Some Questions regarding Charts and procedures

[scandinavian13 5,192]

 

 

i desided to go for a RNAV17L in KDEN Denver.

 

A reasonable choice (and the choice of the future), but again, I'll stress that you shouldn't expect similar if you fly RW or on VATSIM.  ILS reigns supreme...for now.

 

 

 

Only Q remain is the 2 different RNAV Procedures. RNAV GPS and RNAV (RNP) for KDEN 17L. Both Procedures makes use of LNAV/VNAV.
 
I thought the RNAV"GPS"  procedures was for smaller planes without LNAV/VNAV.?

 

RNAV(GPS) and RNAV(RNP) isn't a matter of "do they use LNAV/VNAV?"  It's a matter of "can they maintain the RNP for the approach?"  RNAV(GPS) isn't about aircraft size, or use of LNAV/VNAV.  It's that it isn't an RNP approach, and that it specifically uses GPS as a method of RNAV.

 

For what it's worth, some of United's 757s can't do most of the RNAV approaches out there because they don't have GPS (at all - they're DME/DME/IRU - but since the chart says "RNAV(GPS)" it requires GPS).  Meanwhile, corporate jets (as Dan mentioned earlier) have been doing this for quite some time.  Don't fall into the aircraft size trap that everyone seemingly falls into.

 

Remember:

RNAV is "aRea NAV."  It's simply a concept where a plane can go from one point in space, directly to another (doesn't rely on VOR radials and so on).  GPS is a method of RNAV.  Inertial Reference is also a type of RNAV.  GPS and INS are concepts of the larger concept called RNAV, just like turbojets and props are concepts of the larger concept called airplanes.

[Michael Moe 495]

A reasonable choice (and the choice of the future), but again, I'll stress that you shouldn't expect similar if you fly RW or on VATSIM.  ILS reigns supreme...for now.

 

 

 

 

RNAV(GPS) and RNAV(RNP) isn't a matter of "do they use LNAV/VNAV?"  It's a matter of "can they maintain the RNP for the approach?"  RNAV(GPS) isn't about aircraft size, or use of LNAV/VNAV.  It's that it isn't an RNP approach, and that it specifically uses GPS as a method of RNAV.

 

For what it's worth, some of United's 757s can't do most of the RNAV approaches out there because they don't have GPS (at all - they're DME/DME/IRU - but since the chart says "RNAV(GPS)" it requires GPS).  Meanwhile, corporate jets (as Dan mentioned earlier) have been doing this for quite some time.  Don't fall into the aircraft size trap that everyone seemingly falls into.

 

Remember:

RNAV is "aRea NAV."  It's simply a concept where a plane can go from one point in space, directly to another (doesn't rely on VOR radials and so on).  GPS is a method of RNAV.  Inertial Reference is also a type of RNAV.  GPS and INS are concepts of the larger concept called RNAV, just like turbojets and props are concepts of the larger concept called airplanes.

 

 

Thanks alot Kyle :-)

 

Again from Denmark and using Navigraph Charts they do have RNP and LNAV/VNAV DH(A) on there RNAV(GPS) Charts.

 

That why i get confused i think :-)

 

Michael

[downscc 1,327]

Michael, I'm not familiar with Denmark charts but I am guessing that you are referring to different minima for LNAV/VNAV and LNAV only? My panel has a Garmin 530 that provides for LNAV only RNAP(GPS) approaches but high-end (i.e., pricey) systems will provide vertical (VNAV) clearance as well, which logically allows the procedure designers to assign a lower DH or minima. RNP is actually a very different philosophy from RNAV(GPS) in that in RNP there are requirements for crew training and the equipment must provide additional information to the pilot regarding actual navigation performance and deviations and the equipment generally includes VOR/DME/IRS and GPS input; but RNAV(GPS) is just GPS and without WAAS can have an acceptable errors in excess of 100 m (I forget the actual CEP but it's greater than that).

[scandinavian13 5,192]

 

 

high-end (i.e., pricey) systems will provide vertical (VNAV) clearance as well, which logically allows the procedure designers to assign a lower DH or minima.

 

...but they're nice, aren't they?  There was some CPA around here who had a Malibu that I got to toy with occasionally.  He always had the latest and greatest.

 

I used to be very skeptical of getting rid of ground-based navaids in favor of GPS, but after WAAS and other GBASS implementations, I'm pretty much sold.  Add RNP into that, and I'm ready to convert...at least theoretically. ha ha.

[Budbud 227]

Regarding GPS with SBAS and GBAS, we use them extensively in my job on offshore construction vessels for precised positioning (I'm merchant seaman), calling them generically DGPS (Differential GPS) and despite the fact they can provide positions as precised as 10cm, they are quite sensitive to atmospheric perturbations (especially scintillation due to sunspot).

It leads to erratic positions and even complete loss of signal in some areas of the globe and some periods of the day.

 

I guess the systems used in airplane are also sensitive to the same perturbations? Or are there magic bullets?

Otherwise, I'm not ready to give 100% trust to these systems yet, not without ground-based backup aids.

[Michael Moe 495]

Michael, I'm not familiar with Denmark charts but I am guessing that you are referring to different minima for LNAV/VNAV and LNAV only? My panel has a Garmin 530 that provides for LNAV only RNAP(GPS) approaches but high-end (i.e., pricey) systems will provide vertical (VNAV) clearance as well, which logically allows the procedure designers to assign a lower DH or minima. RNP is actually a very different philosophy from RNAV(GPS).

 

 

 

 

 

 

Hi,

 

Yep i am refering to Minima LNAV/VNAV on the GPS Charts in which RNP also is mention.

 

Thanks

 

Michael

[Jetblst 23]

I'll add a little more fun to this.  Even though there are VNAV minima on the charts, not too many operators have the authorization to use VNAV anyway.  We have to use LNAV only as that is all our Operations Specifications allow at this time. Most VNAV minima will bring you down 250 feet AGL.  ILS (Radio Based) will bring you down most often to 200 feet agl.  So it's very true, the ILS is assigned most often in lower weather.  Most of the time you will get the approach lights and when you do, most Ops Specs will allow you to then decend down to 100 feet ABOVE the touchdown point, allowing us to then get in when weather is REALLY crummy.  200 ' and 1\2 mile vis.  Most airlines (FAR PART 121 operators) have the same abilities, so for FSX purposes it might add some realisim to remember the decend to 100 feet above the Touch Down Point rule when you get the approach lights.  Makes for some really great flights.

[Michael Moe 495]

Thanks,

 

All though all this is basic stuff for all of you i am glad you take your time to answer these questions as i do find it a little hard to just Google all this  :rolleyes: and lead it to real life meaning full information

 

Thanks again 

 

Michael

[downscc 1,327]

 

 

I guess the systems used in airplane are also sensitive to the same perturbations? Or are there magic bullets?
Otherwise, I'm not ready to give 100% trust to these systems yet, not without ground-based backup aids.

 

In a nutshell, yes. The most basic of TSO's GPS devices have multiple channels and pertubation sensing as well as NOTAMs issued to warn of solar activity forecasts. I would not want to go back to VOR/LORAN only navigation, and I am really spoiled by adding a XM receiver to download current METARs and NEXRAD from NWS that appears right on the map display. We also use GPS systems for surveying at the engineering company I recently retired from, which is a real money saver because all the data is electronically stored and when brought in from the field and put in an engineering workstation the productivity and quality is significantly increased. Now days, this is a tool that you either use or you lose the business to someone else that has it.

[Budbud 227]

For sure, we can't get rid off GPS systems. Only they need in some case to be backed up, in our case with other position references as HPR (hydroacoustic) or laser beam system. 

DPGS with different types of corrections may react differently to the perturbations but in particularly sensitive areas like in Gulf of Guinea, I have seen all the vessels losing all the GPS signals at the same time whatever equipment they have.

 

 

In the case of landing system, the only system to my knowledge which allows autoland is ILS for the moment.

I don't when the GPS will be reliable and precised enough to completely replace ILS?

[downscc 1,327]

 

 

In the case of landing system, the only system to my knowledge which allows autoland is ILS for the moment.
I don't when the GPS will be reliable and precised enough to completely replace ILS?

 

Point taken; however, assume autoland is generally used only for CAT II-III then this is a moot point (many operators want their crews to fly the airplane). GLS approaches mimic CAT I ILS minima already and given the exorbant cost of maintaining thousands of ground radio stations (equipment and manpower), it's not unreasonable to expect GLS CAT II within the next 10 years (or 20 given the slow pace of government and industry investment).

[Budbud 227]

 

 

it's not unreasonable to expect GLS CAT II within the next 10 years (or 20 given the slow pace of government and industry investment).

 

Something I among others expect for flight sim to get rid of the problems of outdated sceneries with wrong frequencies and bearings! 

(That point is already discussed in some other topics so it is just a joke ^_^ )