Achim,
many ILS approaches now have a procedure turn (IAF over or near the airport, outbound, procedure turn to intercept final), so I wonder why you would fly those manually. Or maybe I am wroing to call that a procedure turn?
Jason, yes, “roll steering” is the official explanation. But since the CDI today in a PFD uses just the same data there’s really no difference anymore between NAV and GPSS: Know what an Avidyne technician told me? That they kept the GPSS button ONLY to make the transition from the S-TEC 55 autopilot (which has this key) smoother, so it wouldn’t “confuse” pilots. I could not believe this and investigated inside COPA. Result: Better only use NAV MODE all the time, because in NAV MODE it will fly both the GPS FPL and the ILS …. while in GPSS it will not intercept the Localizer!
I think that concept has some flaws.
Like the interesting question why it has a GPSS key at all when it flies just the same in NAV mode – no actually much better! Actually its sibling, the DFC100, part of Avidyne’s R9 version of Entegra has NO GPSS key anymore. Now guess why …
Because of the GNS430. Like I mentioned, you can have the DFC90 fly a GPS flight plan from your 430 while your 430 is switched to VLOC, i.e. displays a VOR on the CDI. It’s one of the best features of the DFC90, I can no longer get this dreaded GPS/VLOC mixed up. If I had it in NAV mode, it would follow either VLOC or GPS, depending on the GNS430 mode and that sucks. The DFC100 has no GNS430 involved…
“press either HDG+NAV” or “HDG+APPR” …. I find it ridiculos that I can press two different combinations of keys to get to the same result.
The opposite, I like it when two different ways of thinking allow me to get to the same intended solution. Approach mode is an automatic thing with the DFC90, therefore you can use either NAV or APPR. APPR before established is the same as NAV with APPR armed. When on NAV but inside an approach procedure (i.e. approach loaded on the 430), it will enable APPR mode in due time.
many ILS approaches now have a procedure turn (IAF over or near the airport, outbound, procedure turn to intercept final), so I wonder why you would fly those manually.
They have them because that only requires a navaid at the airfield and not in the vicinity like before. They are doing them this way because nobody ever flies them in real life. Germany is 100% radio vectored (with the exception of Heringsdorf where the procedure is over Polish terrain and radar vectoring is not available because Poland does not publish an official MRVA which is a requirement for DFS to do radar vectoring).
I thought on the DFC90 GPSS used roll steering while NAV didn’t but has been a while since I looked at it.
That’s not correct. Both NAV and GPSS imply roll steering. When on NAV, it will only use GPS when the 430 is switched to GPS, otherwise it will use VLOC. In GPSS, it will always use GPS roll steering, no matter which mode the 430 is in.
I think that concept has some flaws.
I honestly don’t think so.
I find it much less confusing to simply fly the GPS FPL in the GNS430 in NAV mode (and that’s actually what most experienced Cirrus pilots do) becasue then I only have to switch the PFD to VLOC and set the FC … and it will intercept the LOC AND arm the GS. But it will not do this out of GPSS.
Because of the GNS430. Like I mentioned, you can have the DFC90 fly a GPS flight plan from your 430 while your 430 is switched to VLOC, i.e. displays a VOR on the CDI.
I think that this is actually a bad thing. I accept it is a personal view but I think flying a GPS flight plan while showing an ILS or VOR based CDI is asking for mode confusion trouble.
I think the same. I say this as a UNEXPERIENCED IFR PILOT – but i find that completely confusing and a recipe for disaster. But I think that it’s acceptable to have the AP in NAV MODE and fly both GPS plans and the ILS in that mode. This way I only have to switch the PFD and set the course.
But I have to make some more approach experiments … I admit that with my current level of experience I can’t say something very substantial
Do you consider the CDI to be an important enroute instrument? I don’t really use it at all enroute, only during approaches. I find it very good that I can just press GPSS on the DFC90 and it will fly my flight plan, nothing else needs to be setup. I’ve had this situation too often that I enable the AP (S-TEC) and it would start some crazy manoeuver because once again, I forgot to check whether the 430 is in VLOC or GPS mode.
Integrating devices from 3 vendors which all have their own modes they can be in is a huge challenge. I think the Aspen/GNS430/DFC90 combination is extraordinarily good, mostly thanks to Aspen. With a G1000 and the like you have another level of integration of course but that’s unobtainable for retrofit.
I don’t understand what you mean. If you have a flight plan in the 430 and press NAV it will do just the same as GPSS (the PFD can stay on GPS1).
If you have a flight plan in the 430 and press NAV it will do just the same as GPSS (the PFD can stay on GPS1).
Not if your 430 is in VLOC.
Okay, now I’m even more confused. MY personal problem is that there’s one point i don’t understand, but i don’t know which one. …
