Studying IFR and came across RNAV

[N1G 88]

Hi,I read a couple of articles about RNAV and understand the concepts, but who the heck today aside from commercial aviation has installed true RNAV equipment in a GA plane? Now a GPS can certainly fly the intersections but GPSis not classified from my understanding as True RNAV equipment. It seems navigation at this level is not for the meek. Anyone have any knowledge or actually used this type of equipment and if so, what type of plane was this equipment installed in?RegardsBob

[fakeflyer737 991]

RNAV is GPS and GPS is RNAV. All RNAV means is Area Navigation. Maybe your getting confused with RNP?

[scott967 62]

Take a look at this, http://www.shorelineflyingclub.com/doc/kns80.pdf which describes the KNS-80 which is a basic RNAV based on VOR/DME rho-theta. I don't think I've ever seen a KNS-80 for FS use.scott s..

[JRBarrett 3,070]

Hi,I read a couple of articles about RNAV and understand the concepts, but who the heck today aside from commercial aviation has installed true RNAV equipment in a GA plane? Now a GPS can certainly fly the intersections but GPSis not classified from my understanding as True RNAV equipment. It seems navigation at this level is not for the meek. Anyone have any knowledge or actually used this type of equipment and if so, what type of plane was this equipment installed in?RegardsBob

The KNS-80 was very popular in the 1980s and was installed in quite a variety of GA aircraft - especially those operated in commercial service - but the system has been out of production for years. I still see them from time to time, (I'm an avionics tech), but the functionality has long since been superceded by GPS. (GPS is definitely considered to be RNAV by the way).Though it is still possible to buy used KNS-80 equipment on the used market, I can't imagine why anyone would want to go to the expense of installing a KNS in an aircraft that didn't already have one, as GPS is so much easier to use, and can do many things that a rho/theta system cannot.No doubt though, that the technology was revolutionary in its day, allowing the pilot to create pseudo waypoints based on VOR/DME direction/distance coordinates, and then fly directly to them, but the process of doing that would be pretty cumbersome by modern standards.On the other hand if ever a major solar flare comes along causing major damage to the existing constellation of GPS satellites, you might find those old KNS-80 systems commanding premium prices on the used equipment market!Jim Barrett

[N1G 88]

Hi,This might be a moot point but the article does mention using a GPS but also states that the GPS must be one which is certified (may not be quite the wording used) for RNAV. I do not know if all Aircraft GPS's are certified but just curious. Reading the posts here it seems that having a radio or two that can work together to create these virtual VOR/DME intersections are not used. They also mentioned inertia navigation. Not sure how outdated this article was but understanding inertia nav was a little overwhelming. So do commercial airlines still use inertia nav? I am just beginning to learn about IFR and I must say I now have an enormous amount of respect for these pilots who have gone through the pain (and money) to become IFR certified. There is soooo much to learn. The charts alone is information overload. I guess like anything if you do it enough it becomes second nature. RegardsBob

[NewChucky 0]

I'll be repeating some of what other people have said already, but maybe this will help. RNAV means 'area navigation', and is any navigation system that can navigate to an arbitrary point in space, rather than to/from ground-based navigational aids. GPS is one example of such a system - LORAN was another. Many early RNAV systems used inertial reference systems, usually with some form of positional cross-checking. Those of us who use the Level-D 767 are familiar with that kind of system. I believe the cross-checking is DME-DME. The answer to whether airliners use inertial reference or GPS is 'it depends'. Most airliners being built today (well, all, as far as I know) do use GPS as their primary nav source. Some of the earlier glass cockpit planes do not (757s and 767s, for instance). Some airliners don't have RNAV capability at all. This weekend I'll be on a Dash-8 that just has VORs and a DME.As for which aircraft GPSs are RNAV devices: any GPS which is certified for use as an IFR GPS is by definition an RNAV device. Certification requirements are laid out in various Technical Standards Orders or TSOs. Hand-held GPSs - even when mounted in the aircraft panel somehow - are never certified for use. The Garmin G4xx and G5xx units are certified, as is the device in the G1000. There are a number of certified GPSs from King as well - the KLN94 is the most well known, I believe. There are plenty of others for larger aircraft, and presumably more for light planes as well. The point is, though, many many GA aircraft are RNAV equipped.

[N1G 88]

Hi,Thanks for taking the time I do appreciate it. One more question if you have time. It would seem to me that trying to hand fly a complicated Sid or Star would be almost impossible, at least when some turns would require a higher level of accuracy. Is this true or do some pilots actually hand fly these?Bob

I'll be repeating some of what other people have said already, but maybe this will help. RNAV means 'area navigation', and is any navigation system that can navigate to an arbitrary point in space, rather than to/from ground-based navigational aids. GPS is one example of such a system - LORAN was another. Many early RNAV systems used inertial reference systems, usually with some form of positional cross-checking. Those of us who use the Level-D 767 are familiar with that kind of system. I believe the cross-checking is DME-DME. The answer to whether airliners use inertial reference or GPS is 'it depends'. Most airliners being built today (well, all, as far as I know) do use GPS as their primary nav source. Some of the earlier glass cockpit planes do not (757s and 767s, for instance). Some airliners don't have RNAV capability at all. This weekend I'll be on a Dash-8 that just has VORs and a DME.As for which aircraft GPSs are RNAV devices: any GPS which is certified for use as an IFR GPS is by definition an RNAV device. Certification requirements are laid out in various Technical Standards Orders or TSOs. Hand-held GPSs - even when mounted in the aircraft panel somehow - are never certified for use. The Garmin G4xx and G5xx units are certified, as is the device in the G1000. There are a number of certified GPSs from King as well - the KLN94 is the most well known, I believe. There are plenty of others for larger aircraft, and presumably more for light planes as well. The point is, though, many many GA aircraft are RNAV equipped.

[NewChucky 0]

Hi,Thanks for taking the time I do appreciate it. One more question if you have time. It would seem to me that trying to hand fly a complicated Sid or Star would be almost impossible, at least when some turns would require a higher level of accuracy. Is this true or do some pilots actually hand fly these?Bob

I'm just a private pilot, and I don't yet have my instrument rating (I'm working on it, which is why these things are fresh in my mind) so I can't comment with any authority on what the folks in the big aluminum tubes do. Most SIDs and ODPs (Obstacle Departure Procedures) are relatively simple to fly. They certainly can be flown by hand since many of us don't fly aircraft with roll steering autopilots. RNAV SIDs, which are becoming more common (KBOS just got a bunch, for example) are a little bit more complex. There are two types: A and B. Type B departures are more restrictive and "require the use of CDI/flight directors or autopilot" (I'm quoting from the Instrument Procedures Manual, page 2-28 here). I'm not sure if the requirement is CDI and flight director, or CDI or flight director. The answer to your question, though, is that it must in principle be possible to fly these procedures by hand, with the help of a flight director. As to what flight crews actually do, I can't say.

[JohnFromCO 15]

Hi,Thanks for taking the time I do appreciate it. One more question if you have time. It would seem to me that trying to hand fly a complicated Sid or Star would be almost impossible, at least when some turns would require a higher level of accuracy. Is this true or do some pilots actually hand fly these?Bob

Sid's, now known as Departure Procedures (DP), and STAR's are designed to be flown by hand. Autopilots are not standard equipment on every aircraft flying DP/STAR's so they are designed accordingly. They might look complex but in reality they are designed to simplify flow into approaches and out of terminal area's. Even harder DP's found up here in the mountains (KEGE - Gypsum four) are pretty easy to fly once you review them. If you really don't want a DP or STAR you could always file "NO DP / STAR" in the notes on your IFR flight plan. ATC really loves when you do that. We file that way occasionally to avoid unnecessary routing out of smaller satellite airports. However, it can also blow up in your face as you get stuck waiting for release into the system. John

[N1G 88]

John,I am still a little confused. If as stated previously, the GPS can be used for Area Navigation which would I assumed would include DP's and Star's. If flying a complex arrival with multiple turns and the turns I am assuming are just virtual intersections also. So if turns are virtual paths that would only leave the gps to rely on for a hand flown procedure. This would seem difficult if not impossible to follow the drawn procedure on the gps since the gps can be a very small screen and trying to follow the path would seem extremely difficult. Maybe I am missing something here and the procedure turns are done another way. If the GPS is not used and you are hand flying, then how is this done?RegardsBob

Sid's, now known as Departure Procedures (DP), and STAR's are designed to be flown by hand. Autopilots are not standard equipment on every aircraft flying DP/STAR's so they are designed accordingly. They might look complex but in reality they are designed to simplify flow into approaches and out of terminal area's. Even harder DP's found up here in the mountains (KEGE - Gypsum four) are pretty easy to fly once you review them. If you really don't want a DP or STAR you could always file "NO DP / STAR" in the notes on your IFR flight plan. ATC really loves when you do that. We file that way occasionally to avoid unnecessary routing out of smaller satellite airports. However, it can also blow up in your face as you get stuck waiting for release into the system. John

[JohnFromCO 15]

John,I am still a little confused. If as stated previously, the GPS can be used for Area Navigation which would I assumed would include DP's and Star's. If flying a complex arrival with multiple turns and the turns I am assuming are just virtual intersections also. So if turns are virtual paths that would only leave the gps to rely on for a hand flown procedure. This would seem difficult if not impossible to follow the drawn procedure on the gps since the gps can be a very small screen and trying to follow the path would seem extremely difficult. Maybe I am missing something here and the procedure turns are done another way. If the GPS is not used and you are hand flying, then how is this done?RegardsBob

DP's and STAR's use radials and intersections based on NavAids. Before the GPS you would fly x radial off a VOR to a intersection/VOR then fly another radial to another intersection/VOR until you are enroute or on the approach. For instance look at the Rockies Seven departure Red Table (DBL) Transition (copy here). If you depart KDEN you would follow the 251 radial off the DEN VOR to the Connor intersection. Connor is 47 DME from the DEN VOR. So you would set your CDI to 251 and intercept the course then keep it centered. Once your DME reaches 47 nm you would then intercept the 062 course (about a 242 heading) inbound to the DBL VOR. Keep the CDI centered and you are golden. Since you are just learning it seems difficult but it really isn't once you fly them. You should be able to fly the DP/STAR without a GPS as generations have before. You simply navigate by following the plate/chart in your head. Same with using high alt and low enroute charts. John

[brucek 38]

John,I am still a little confused. If as stated previously, the GPS can be used for Area Navigation which would I assumed would include DP's and Star's. If flying a complex arrival with multiple turns and the turns I am assuming are just virtual intersections also. So if turns are virtual paths that would only leave the gps to rely on for a hand flown procedure. This would seem difficult if not impossible to follow the drawn procedure on the gps since the gps can be a very small screen and trying to follow the path would seem extremely difficult. Maybe I am missing something here and the procedure turns are done another way. If the GPS is not used and you are hand flying, then how is this done?RegardsBob

Hi Bob,Firstly, to get an instrument rating, you have to be able to hand fly any procedure, other than some approaches that require an autopilot for close to (or at) 0/0 minimums. I'm not sure which procedures you are talking about that you think would be difficult to hand fly, that also rely on GPS (or some other form of R-NAV). Do you have an example of one? You also mentioned "procedure turns", is that the issue? PT's are an integral part of an approach that are sometimes used to get you aligned with the inbound course, although I have never flown one that I would call "difficult". Can you give us an example of what you are asking about?Also- just as the autopilot controls the aircraft from GPS or other navigation sources, the pilot can use some of this logic to also fly the aircraft manually. It's known as a "flight director", and gives visually to the pilot the same cues as the AP gets electronically.Thanks, Bruce.

[N1G 88]

Hi,I really have no specific approach I was thinking of really , just thinking out loud. Yes the flight director! I forgot all about that little bugger. Never used it much with VFR. I can see how that may be a benefit to use this. Let me try out the flight director and see what I can do. It just seemed funny to be staring at the GPS and hand flying a complicated Star. The flight director does make sense though. Again, I never used it but now that you mention it using the FD would seem to be a very helpful tool. Thanks!!Bob

[brucek 38]

Hi,I really have no specific approach I was thinking of really , just thinking out loud. Yes the flight director! I forgot all about that little bugger. Never used it much with VFR. I can see how that may be a benefit to use this. Let me try out the flight director and see what I can do. It just seemed funny to be staring at the GPS and hand flying a complicated Star. The flight director does make sense though. Again, I never used it but now that you mention it using the FD would seem to be a very helpful tool. Thanks!!Bob

Hi Bob,Also, if your navigating with a GPS, to some extent the FD is unnecessary as you will get a "turn anticipation" from the GPS display, and a text that tells you when to commence the turns (at least with the GNS series devices). I'm not sure what the default GPS in FSX gives you for turn anticipation, however if you really want to explore GPS flight in FSX I would highly recommend the Reality XP products as an add-on. Note that I am not involved in any way with RXP. And when the GPS tells you to turn, it is assuming (as we all do in IFR flight) that the turn will be at a standard rate (unless you are on short final on the LOC).Continue to post any questions that you might have. I am currently building a new PC at home so do not have an instance of FSX to try any specific examples that you may have, however if you are referencing published charts / approaches then we don't actually need FSX running to help you (unless the issue is FSX specific). Bruce.

[N1G 88]

Hi Bruce,Appreciate the offer and thanks. Well I do have the RXP 500W and remember trying to understand it. Its been over a year and now getting back into FSX. I have started reading the training manual and I must admit that I am having issues understanding all the options. I will do more reading tonight but so far it looks like I need a 40 hour class LOL! For an old VFR pilot I must say that this is really a challenge.Thanks Bruce!!Bob

Hi Bob,Also, if your navigating with a GPS, to some extent the FD is unnecessary as you will get a "turn anticipation" from the GPS display, and a text that tells you when to commence the turns (at least with the GNS series devices). I'm not sure what the default GPS in FSX gives you for turn anticipation, however if you really want to explore GPS flight in FSX I would highly recommend the Reality XP products as an add-on. Note that I am not involved in any way with RXP. And when the GPS tells you to turn, it is assuming (as we all do in IFR flight) that the turn will be at a standard rate (unless you are on short final on the LOC).Continue to post any questions that you might have. I am currently building a new PC at home so do not have an instance of FSX to try any specific examples that you may have, however if you are referencing published charts / approaches then we don't actually need FSX running to help you (unless the issue is FSX specific). Bruce.