm in dense clouds earlierRob

NAI should be turned on before the TOD if you're expecting icing conditions regardless of what the SAT is.

[FLEX1978 373]

NAI should be turned on before the TOD if you're expecting icing conditions regardless of what the SAT is.

According to who's SOP? seems like a lot of extra fuel burn, but hey each company does it there own way.Rob

[tcas_climb 45]

According to who's SOP? seems like a lot of extra fuel burn, but hey each company does it there own way.Rob

Just squeezing in 2 cents here.I think that was a temporary solution mostly for RR RB211 engines that had some kind of problem when descending from high altitude at idle with low EPR setting. It was possibly an icing issue even with no visible moisture i dont remember.

[Airbrakes 0]

According to who's SOP? seems like a lot of extra fuel burn, but hey each company does it there own way.Rob

That's in the AOM.

[FLEX1978 373]

That's in the AOM.

I use the Singapore airlines FCOM and they use P&W is this in the PMDG AOM? could you point me in the right direction, I've read the thing way to many times lol but don't remember seeing that.CheersRob

[Airbrakes 0]

I use the Singapore airlines FCOM and they use P&W is this in the PMDG AOM? could you point me in the right direction, I've read the thing way to many times lol but don't remember seeing that.CheersRob

Yeah, it's in section 04 - Limitations page 8

[FLEX1978 373]

Thanks for that, I did a little searching on the web and it seems this has been discussed a lot on certain pilot forums, seems there are airlines and crew that state you should only use it when entering icing conditions, thinking about it personaly I have to say I agree with using it before T.O.D better safe then sorry.here's a post I found.Gentlemen,It's important to remember that the engine anti-ice system is just that...anti-ice. Allowing ice to build up could easily cause severe engine damage, flame out, etc. This is why it's important to have the engine anti-ice system ON prior to entering icing conditions.It does not hurt anything to have the engine anti-ice system ON (if you're anticipating icing conditions), and then discover it really wasn't needed. Yes, you're burning a bit more fuel. But, the other side of the coin is: How much money do you save over the lifetime of your career by damaging an engine? You can buy a lot of fuel for the cost of such an occurrence.We've beaten this topic to death many times, here, in ***** My advice is to follow your company's SOP. It protects you, and, in this regard, it will protect your engines. I've flown with many guys over the years who have their own 'techniques'. Not a good idea. And, some guys will pretend that, with having their own 'techniques', they employ some degree of piloting proficiency that others lack. WRONG!!!!!Follow the SOP. My philosophy...when in doubt (about the possibility of icing) turn on the engine anti-ice. (This covers the 'anticipated' clause of the SOP.)Another interesting note...some erroneously believe that, under certain atmospheric conditions, turning on engine anti-ice could actually increase the likelyhood of engine flameout and/or damage due to icing. WRONG!!!!!If this were true, there would be SOPs/limitations regarding this.When in doubt, use it. The worst-case down-side...you've wasted a bit of fuel.Fly safe,

[Airbrakes 0]

Yeah, this topic has been beat to death on many forums (both FS and R/W aviation forums). I personally think it's better for the engine and the VNAV FPA to select NAI before the TOD. From what I read on another forum, NAI is a preventative tool and WAI is a reactive tool.

[FLEX1978 373]

Yeah, this topic has been beat to death on many forums (both FS and R/W aviation forums). I personally think it's better for the engine and the VNAV FPA to select NAI before the TOD. From what I read on another forum, NAI is a preventative tool and WAI is a reactive tool.

Hey I missed your sig, just realised you fly for Globe VA. I have to say without a doubt the best VA out there when it comes to realism. I flew the Atlas/Polar 744 freighters with you guys for a while it was a great experience.CheersRob

[Airbrakes 0]

Hey I missed your sig, just realised you fly for Globe VA. I have to say without a doubt the best VA out there when it comes to realism. I flew the Atlas/Polar 744 freighters with you guys for a while it was a great experience.CheersRob

I agree with that in so many ways.... Do you still fly with us?

[FLEX1978 373]

I agree with that in so many ways.... Do you still fly with us?

No I've moved to the MD11, only have limited time to fly so prefer to stick to one aircraft at a time. But if I go back to the 744 or move to the LDS767 will look you guys up.Cheers Rob