@Kyle: because it is a non-precision approach, and what is wrong with FPA vertical mode? IAN also assumes 3.0 degrees, which I'm not sure can be altered. Try flying one of the NDB or VOR approaches into Innsbruck.

 

IAN is basically a modern version of these older types of approaches.  They offered IAN instead of good old VOR tracking because IAN takes good old VOR tracking and makes it a heck of a lot easier.  The point of IAN is to make NPAs as easy as ILSs to fly.

 

It does not assume 3.0 degrees.  It calculates a vertical profile that satisfies the altitude constraints (attempting to make it constant, from what I understand, in order to make it more ILS-like).  The problem at LOWI is that the descent angle is 8% (and then 11% for the special)...and that it's being flown in a 777, which no one in their right mind would ever try.

 

FPA vertical mode does not guarantee that altitude restrictions would be met, and using that would essentially be like going back to the old way of NPAs because the whole point of IAN is to add vertical guidance.

 

Having read your posts over the past few years I can see that you're both passionate and opinionated, much like myself.  You have to temper that passion by being able to step back and look at the information that's right in front of you (and taking the time to fact check when at all possible), though.  Otherwise you miss what's been sitting in front of you the whole time: IAN is "VOR/NDB approaches version 2."

Sorry guys,

could somebody explain IAN to me?

 

Yes, we are speaking about the T7 and not the 737.

 

Thanks,

Christos

 

 

I just checked - I'm confusing it with another aircraft. No IAN mentioned in the 777 options.

 

Still... inability to track an actual VOR radial is annoying, and doesn't make much sense.

 

@Christos: IAN is short for Integrated Approach Navigation. As Kyle explained above, it is used for non-precision approaches, and condenses the approach (both lateral and vertical profile) into an ILS-style display. It is NOT a suitable replacement on its own, and still requires that you monitor the raw data.

 

@Kyle: thanks for the clarification on the vertical flight path.

 

Best regards,

Robin.

 

 

Still... inability to track an actual VOR radial is annoying, and doesn't make much sense.

 

Think about it, though.  When would you ever be bringing a 777 into an airport where you'd actually need something like that?

Still... inability to track an actual VOR radial is annoying, and doesn't make much sense.

 

Because it's not really necessary. VOR (and ILS for that matter) isn't the super steady interference free wonder device that FSX depicts it to be. The ANP of a modern FMS equipped aircraft is generally superior to what you can expect to receive from a VOR; hence fly LNAV/VNAV while monitoring raw data.

 

In fact, I expect the only reason you'd fly a VOR approach in a 777 these days, instead of an RNAV approach, is because an RNAV approach isn't (yet) available for that runway.

 

 

The ANP of a modern FMS equipped aircraft is generally superior to what you can expect to receive from a VOR; hence fly LNAV/VNAV while monitoring raw data.

 

Yup.  If you can find them, there used to be a few UAX routes flown by Colgan and one other carrier.  Colgan's 340s at the time were /A while the other carrier was /G.  The difference in the precision was very noticeable by looking at the FlightAware tracks.

Well I think that is why they call them NON-PRECISION approaches.

 

ILS is good enough for autoland, but RNAV is NOT.

 

I am aware of the real-world performance of these nav systems vs. the sim, but in the end, the beacons were checked out for the approaches they are used with, and so conform to the accuracy requirements for the class of approach. Whilst an FMS system may generally be able to fly the same path more accurately nay consistently, the whole premise of the usage of ground based stations is missed; that is they are fixed, ground-based stations external to the aircraft using them. Even the Shuttle used MLS on final despite the billions poured into its nav systems.

 

 

Check out the position error!! If the Shuttle's inertial nav systems were not good enough...

 

Best regards,

Robin.

They're called non precision because they don't have vertical guidance, that's it.

 

And VOR approaches aren't retained because they offer the benefit of being ground based, they're retained because there are many aircraft still flying without RNav equipment certified for RNav approaches (orRNavRNav approach hasn't been developed for that runway yet).

 

Certainly a VOR approach offers no advantage to a modern airliner save the redundancy if ANP of the FMC degrades and that's the only approach left.

 

 

They're called non precision because they don't have vertical guidance, that's it.

 

The might have. IGS at Kai Tak or LOC/DME in Innsbruck have vertical guidance, even though they are non-precision.

 

They are non-precision because they will not align you to land precisely like an ILS would do.

 

 

 

The problem at LOWI is that the descent angle is 8% (and then 11% for the special)...and that it's being flown in a 777, which no one in their right mind would ever try.

 

I don't see why not.

 

 

 

Sorry guys,
could somebody explain IAN to me?

 

As it has been said, basically it takes any approach in the airplane database (or a created visual), and makes it look like an ILS for you. You can use it while monitoring raw data (in case of VOR or NDB approaches, unless certified otherwise), or while not even monitoring, if certified so.

 

 

Whilst an FMS system may generally be able to fly the same path more accurately nay consistently, the whole premise of the usage of ground based stations is missed; that is they are fixed, ground-based stations external to the aircraft using them.

 

That's what RNP is for - self-checking performance monitoring in airplane nav systems, able to ascertain own position AND the precision of said position basing several independent datapoints (usually GNSS, IRS, DME/DME scan in modern airliners). Plus it will alert you as soon as it figures out it is unable to keep the required precision for whatever reason (say, if the GPS signal is erratic and one of the DME radios is out)

We had a similar discussion here:

 

http://forum.avsim.net/topic/422488-intercepting-vor-radial-when-in-hdg-mode/

 

Read that and things should be pretty clear.

 

If not, feel free to ask again ofcourse.

The might have. IGS at Kai Tak or LOC/DME in Innsbruck have vertical guidance, even though they are non-precision.

 

They are non-precision because they will not align you to land precisely like an ILS would do.

 

 

 

I don't see why not.

 

 

 

As it has been said, basically it takes any approach in the airplane database (or a created visual), and makes it look like an ILS for you. You can use it while monitoring raw data (in case of VOR or NDB approaches, unless certified otherwise), or while not even monitoring, if certified so.

 

 

 

That's what RNP is for - self-checking performance monitoring in airplane nav systems, able to ascertain own position AND the precision of said position basing several independent datapoints (usually GNSS, IRS, DME/DME scan in modern airliners). Plus it will alert you as soon as it figures out it is unable to keep the required precision for whatever reason (say, if the GPS signal is erratic and one of the DME radios is out)

Non Precision ARE approaches without vertical guidance. LOCDME has no vertical guidance, hence non precision. ILS is precision because it has a GS. A new thing is Vnav precision approaches where Vnav gives you the vertical path.

 

The RNPRNAV procedure into LOWI requires special authorisation from the authorities.

The B737 of Lauda/Austrian had that for example. The 777 did not.

But in FSX you can do what you want of course :-)

While you are at it, try the London City approach as well (steep) :-)

 

If you read the thread the link I provided above points to, you will come to realize that is does not matter how well internal system monitor ANP versus RNP (actual navigation performance vs required...). A VOR approach is based on a VOR and you have to tune it and cross check it even if you fly the VOR approach in Lnav.

 

Does it make sence to be cross checking accurate GPS signals with inaccurate VOR signals?......that is something else. But requirement is requirement.

This cross checking requirement might all disappear in the future, but you have to realize that Lnav/Vanv approaches are relatively new to aviation (compared to VOR approaches) so we are in a kind of inbetween time/situation where both old school and modern stuff are used.

EDIT:

Also,VOR approaches and Rnav approaches are designed based on different requirements.

An Rnav approach for example gives you the runway coordinates on the approach plate. You have to check the printed coordinates against your FMC database coordinates for this point. This to make sure that the magenta line actually takes you where you want to go and not to the parking lot next to the airport!

A VOR approach plate does not (have to) provide coordinates as it is based on you following your needle.

If your VOR coordinates are not correct in the FMC, cross checking with the VOR needle will save your day!

 

Anyway, change takes time in aviation!

The might have. IGS at Kai Tak or LOC/DME in Innsbruck have vertical guidance, even though they are non-precision.

 

They are non-precision because they will not align you to land precisely like an ILS would do.

 

LOC/DME has vertical guidance? You're right about Kai Tak though, (and it's not the only offset IGS type approach iirc) so thanks for the correction.

 

 

LOC/DME has vertical guidance? You're right about Kai Tak though, (and it's not the only offset IGS type approach iirc) so thanks for the correction.

 

Innsbruck LOC/DME has. Of course this is a special case.

 

 

 

 

The RNPRNAV procedure into LOWI requires special authorisation from the authorities.
The B737 of Lauda/Austrian had that for example. The 777 did not.

 

It would hardly make sense for the 777 to have the authorisation, that makes sense.

I don't see an iherent reason not to fly the localizer approach though.

 

 

 

If you read the thread the link I provided above points to, you will come to realize that is does not matter how well internal system monitor ANP versus RNP (actual navigation performance vs required...). A VOR approach is based on a VOR and you have to tune it and cross check it even if you fly the VOR approach in Lnav.

 

If you recieve authorisation to fly the approaches with LNAV/VNAV only, you should not need to crosscheck raw data. Of course it would involve a pretty big investment in certification, traning etc.

Innsbruck LOC/DME has. Of course this is a special case.

 

 

 

 

It would hardly make sense for the 777 to have the authorisation, that makes sense.

I don't see an iherent reason not to fly the localizer approach though.

 

 

 

If you recieve authorisation to fly the approaches with LNAV/VNAV only, you should not need to crosscheck raw data. Of course it would involve a pretty big investment in certification, traning etc.

Innsbruck LOC/DME has. Of course this is a special case.

 

 

 

 

It would hardly make sense for the 777 to have the authorisation, that makes sense.

I don't see an iherent reason not to fly the localizer approach though.

 

 

 

If you recieve authorisation to fly the approaches with LNAV/VNAV only, you should not need to crosscheck raw data. Of course it would involve a pretty big investment in certification, traning etc.

Come on now....a LOC/DME per definition has no Glide Slope = no vertical guidance. Not in LOWI either.

If it had a GS it would be called an ILS!

 

Any conventional approach (based on a navaid) HAS to be cross checked!

Lnav/Vnav certification has nothing to do with it.

 

Our 777s are certified Lnav/Vnav (ofcourse) and we SHALL cross check when we use Lnav/Vnav to fly a VOR/VORDME/LOC/LOCDME etc.

 

An Approach needs to be designed as an RNAV approach or an RNPRNAV approach to not have to cross check with needles.

That is why I said read the link....I explained it before.

 

 

Come on now....a LOC/DME per definition has no Glide Slope = no vertical guidance. Not in LOWI either.
If it had a GS it would be called an ILS!

 

Rob, have you been in LOWI lately? Sim or RL?

 

Anyway section 2.19 of textual Austrian AIP - LOWI

 

Unfortunately I don't have at hand a video where it can be clearly seen, only when references can be heard from cockpit chatter, but unfortunately it is in Slovak...

 

 

 

Any conventional approach (based on a navaid) HAS to be cross checked!
Lnav/Vnav certification has nothing to do with it.

 

Now I don't want to sound unnecessarily harsh, but should I probably send the CAA people who approved that procedure to go read that link?