foumanchu

The only thing I can find is the autopilot is capable of maintaining altitude in ALTS mode with an overshoot of less than 40 ft.

I would think that every autopilot has some kind of overshoot tolerance and that is still acceptable when using ALTS to capture the MDA.

I have a feeling that the technique in question started from someone that is confusing adding in a buffer like you would to get a DDA on CDFA type profile. That of course is to allow for the decision to continue or go-around on a non-precision like you would for a precision approach.

galaxy flyer

Do you fly constant angle to circling approaches? Yes, you don’t fly circling approaches, but others do.

GF

Adlerdriver

I’m not sure what you’re trying to say to me GF.

zondaracer

We also do a dive and drive to a circling maneuver (VMC only of course).

galaxy flyer

Bit of a jab in that circling is the only place “dive and drive” (dive to MDA, ALT CAP, drive to visual) might be useful, but airlines don’t circle.

GF

Adlerdriver

Okay - this thread has veered of topic a bit, probably in part due to me.

We started with "does anyone buffer MDA due to autopilot limits". When someone offered a blanket statement about rounding, I countered but unfortunately used a blanket statement of my own.

After that, I was truly asking if zondaracer's company still trained for D&D out of pure curiosity because maybe it's not as uncommon as I thought. I'm pretty sure it's been at least 8 years for me personally since I did a D&D in the sim. Last one I did real world was probably 15 years ago into SAN.

Now we're talking about circling approaches....Okay. A much, much smaller subset of the non-precision approach referenced by the OP. But, why not?

IMO, they are pretty rarely used unless there isn't any other choice. Why would anyone do that if there's a straight in type approach available to the runway they want to land on?
Unless my iPad doesn't show all the Aspen approaches, it looks like circling is your only option if you have to shoot an approach. I think we all can agree that's pretty unusual. I'm sure there are other fields like that, but my guess is that most airline pilots (vs. 91 types) aren't going to find themselves flying into that many fields where circling is the only way to get in. But if your 121 outfit or corporate flight department services a field like that, then I guess you're still going to train to D&D.

It looks like United and Delta both service KASE, so wouldn't that make them (or the sub-contractors that actually fly into ASE) airlines that actually do circle?

I can't imagine why anyone would fly a constant angle approach to a circle... wouldn't that just make the whole thing more difficult, possibly get tight and have to miss? It seems like getting down, getting visual and setting up the final approach would be the better option, especially if you're flying the approach to a different runway than the one on which you intend to land.

galaxy flyer

Adlerdriver,

When the “dive and drive” mention, I had flashbacks to the JFK 04L or R VOR approach, circle to 31R in the Global sim profile. I did that damned thing dozens of times in initials and recurrent. The briefing was all questions, like; “describe D&D, how to set up the panel, what ALTS settings, how to circle?” At first, interesting, later, not so much. The circle to 29 at EWR was a change that was a challenge, then the circle to MEM was pretty simple, lots of airport to look at.

ASE is interesting, alright, but if I had the slightest doubts, it was off to Rifle.

GF

zondaracer

SkyWest does all the flights for United, Delta, and American into KASE, and there is an approach with a straight in MDA that won't show up in your plates unless you have special authorization.

We also fly into KPSP, and the CRJ guys only have a VOR/GPS approach with circling minimums as an option. The E175 guys have an RNP approach that they can use. We have a couple airports like this.

Adlerdriver

Due to equipment limitations with that particular a/c?
Do you know how they fly that VOR approach?

zondaracer

http://155.178.201.160/d-tpp/1812/00545VGB.PDF

It's a dive and drive with a visual maneuver to land. You can do it either VOR or with the GPS. The CRJs at SkyWest are not RNP0.3 approved.

I read that you can get a CRJ approved for RNP approaches with the correct dual FMS hardware and software, but not all of our CRJs have dual FMS (at least not yet), and I don't even know if it is the approved FMS that is being installed for the capability.