February 16, 2010

The Wrong ALTAM

Just off Oakland's runway 27R at taxiway Bravo — yes, almost exactly where I was nearly run over by that MD80 — we get cleared to depart on 27R. I'm taxiing up past the hold short line and onto Bravo when the tower controller tells me it looks like we're on taxiway Alpha, and to continue on up Alpha and make a right when able back onto the runway. By this time I'm actually on 27R's threshold (on the stripes, actually), and turning to line up for departure. I'm momentarily confused — the suspicious part of my brain's asking "what's he really trying to tell me?" — but eventually respond with something like "Uh Tower, we're on 27R at Bravo, on the stripes…". Not for the last time this evening, we hear a resigned "Never mind…" from a controller, and we're on our way. As we depart I wonder if he's working from the south tower rather than the usual north tower position — as with the MD80 incident, south tower controllers can't actually see that part of the airport directly. Oh well; I still think that part of the airport's an accident waiting to happen.

Somewhere miles further down the line 5000' up in the darkness heading towards for Tracy (KTCY), the NorCal Approach controller vectors us for V244, then helpfully tells me "information Lima is current". Lima? We're heading towards an untowered airport without an ATIS. Have I missed something important? After a little prompting from John (sitting in the right seat), I blurt out to NorCal that we're heading for Tracy. We get that classic "Never mind…" again from the controller and head towards V244.

A few minutes later NorCal asks me how I'll be approaching Tracy (KTCY). I shoot back that we'll do the RNAV RWY 12 approach with ALTAM intersection (on V244) as the initial approach fix and a full stop at Tracy; we'll cancel IFR when we're close to JENEG, the final approach fix. A few seconds later I get the right words of approval and load the approach into the G1000 as part of the current flight plan. Without giving it much thought I leave the approach loaded but inactive — plenty of time to activate it later. In any case, a few seconds later the controller gives me "direct ALTAM" before we intersect V244, so (again, without giving it much thought), I find ALTAM in the existing plan, and punch in direct ALTAM. We head towards ALTAM, correctly enough, but as John reminds me a few seconds later, I've really hit "direct" for the wrong ALTAM. I should have hit direct for the ALTAM that's part of the approach rather than the ALTAM that's part of the main plan. Yes, the G1000's just not smart enough to know that the two ALTAM's are one and the same waypoints, and — unlike the clunky old KLN 94, which will tell you it's deleting one (or more) of the identical waypoints as it activates or loads the approach, the G1000 will happily sit there unaware of what you're really trying to do, and is quite unable to get its head around the existential crisis involved in having two ALTAMS. Not a huge issue, but the behaviour of the G1000 in the resulting flight plan configuration has puzzled me several times in the past until I nutted it out on my own. Not for the first time I wonder out aloud about the way Garmin's engineers have simply seemed to ignore the human factors associated with the otherwise excellent unit. I find it hard to imagine me doing much serious IFR flying nowadays without it, but nearly every flight there's some … oddness … lurking in unintuitive menu functions, wrong-sense knobs, weird layouts, etc.

Literally seconds later NorCal clears us for the approach, with an immediate descent to 4,000', then a restriction on crossing the OYOSO intermediate fix at 4,000', i.e. 1,000' above the published altitude. I wonder out aloud about why, thinking NorCal's probably got traffic below us or a hold in progress or something. No big deal, but I look at the chart again and mentally calculate the required descent rate past OYOSO — crikey, I think, that'll be about 1,200 FPM at our current speed, i.e. a precipitous drop in a C172 like this. I don't mind that on a clear still night like tonight, but it's not something I'd feel comfortable with in Very IFR weather.

We're passing ALTAM at 4,000' heading for OYOSO, when John decides to (politely) ask the controller why we've got the crossing restriction. The controller comes back quickly (and a little defensively) with "well, 4,000' is my MVA in the area"; to which John responds with the observation that the published altitude for the ALTAM OYOSO transition is 3,000' (me, I'm thinking "Gawd, John — don't question him! They'll send out the F16s!"). We get a non-committal answer to that one, so we putter on at 4,000' towards OYOSO. After a short period of radio silence from everyone concerned, the controller comes back to us unprompted with a "descend and maintain 3,000", and down we go. John says that he suspects the controller's not looked at the plate for ages, and on a not-particularly busy set of (relatively-new) approaches like these into Tracy, it probably just doesn't matter that much, but it's always reassuring that I'm not the only one making (little) mistakes in this business….

As we turn towards the final approach heading at OYOSO, the G1000 suddenly flashes up the message "Approach not active!" across the main HSI and the display goes into approach-not-active mode. Quick as a flash I look at the G1000 flight plan window (did I forget to correctly activate the procedure? No, it looks fine) and then the autopilot, start thinking about aborting the approach, then look up at the main display HSI again. And everything's just fine, all back to normal, with the approach active and the autopilot turning us correctly to the final approach segment. I watch the unit like a hawk for the rest of the way in (well, I always do that, but never mind, it's the thought that counts). We discuss this later, back on the ground at Oakland; I suspect we had a momentary WAAS integrity failure, possibly due to antenna configuration in the turn, or maybe a cranky antenna. John has a similar theory; I guess we'll never know.

* * *

Little errors and issues, for sure, especially on what was essentially a night VFR currency flight done as an IFR exercise under the hood in beautifully-clear and warm weather, but (again) it's weirdly heartening that it's not me that's making all the errors, and that nothing really disturbed my calm or caused me to do much more than blithely ponder the Big Issues while under the hood.

After canceling IFR and landing nicely at Tracy, we remain in the pattern for some night currency landing work, with John getting a couple of his own landings in (not bad, not bad :-)), and then depart back towards Oakland. The RNAV 27L approach back into Oakland is familiar and easy, and after a little over an hour and a half of very pleasant and enjoyable flying, my various FAA, insurance, and club currencies are up to date for quite some time again.

* * *

John's brought along his iPhone with the new Foreflight chart setup (and much more). I use the older Foreflight (without charts) myself, and I'm mildly curious how useful the charts are in a working cockpit. I'm also a bit suspicious that I'll find the setup distracting, but when — in response to a mild problem I'm having getting the Cessna's overhead lights to properly light my paper approach plate on the yoke clipbpard — John sets his iPhone up for me to my left with the suction cup against the window, it's actually fairly easy to use, and not at all distracting. In fact I have to remind myself that it's there, and remember to actually use it. After a while it felt fairly natural, and with a bit of positional adjustment and practice, I'd definitely give it two thumbs up for approach chart display and access, at least. I think in the long run it's definitely likely to be in my virtual flight bag….

[Note added 1 March: as John notes in his comment on this article, it wasn't in fact the Foreflight chart software on his iPhone, it was GoodReader with approach charts from Nacomatic.com — thanks John…].

2 comments:

John Ewing said...

Truth be told, it wasn't ForeFlight that was displaying the approach charts (though it can do so). You were actually using GoodReader with approach charts from Nacomatic.com.

The tip off is the lack of any border on the display.

Mark said...

How nice of that control tower to give you a momentary surprise with the issued restriction.