Ryan or someone from PMDG - could you confirm you've modelled the RNP/ANP to come on the PFD once the Flight Director(s) are turned on please. I know the NGX they only show on the PFD once LNAV & VNAV are active - so was curious as to which way it's modelled this time around. I'm assuming that's how it is in the real NG!

 

Cheers,

Luke

@Tabs ?

Works exactly how the manuals say it does:
 

"NPS display when LNAV, VNAV or TOGA are active modes or when LNAV is armed. Additionally, the scales will remain in view and operate even if other roll or pitch modes are selected while the airplane remains within RNP containment of the magenta path. Vertical scales do not display during cruise with VNAV PTH active."

The NG and 777 are not the same airplane, there's a million differences.

I know, just checking! Thank you.

Can someone tell me what the RNP/ANP thing does pls? what is,the little purple diamond for and what position should it be in? what are the numbers at either end for? Thank you.

 

 

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Hi,

 

I'm far from a specialist but afaik:

RNP = Required Navigation(al) Precision (lateral margins on a track)

ANP = Actual Navigation(al) Precision, your actual nav accuracy.

 

Depending on the area and the tracks, the RNP differs (airways, SID/STARS...). RNP may be RNP1 for approach for exemple up to RNP10 for oceanic zones where low accuracy is required on tracks.

If I'm not wrong, RNP1 corresponds to 1nm accuracy, but some may confirm that.

It's not just lateral - there's vertical RNP/ANP too. (shown next to the altitude tape and on the path deviation indicator on the ND)

 

RNP is the amount of aircraft position precision required to fly a particular procedure. (FMC position comes from a bunch of sources - GPS, the ADIRUs, ground-based navaid raw data etc) ANP is the theoretical maximum precision the aircraft currently has given the current state of those sources. It's *not* the actual position of the airplane or anything like that - if the plane knew its actual position at all times there'd be no need for this system in the first place. All it can ever know is that the aircraft's position is within some margin of error. If that margin is less than RNP, everything's fine and you can fly the procedure. If it's outside of it, you climb to the MSA for the procedure and troubleshoot (a go-around/missed approach basically).

It's not just lateral - there's vertical RNP/ANP too. (shown next to the altitude tape and on the path deviation indicator on the ND)

 

RNP is the amount of aircraft position precision required to fly a particular procedure. (FMC position comes from a bunch of sources - GPS, the ADIRUs, ground-based navaid raw data etc) ANP is the theoretical maximum precision the aircraft currently has given the current state of those sources. It's *not* the actual position of the airplane or anything like that - if the plane knew its actual position at all times there'd be no need for this system in the first place. All it can ever know is that the aircraft's position is within some margin of error. If that margin is less than RNP, everything's fine and you can fly the procedure. If it's outside of it, you climb to the MSA for the procedure and troubleshoot (a go-around/missed approach basically).

ADIRU... a curious invention

Huh?  Air Data Inertial Reference Unit - why is that a curious invention?

 

 

I'm far from a specialist but afaik:
RNP = Required Navigation(al) Precision (lateral margins on a track)
ANP = Actual Navigation(al) Precision, your actual nav accuracy.

 

Just to be pedantic - the P in RNP and ANP is actually "performance" not "precision".  Different levels of RNP can be certified, usually RNP10 or RNP4, meaning that the aircraft must be able to define its position, to a 95% confidence level, within a radius of either 10 or 4 nautical miles radius respectively. These 95% confidence levels provide 99.999% confidence level containment limits for suitably equipped aircraft of 20nm and 8nm respectively, allowing approval of reduced separation standards. There's lots of good stuff on the FAA and ICAO websites for those interested in the details.

 

Cheers

@Tabs

I was flying some retros the other day and I was just admiring how far we've gone since using stars and intuition to fly  :rolleyes: