June 26, 2007

WAAS, RNAV, LPV, and All That Stuff…

I learned to fly out of Oakland (KOAK), and really enjoy it as a base for GA flying. It's a large, busy airport with a tremendous variety of airline, commercial, business, and small GA traffic, and the sort of operational support (like 24-hour FBO's and fueling) that go with that; it's the centre of its own full-time Class C airspace (and it has two quite separate towers, but that's just a quirk…); it's close to where I live, an easy 15 minute drive (or 25 minute bicycle ride) on pleasant surface streets; and it's got a nice variety of IFR arrival, approach, and departure procedures (roughly thirty or so by my count).

So when I got the chance to get checked out in the new C172SP with a WAAS-enabled G1000 cockpit at Oakland Flyers with John, I jumped at the chance: not only do I get to fly out of Oakland again (for some of my flights, anyway — I'm definitely also staying with CalAir at Hayward (KHWD)) with a "new" club (OK, they're not exactly new to me — I've known of Oakland Flyers for years, and have always known people who fly with them or instruct there), I got to play with the new RNAV LPV approaches using the new WAAS stuff. And it turns out the 172 had exactly 77 hours on it when I started it up. Cool!

The plane itself really wasn't any different to fly than the G1000 172s I already fly with CalAir, and the actual checkout bits went fine, with the exception that, as John put it, I kept trying to land the thing like a Cirrus (i.e. flatter than usual for a 172). Guilty as charged, although the weird and rough windshear just above 27L's threshold made it difficult to land it smoothly at any damn attitude, 172, Cirrus, or whatever (I got my own back when John later tried an approach and landing and had the same "what the hell?!" reaction over the fence as I did :-)).

So what did I like about the new G1000 and the associated RNAV/LPV abilities? John will probably be posting some of his pix from the flight showing the G1000's chart and airport diagram features, all of which is good from a convenience point of view, and the safe taxi feature (or whatever it's called) was cool, even though I know Oakland's taxiways like the back of my hand. Some of the newer G1000 / GPS features like better turn prediction, more detailed fuel quantity resets, etc., were nice but not especially surprising. Some were mildly amusing, like the new vertical obstruction icons that looked like teepes or campground icons in gorgeous reds, yellows, and greens scattered around the hills in the area — I had to ask John what they were twice before I realised he wasn't kidding about them being tower markers, etc.

Of course it was the WAAS capabilities I was most interested in and that give this unit the most added value for me, and it didn't disappoint. There still aren't too many useful RNAV / LPV approaches in the neighbourhood, but luckily Oakland has a good one (RNAV RWY 27L), and we ambled three times around that approach, twice me flying, once with John doing it for light relief (all under the hood, of course). There's not a lot that's difficult conceptually or procedurally with the new RNAV approaches, so I won't spend much time discussing them here (John's had an occasional series of articles about them, e.g. here); in summary, they're basically GPS approaches with decent ILS-like glideslopes with vertical guidance, and, in some cases, very good minimums (but note: some of the LPV minimums are actually higher than conventional non-precision approaches at the same airport. Take a look at Napa (KAPC) for an example of this). The G1000 made things relatively easy to follow along with and fly; I don't think I'll ever miss the "dive and drive" approach to non-precision approaches if given a chance :-). Overall, rather cool, and definitely the way things should be, if a little unpolished on the interfaces.

As John's discussed elsewhere, the C172 G1000 doesn't coordinate particularly well for vertical guidance with the (otherwise rather nice) King autopilot that's standard with the G1000, which is a big shame — not only couldn't we get the LPV approach to couple in the vertical dimension (which is not too problematic — just dial in a suitable vertical sink rate on the AP), but the same old irritating inability to set things like vertical speed or target altitude with the G1000 (rather than separately on the KAP 140) remained. This is irritating on such an expensive and otherwise smooth and easy-to-use interface (OK, the G1000 interface isn't easy for beginners, but it grows on you. I find it easy to remember the basics, but I still can't remember all the MFD options off the top of my head).

* * *

Before we got to the approaches John threw me an ad hoc hold at SALAD intersection a few miles out from it. A couple of years ago I used to find this sort of thing quite a mental struggle, but this time it just seemed easy: John's handy-dandy way of using the HSI for working out the entry procedure combined with some sort of mental model built up with experience over the last year or two made it just happen. I could even answer the questions John kept asking me about it while I'm under the hood, which is a good sign (and yes, I've still yet to ever be assigned a hold in real IFR flying, but it'll happen one day, in the worst circumstances, for sure).

* * *

At one point the NorCal controller asks me — twice in a row, if I remember correctly — whether I want the RNAV 27L approach or the GPS 27L approach into Oakland. Argh! It's the RNAV (GPS) 27L approach, folks — get with the program! And at least twice NorCal tries to vector me to JOCPI (on Hayward's GPS 28L approach) rather than JUPAP (the intermediate fix or waypoint on the actual approach we were trying to fly); and the last clearance I get for the approach includes the instruction "cross JOCPI at or above 3,300". Hmmm. At least I knew what he meant, and it was VMC out there. Not as bad, perhaps, as one of my previous recent IFR experiences with NorCal when the controller instructed me to descend and maintain an altitude several thousand feet higher than I was already at while vectoring me for the wrong approach. Perhaps the views of the FAA's current staffing problems from The Main Bang and The FAA Follies aren't quite as extreme as some people seem to believe they are….

* * *

Back at Kaiser we see a couple of really expensive brand-new gold-painted G3 Cirrus SR-22s sitting in all their glory on the Kaiser ramp. Looks like some sort of demo day or tour. These things look absolutely tasteless and rather ridiculous in that livery, and both John and I can't help wondering out aloud whether we should go over and ask them whether the doors work properly on the new models or not (if you've flown a Cirrus, you'll probably know what I'm getting at…). I decide against it.

* * *

The new plane's hangared in a real hangar, which is a first for me — the weather 'round here makes outdoors tiedowns fairly benign and very common. It's one of those Port-A-Port things, with a rather creaky handcrank-driven main door; opening up felt like raising some sort of medieval portcullis. I can imagine enjoying pre-flighting this plane under cover — summer 'round here always seems to involve cold wind and cloud :-).

* * *

So after all that, I'm now a member of Oakland Flyers as well as CalAir, and can call Oakland home again when flying. Plus I get access to a 172SP with the new WAAS-enabled G1000. Not bad for a couple of hours' work, I guess.