RNAV fix substitution

I am sure, bookworm, of you being familiar (but some others here perhaps not quite) with Australian reservations concerning this version of the FAA’s AC 90-108. Of special concern was the absence in this Advice Circular of any meaningful recommendations/advice regarding the provision of acceptable separation standards in accordance with the nominated flight plan capabilities. See Substitution of RNAV for Conventional Aids

I must be missing something but I thought that

was already common practice and has been for at least 10 years

Is the issue that

• Commercial operators cannot use a GPS to fly say a VOR approach if the VOR is dead. Currently they can fly such using the FMS but the VOR has to be working.

• ATC cannot use a navaid as a waypoint if the navaid is dead, which restricts their options – but they already routinely do this by sending you to WPs which are way outside their DOC e.g. DCT to a VOR 200nm away

I don’t understand the separation issue.

Flight Plan 2012 still requires that the flight plan contain the equipment that the aircraft carries, rather than its capabilities. The outcome of this policy is that aircraft cannot include their capabilities to fly conventional enroute, terminal and approach procedures on the flight plan, and in turn, ATS cannot technically apply conventional aid separation standards to these aircraft. This can impose significant operational restrictions and costs on operators.

I am sure one of the other people frequenting this Forum would be able to provide more apt commentary on this matter and how it is dealt with in Europe.

…frequenting this Forum would be able to provide more apt commentary on this matter and how it is dealt with in Europe.

I can’t do much research right now (sitting in the aircraft waiting for passengers and typing from mobile device…) but here, BRNAV (RNP5) capability is a prerequisite for flying IFR in controlled airspace. So this much is guaranteed once you file your IFR flight plan. And for PRNAV (RNP1
) capability there is also a code letter in your equipment field, independenty from the kind of equipment with which this is achieved.

There appears to be no scenario (yet) where ATC act differently on anything you put in your flight plan equipment list.

In fact I don’t even know if ATC (enroute or terminal) even see your equipment list.

I recall asking about this in an ATC forum a few years ago and the replies were all as above – except an ATCO from Australia who said they see the equipment and might act accordingly.

Obviously Eurocontrol can and do validate (or not) routes based on what you put in there, so e.g. non 8.33 and non PBN and non RVSM FPs get thrown out in the corresponding circumstances, plus some countries throw in extras like banning “I” to/from a non-IAP airport, and the recent case of EDMS shows that transient restrictions can also be implemented. But there is no obvious evidence that ATC care about anything you have filed… Do they query a request for say FL350 from a non RVSM aircraft? If so then they must see at least that part of the declared equipment.

Do they query a request for say FL350 from a non RVSM aircraft? If so then they must see at least that part of the declared equipment.

I don’t think they can see if you are RVSM but you are obliged to tell them.

I would be interested as well as to what the risk is. Here in the US, with a lot more traffic, this has never been an issue.

Shortly I will be seeing an acquaintance of mine who has been intimately involved with issues mentioned in the flimsy I quoted in my post #02. I will ask him for his expert comments before venturing to interpret here the concerns voiced in this “shorthand-style” document with any authority. Please, give me few days….

In a meantime, you might be be interested in reviewing the change to “equipment descriptors” used for flight planning in Australia. This change was AirServices’ Australia response to “ICAO Flight Planning Amendment 1” (that was itself adopted, I believe, after lobbing by Australian delegates).