[ This is the first of a series of flight blog entries; each one will both cover what I did in a specific flight and try to explain what it means. It’s as much a review tool for me as a means of sharing my enthusiasm about aviation; feel free to leave questions in the comments…]
Tuesday morning I was scheduled to fly a cross-country flight with Andy. As with so many other things, “cross-country” means something completely different to normal people than it does to pilots. The FAA defines cross-country time in part 61 of the Federal Aviation Regulations (FARs). The magic distance in this case: 50 nm (that’s “nautical miles,” as opposed to “statute miles”, which normal people use for highway distances and so on.) In order for a flight to count as a cross-country flight towards your private pilot license, you need to fly at least 50 nm from the point of origin and land at an airport.
I planned a route from Palo Alto, whose airport identifier is KPAO. The “K” means it’s an airport in the US. Canadian airports are tagged with C, Mexican airports with X, and so on. This identifier, interestingly, is the same as is used for radio station call letters– go figure. Anyway. my route was from KPAO to the small airport in Columbia, Caifornia; its airport identifier is O22. (No K. Why? It’s a small, non-towered airport, and their identifiers don’t get the national prefix. Other examples include E16 down in Gilroy and 1M3 near Ardmore, Alabama.) The route would take us from Palo Alto to Columbia, then back to Tracy (KTCY), then back to Palo Alto. Here’s what it looks like:
Andy wanted me to plan on using two radio navigation aids– known as VHF omni-range stations, or VORs. You can see ten in the upper right of the map above– they’re circles with a compass rose surrounding them. Lots more on VORs in a future installment…
What does it mean to plan a cross-country flight? Well, the FAA has a useful answer. Section 91.103 of the FARs has this to say:
Each pilot in command shall, before beginning a flight, become familiar with all available information concerning that flight.
“All available information” explicitly includes data about weather, runways, takeoff and landing distances (which are influenced by terrain, weather, aircraft loading, and runway conditions), and anything else that you need to know to conduct the flight safely. In the case of this flight, that meant getting a weather forecast (a subject for a future acronym-filled post), reviewing the airport data for Tracy, Columbia, and Palo Alto, plotting a course using landmarks for dead reckoning, and calculating estimated time and fuel usage for each leg of the flight. There are electronic tools that can automate flight planning, but I didn’t use any of them; I did it the old-fashioned way, using a chart, a pencil, and a Jeppsen navigation log like the one shown below. (OK, I did cheat; I used an Excel version of the nav log.)
Tuesday morning dawned clear and cool; when I got to the airport, there was a scattered overcast near the airport but it was clear to the east, where we were going, so off we went. During the preflight, I’d programmed the G1000 with the planned route of flight so that it could give me steering cues… as long as it was working, that is. We took off to the north, made a right turn at the west end of the Dumbarton bridge (because that’s the standard departure procedure for this airport– if everyone taking off goes to the end of the auto bridge, and all the incoming traffic flies to the parallel train bridge nearby, it’s easier to keep the streams separate.) Winds were fairly light. The G1000 has a nifty display that shows you the winds aloft, which is good because the winds aloft forecast was wildly off.
One important thing I learned: how to correctly adjust the air/fuel mixture at altitude. This is too complicated for me to explain here, but basically if you adjust the mixture adjusted properly you’ll get the optimum balance between engine temperature (too high or too low are both bad) and fuel consumption. The G1000 makes this pretty easy; it has a separate mode for leaning, so you bring that up and start tweaking the mixture until you hit the desired temperature. Anyway, this was a fairly new procedure for me.
I had no problem flying to first the Manteca VOR and then the Linden VOR. All the while I was keeping track of our position on my paper chart too, which was useful because Andy simulated a failure of the GPS moving map display so that I had to rely on my primary VORs and charting to figure out where we were. My first problem came when we were about 10 miles away from Columbia and I needed to spot it… and couldn’t. Take a look at this picture to see why (the full-size version is better):
See that yellow line: that marks the distance I was from the airport. At my altitude of 3500′ it was nearly impossible to see if you didn’t already know where it was. Which I didn’t. Luckily I’d noted that I needed to call Columbia’s traffic radio at 5nm west of the reservoir, so when I saw the reservoir I knew I was in the right general area. Andy had to point out the airport location, though he later told me that one of the reasons he sends students to that airport is because it’s hard to find.
Another thing about Columbia: there are hills all around it. The field itself is about 2100′ above sea level, which means the altitude at which you fly traffic patterns there is about 3100′. That still seems kinda low with the hills about; it is deceptively difficult to accurately judge your altitude above forested, crenellated landscape. I made a decent landing despite that, then we taxied back and took off again to Tracy, or so I thought.
I still didn’t have a working GPS, but thanks to my nav log I had navigational references, courses, and so on to help figure out where I was going so that wasn’t a big deal. There is very little to see in that part of the world, too– if you try hard you can see Copperopolis but that’s about it. On the way, Andy decided it would be fun for me to have a simulated emergency so he pulled the engine power to idle and said, rather cheerfully, “You’ve just had an engine failure.” Then he sat back and watched.
There’s a procedure for this, of course, in which I’ve been well drilled. First thing: fly the airplane. Every airplane has a characteristic speed known as Vy. This is the best glide speed; in a Cessna 172, Vy is 68 knots, and you’ll get about 9 feet of forward flight for every foot of altitude you lose if you maintain that speed. If you go faster or slower, you don’t get as much glide.
Step 2 was to figure out where to go. A little knob-twisting on the G1000 revealed that Oakdale was the nearest airport– about 7 nm away. Andy quizzed me to see if I thought we could make it; at 4000 feet, if I maintained Vy then we should be able to glide about 36000 ft, or close to 7nm. So that’s what I did. Meanwhile, step 3 was to run through the checklist for a failed engine, including checking the fuel tank selector, making sure the fuel cutoff valve wasn’t engaged, simulating a Mayday call, and– oh yeah– doing all this while maintaining the right speed and calling Oakdale traffic to let them know we were on the way in.
I arrived at the arrival end of the runway a little higher than I would have liked; Andy converted my approach by extending our downwind leg and landing in the opposite direction. I made another good landing, then we discussed the importance of flaps, which I hadn’t used enough of. More flaps would have increased my descent rate enough so that I wouldn’t have been too high on the approach end. We took off again and flew back to Palo Alto without any further emergencies or tomfoolery, then I made another good landing and put the airplane away.
Key things I learned during this lesson:
- If you have a thorough nav plan, then losing your GPS is no big deal. Even if I had lost my VORs I could have navigated to Columbia and back to Palo Alto (though in that case I’d’ve stayed at Columbia until the airplane got fixed; in this plane, the avionics are all integrated and anything that would kill GPS and the VORs would make it unairworthy until repaired.)
- Vy is critically important. There’s an old chestnut: “speed is life, but altitude is life insurance.” Very, very true.
- I have a hard time judging my approach heights at airports in hills. This is just something I’ll have to get used to.
- I need to get better about remembering to use my flaps during emergency landings. They’re part of the flow check, and my tendency is to check them off and then not return to put them down later when I need them.
3 responses to “KPAO-O22-KPAO, 15 May”
I don’t know if it’s the same as radio station call letters, Paul. I’ve never heard this. Where’d you get this information?
Best glide speed is NOT Vy. It may be close, but it’s not Vy.
Ack! Fred, you are of course right; I know the difference between Vy, Vx, and best glide. I blame a brain fart from overwork.
As for the radio station call letters: I was wrong about that. The Wikipedia page for ICAO airport identifiers (http://en.wikipedia.org/wiki/International_Civil_Aviation_Organization_airport_code) points out that X isn’t used in Mexico, and that Hawaii and Alaska have their own ICAO identifiers. The identifiers are the same for Canada and the US, which is why I made that bad assumption.