The FMS manual talks about an ILS approach and autoland, but does not mention an RNAV approach. Is an RNAV approach the same procedure as an ILS approach and does autoland work the same? In other words when I choose a star and choose RNAV25L is the landing procedure the same as if I had choosen ILS25L?What is the difference between RNAV and ILS?Regards,Rod Storer

RNAV is a non precision approach, using waypoints and calculated decent profile. There is no autoland for RNAV, ILS only.

RNAV is a non precision approach, using waypoints and calculated decent profile. There is no autoland for RNAV, ILS only.

I attended an Faa seminar on gps approaches the other day.It is interesting that while a waas rnav approach gives approximately the same precision that an ils approach gives (if I recall it was about 15-30 ft. accuracy at the dh-with the waas being about 5 feet more precise than an ils) that the faa will not change the "non precision" determination for an rnav/waas approach.Having done both-I like the waas approach much more-especially when hand flying.

Yeah no doubt it is accurate, but from my studying it's still a non precision approach because it doesn't get a real time glideslope path supplied from ground equipment (and localiser). Rather the FMS has to follow a profile path that has been programmed into the nav data which relies on it's own on board nav positioning systems being accurate.I guess the FAA rather not rely so much on the accuracy of onboard navigation positioning systems of all the thousands of aircrafts approaching to make it a precision approach, or maybe they worry the airports move around. :(

I attended an Faa seminar on gps approaches the other day.It is interesting that while a waas rnav approach gives approximately the same precision that an ils approach gives (if I recall it was about 15-30 ft. accuracy at the dh-with the waas being about 5 feet more precise than an ils) that the faa will not change the "non precision" determination for an rnav/waas approach.Having done both-I like the waas approach much more-especially when hand flying.

In addition to other listed reasons, GPS coverage is not complete or gareenteed. 5ft better accuracy with waas is pretty cool, but where is the visual indicator to tell the pilot that waas is inactive and 11 out of 12 satelites are not being recieved?

Rod, just in case you are wondering: What Jay wrote in his first post is correct - and all you need to know for flying the MD-11.WAAS is GPS navigation augmented with ground stations, that enables an aircraft to descend on a glide slope similar to that provided by an ILS. The PMDG MD-11 does not have WAAS receivers on board.There are very few FS aircraft with WAAS - the Flight1 Mustang is the only one I know about that has it. Reality XP also has a a couple of WAAS-capable Garmin units that you can install in various aircraft.

Thanks for all the responses!Rod Storer

In addition to other listed reasons, GPS coverage is not complete or gareenteed. 5ft better accuracy with waas is pretty cool, but where is the visual indicator to tell the pilot that waas is inactive and 11 out of 12 satelites are not being recieved?

It is called Raim-and you do get a warning. No more of a factor imho than losing the localizer or glideslpe signal-you get a flag for that too..http://en.wikipedia.org/wiki/Receiver_Auto...rity_Monitoring

Check out the new GLS approaches at KEWR guys. This is the first of this type I've seen in the US. GLS is a GNSS/GPS-based approach (no localizer/glideslop) that is a precision approach and has minima at 200 ft just like a CAT I. I wouldn't want to fly a coupled approach below minimums in any plane, so autoland is not an issue but this topic seems to be as much about RNAV verses precision approaches and that difference is beginning to blur.

Check out the new GLS approaches at KEWR guys. This is the first of this type I've seen in the US. GLS is a GNSS/GPS-based approach (no localizer/glideslop) that is a precision approach and has minima at 200 ft just like a CAT I. I wouldn't want to fly a coupled approach below minimums in any plane, so autoland is not an issue but this topic seems to be as much about RNAV verses precision approaches and that difference is beginning to blur.

Isn't that essentially a WAAS approach?

Not according to FAA. It is indeed a different creature and it requires the entire landing environment (runway markings, lighting, obstruction clearance, etc) to be certified and TERPS. It is defined as a precision approach but a WAAS RNAV approach is a nonprecision approach.

This sounds like it could be similar to RNP (required navigation performance) approaches that are being used here in Australia at many airports? I think a US firm called Naverus is designing them for many of our airports.http://en.wikipedia.org/wiki/Required_navigation_performanceCheers,Rudy

Our RNP approaches are still considered non-precision approaches although there is vertical guidance provided. Nope, the GLS is a new breed. Very interesting.

I did the GPS RNAV 30L Z approach at KSJC which is essentially a descending 180 degree turn starting from 12000. The approach will descend and maintain the FMS speeds and then I hand flew the last portion of the approach.I used the PROF and set the altitude to 700 feet. I watched the FMS fly the speeds and do the descents. Very interesting. FSX will also activate the autotune for the ILS as you fly the approach. I found that interesting. Must be a design thing. I do not know if I did everything right but I ended up at the right place and right runway.Don L

Check out the new GLS approaches at KEWR guys. This is the first of this type I've seen in the US. GLS is a GNSS/GPS-based approach (no localizer/glideslop) that is a precision approach and has minima at 200 ft just like a CAT I.

At my field, the ILS and the LPV approach have the same minimums, and we have a plain old RNAV approach. Flying a WAAS approach is exactly the same as flying an ILS. The difference is that the LPV procedure gives a cleaner signal, so the needles don't move about as much.