IFALPA RNAV Visual statement

[divinehover]

IFLAPA recently issued a statement regarding RNAV Visual approaches. It appears there aren't in favour of this type of visual approach technique. What I'm trying to understand is why. I fly both RNP-AR and RNAV Visual procedures and I fail to understand the threat posed by an RNAV Visual approach. Surely a coded FMS procedure which ensures track predictability and terrain clearance is preferable to a Mk1 eyeball approach. I'm certainly not advocating that pilots should not be able to fly good old fashioned visual approach. In fact I believe it's a dying art that needs to revived in some parts of the world, but I also believe there places where a well designed RNAV Visual can be of great benefit to both operators and ATC.

Have there been instances where RNAV Visual have led to incidences or accidents that might have prompted IFALPA to adopt this view?

[lederhosen]

They are not against them in principle and once you are familiar with RNAV visuals I think most people agree they work well. What IFALPA is pointing out is that there is a lack of standardization and appropriate training for what can actually be quite complex approaches. I am pretty familiar with the Tel Aviv 30 approach. But I suspect it would make an interesting line check for a long haul wide body crew that had not been there before.

[RAT 5]

Could someone please elaborate what this approach is. I know what an RNAV approach is, but have not flown one. I know what a visual is and have flown 100's. Could this be some kind of cloud break procedure to a visual manoeuvring onto a mid-length finals?

[lederhosen]

Just google IFALPA RNAV visual.

[Intruder]

I don't see any problem, as long as you follow the guidance given on your Nav Display. If we can do RNAV approaches in IMC, why not in VMC?

Looking at it another way, it gives you BETTER guidance than a simple "Cleared Visual Approach" clearance.

[7478ti]

This discussion is a good example why for modern air transport we ought to be flying RNP based procedures all the time, every time, IMC, VMC, day , night always. The paths are defined to be safe to the TDZ all the time, and even back out, in the event of a balked landing, even with an engine failure or first nav failure, and the training is always addressed, data bases are verified, and the vulnerability of Asiana 214's lack of having a safe well defined vertical path and seeing displacement from that path as being readily apparent to every on-board duty pilot goes away forever. Hopefully any remaining training concerns about using FMS visuals (until RNP based procedures are eventually implemented) will be soon addressed?

[reynoldsno1]

I fail to understand the threat posed by an RNAV Visual approach. Surely a coded FMS procedure which ensures track predictability and terrain clearance if preferable to a Mk1 eyeball approach.

We seem to have a number of apparent contradictions here ... a visual approach is a visual approach, and therefore the eyeball is required. Visual approaches do not include specified terrain clearance - that is what the eyeball is for ...

[Capn Bloggs]

This discussion is a good example why for modern air transport we ought to be flying RNP based procedures all the time, every time, IMC, VMC, day , night always
On particularly the first chart posted by OK465, I very much doubt that an RNP-AR approach could be designed over that ground track for "every time, IMC". It looks like it is essentially a visual downwind and close left base; wouldn't that be far too close for a "proper" RNP approach, Aterpster? I would wager that this was designed to fit in with tight airspace; the alternative, a "proper" RNP approach, would cost more and probably complicate the surrounding airspace.

We do hundreds of "RNAV Visuals". They work well. If a crew can't follow a set of waypoints (particularly if they come from a database procedure), with an auto-generated VNAV path to the threshold or at least the base turn point, then perhaps training should be improved...

I will say that here, our "RNAV Visual" approaches aren't flown by international crews. They do a full instrument procedure.

[aterpster]

Capn Bloggs,

On particularly the first chart posted by OK465, I very much doubt that an RNP-AR approach could be designed over that ground track for "every time, IMC". It looks like it is essentially a visual downwind and close left base; wouldn't that be far too close for a "proper" RNP approach, Aterpster? I would wager that this was designed to fit in with tight airspace; the alternative, a "proper" RNP approach, would cost more and probably complicate the surrounding airspace.

Correct. Mr. Imrich knows about minimum lengths of TF to TF legs, depending upon course angle change. Make it too short and the FMS will throw up its electronic hands. And, there is a limit on making RF legs fit as well. Their respective radii cannot result in defined excessive bank angles nor can the radius be less than the RNP value being used. The RNAV visual at Ben Gurion Airport has TF legs on the turn to base and final that grossly violates RNP requirements.

RNP is indeed performance based navigation with accuracy and repeatability. But, there are defined limits on what an FMS can do to "stay on the rails" so to speak, TF or RF legs.

Finally, not all airplanes by any means, have the necessary redundancy and sophistication of FMS and avionics to perform safely at RNP values of less than 0.30.

Finally, at some locations terrain and other obstacles are the ultimate "show stopper."

[lederhosen]

In Tel Aviv's case I would substitute issues for obstacles in the last post. The interesting thing is that in daytime this appears to be pretty much the most common approach to this major international airport. Were it not for other issues it would be a lot easier to land off the ILS on the more northerly runway and use 30 for departures thereby not having to taxi round half the airport before takeoff.