my question is the use of IAN on an RNAV RNP approach with RF legs. Can you use IAN? My understanding is Boeing says it is not recommended in descending turns as the descent profile is not assured. Does anyone have any more information on this? Would appreciate any references

Not convinced by this. Do you have an FCOM reference?

Common localiser frequencies for the reciprocal runway would cause an RNAV approach to end in tears.

whale2guppy

No, IAN is for straight in approaches. Think NDB/VOR or RNAV Z approaches. RNP with curved legs should be flown using LNAV / VNAV as per the FCOM.

Fursty Ferret

Of course he doesn’t. It’s not possible to get a reference for that kind of rubbish​​​​​​…

IAN is a way of using FMS vertical glide path when ILS glide path is not available. Airbus has a similar system and calls it FLS or Flight management Landing System. It may be a VOR approach where vertical guidance is not coded in FMS, what's called managed in Airbus or using ILS localiser only approach because GS is not available. It cannot be that IAN will use ILS when you want to do a VOR approach. because which minima will you use. It helps flying a non precision approach ILS like with FD LOC and GS indications but from FMS. It cannot be used for RF leg approach.

what is the definition of a “straight in approach”? I saw somewhere that this is around 3degrees of centerline. Is that correct? Does that mean you shouldn’t do an IAN on an OFFSET approach?