Saturday, November 29, 2008

Field Trip

Today's student only soloed recently. The ceiling was down to 1700 feet, and the winds were gusting to 21, not exactly his kind of weather. "Let's try again tomorrow," I suggested. "What's the weather gonna be?" he asked.

What's the weather going to be?

It's one of the oldest questions. Not one of the oldest questions in aviation, but one of the oldest questions, period.

So we sat down to look at the forecasts. We teach private pilot students a little about forecasts, commercial pilots a little more, instrument pilots a lot more, and ATP students a little more. A lot of pilots I know sit through this, get enough right answers on the knowledge test, and forget it. "Who cares about the weather," I heard one ask, "As long as I have minimums I'm going." The other version is "Who cares about the weather, I'm going anyway." Never mind the minimums.

But nobody can go always. It depends on the pilot and the equipment. I used to fly a King Air to minimums regularly, but once on my day off I did a quick 180 in my no-gyro Taylorcraft when the visibility dropped to 4 miles (still VFR!); there was no way to find the horizon line between the mist and the snow-covered ground.

So I don't believe that the weather is irrelevant. We sat down to look things over. For fun, I looked at the high altitude prog(nostic) chart; all of these are available from The one to the right is a little later, but still shows the same features. In the west, the jet stream is coming down hard from the north, with speeds approaching 150 knots. But follow that green jet stream to the Gulf of Mexico, where it intersects another green line coming from the Pacific.

"What's that?" he asked, pointing to the apparent intersection. "I don't know," I said. Then the idea hit both of us at once: Let's go over to the National Weather Service office and ask. So we drove across the field.

The door was locked, of course, but I knew they were in there, so I rung the doorbell. Someone came out and gave us a suspicious look.

"Hi" I said, "I'm a flight instructor and he's a student pilot and we have some aviation weather questions." His face lit up with a big smile. "C'mon in!"

So we sat down with a couple of forecasters and lots of high definition monitors. I showed them the prog chart. "Convergence," one said. We knew that, but I had never seen such a large angle. Hmm, they said. What we were looking at was convergence between the polar jet and the southern jet.

They pulled up all of their charts, which showed a closed high over the eastern Pacific, that is, streamlines formed complete circles around the center. I have seen closed lows; they are always a bad sign. But a closed high? But there were lows on either side, forcing the air around the corner to turn east.

We looked at other features of the chart. First, the little "home plate" by Los Angeles says "H 510," meaning that the height of the tropopause, which is where the troposphere and stratosphere meet, was about 51,000 feet. At this latitude, 51,000 feet is very high for the tropopause, even in the summer. "Trop at 51?" someone yelled from across the room. "Weird."

To the east, north of Dallas, the little box says "270", meaning that the height of the tropopause was 27,000 feet, more typical for winter. The gradient, 24,000 feet in a little over 1000 nautical miles, is very steep.

Another convergence zone appeared closer to Hawai'i. "All the tourists are belted in tight and they're not serving drinks," someone remarked. A flight to Hawai'i was going to be rough.

The same was occuring over the Gulf of Mexico. "There should be some thunderstorms forming there," a forecaster said, but there were none in the forecast. My student recited the three ingredients for thunderstorms, "Moisture. Instability. Lift.". Moisture from the Gulf; instability from the warm tropical air, and lift from the convergence. (The chart above is from later, and now predicts the thunderstorms.)

NWS no longer does individual weather briefings; we formed the joint conjecture that that was in order to keep the government from competing with Lockheed Martin Flight Service. They seemed to miss doing it; they worked hard to get the certification, and were convinced (as was I) that they would do a much better job than the LockMart briefer who merely reads the METAR and TAF over the phone, framed by lots of CYA verbiage.

On the other hand, these folks aren't pilots and don't really know what we do. To them, a couple of middle-aged men are flying a rag-and-tube taildragger. "Take some O2 if you go that high," they say, even though I know a lot of middle-aged pilots flying pressurized twins and even turboprop singles.

But we're not meteorologists, either. There's a lot to be learned on either side.
We ended up learning a lot.

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Tuesday, November 25, 2008

Class B with a grain of Salt

Salt Lake City approach and its Class B procedures continue to leave me scratching my head. Continues? See Class B Silliness from back in April. And for years they have been annoying turbine pilots by using an unpublished north departure gate, the Wasatch VOR 005 radial at 60 nautical miles. Locals learn to expect this and to carry a little extra fuel (it adds 15 miles to a flight to Pocatello, for example), but transients are left scratching their heads and reprogramming the FMS while Mr. Big Shot and his trophy wife fume at the delay.

They're still slow to give Class B clearances. Sometimes they'll say "Expect Class B clearance from the next controller," but the legal status of "expect" isn't clear to me, especially when flying under Visual Flight Rules (VFR). Under Instrument Flight Rules (IFR) the situation is different: according to 14CFR91.185, the route or altitude that ATC has told a pilot to "expect" becomes the clearance in the event of lost communications. So, approaching Idaho Falls on a busy IFR day one often hears "Proceed direct Idaho Falls VOR, expect ILS runway 20 approach." If you reach IDA and the frequency has been too busy for center to give you a new clearance (lack of bandwidth is a form of lost communications) you just go ahead and do the approach.

But a VFR approaching KSLC is not an IFR, and a clearance is not a route. Do they think that the "expect" will allow me to enter Class B in the event of frequency congestion? I just don't know. We end up circling in the little notch between the Wasatch Front and the Class B boundary, above the Ogden Class D.

The next annoyance is their use of an unpublished frequency for the tower. General Aviation usually uses the east runway (17 - 35); the tower frequency is published as 118.3 mHz. But now the final handoff from Approach is "Contact Salt Lake Tower on 120.2." This isn't a big deal on arrival, when you are going through a bunch of frequency changes, but departure is different. Before flying in the Class B airspace you need a clearance, and the Clearance Delivery position has helpfully given you a departure frequency along with a transponder code. When my students are ready, I have them switch to tower frequency, then set the departure frequency as the standby frequency, and only then call "Ready."

But now Salt Lake Tower hands departures off to 120.2, rather than the departure frequency that we have been told to expect. So the student, already stressed, does a bunch of knob twisting while trying to stay straight and stay under the altitude restriction. It would be easier if Clearance Delivery said "Departure with Tower on 120.2."

Leaving Class B, we hear "...leaving Class B airspace, frequency change approved, have a nice flight." What happened to "squawk VFR?" I am 100% sure that they do not want us on the same transponder code; they recycle them pretty quickly. So again we have to ask and the frequency is tied up more than necessary and somebody doesn't get their clearance or flies through a localizer due to lack of bandwidth.

And it's not our fault.

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Sunday, November 16, 2008

Broken Stuff

Sometimes broken doesn't mean broken, especially in aviation where, unless you crash, paperwork is the only thing they can hang you with.

The regular curriculum around here is to take private pilot students into Salt Lake City for some experience with Class B airspace. I start this exercise with the assumption that cross-countries are hard, and leave plenty of time to go over the flight planning, flight plan filing, and the like.

The first priority is the airplane: if there is something wrong, catching it early means that it can be fixed while you do the other stuff. And there was something wrong: the little sticker on the tachometer said that an inspection was due in less than 2 hours, but we were planning to fly more than 3. Students need to learn that a missed inspection (especially one involving an Airworthiness Directive) makes an airplane that appears to be perfect into a static display.

Sometimes maintenance pads the value on the sticker, so I called around waking up mechanics. I finally got one who told me that the airplane had 15 hours to go (he must have misunderstood the tail number), but offered to educate me about checking the logs. This was a dig but I let it pass.

So I asked someone from the line crew for the key to the maintenance hangar, but he said that it was impossible to get in. I have flown with this company for almost as long as he had been alive, but I did not know the current Secret Hiding Place for the maintenance key, so I called him on it. He offered to go check.

We turned our attention to the preflight planning process. I've mentioned before that I consider the computerized briefing through DUAT or DUATS to be the primary method, so we sat down at the computer and got a standard briefing. This is much less stressful to the student than talking to an expert on the telephone, and more information is retained. Not in the student's mind, but on paper. We also used the DUATS flight planner as a backup to his paper flight planning, and filed the first VFR flight plan for the day.

There was an extra hour available on the airplane, but there would not be enough time to do the planned triangle, so I suggested that we just do Salt Lake and back to be sure to land within the time constraint. So we loaded up with all of the charts and my portable GPS. (This airplane does not have a GPS, and probably never will, but you can't teach 2008 cross-country flying without one.) "Clear!"

Nothing happened.

"Nothing happened," he said. "Let me try," I said, so I reached over and hit the starter and of course nothing happened.

"Key out, master off, brakes on," I told him, leaving the airplane to investigate from the front. I'm not a mechanic, but maybe there was something obviously wrong with the starter. Nope. I turned the prop a couple of blades by hand and had him try again. I was very aware that I was teaching as well as troubleshooting.


There was no noise from the solenoid, so I poked around in back looking for it, but in this model the solenoid is under the cowling and pretty much inaccessible. The maintenance chief takes a dim view of CFIs removing stuff from the airplane...

"Chris is in the hangar," the line guy said, "I'll go get him."

Chris is in the hangar? There was a mechanic on the field all this time? Geez.

So Chris came over and poked around and declared us to be Broken. For real.

Luckily there was another airplane available, but this was a 172XP, the kind with the 195HP engine and constant-speed prop. So we did the constant-speed prop & fuel injection lecture, and I let my student take it once around the pattern so his first landing in the thing would be while he was fresh, not after his body was filled with Class B cortisol. And, we went back to the original plan, which meant a stop at Logan, where I keep my glider.

The flight went pretty well, Dan got the expected butt-kicking from the Class B experience, and we stopped at Logan to say hi to everyone. The gal (Hi Becky!) who works the line there said "I didn't know that you flew powered airplanes, too! I have so much more respect for you now," in her pleasantly sarcastic way. We checked the weather, watched a couple of auto-tow launches, and took off for home.

In the end we succeeded despite two kinds of broken airplanes. Persistence pays.

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Friday, November 14, 2008

What Teachers Know

Here are two parallel tales about teaching. Mathematics and flying share the tradition of using teachers who have a "knack" for the subject, which is great for students who have the knack.

It as around 1990. I was teaching at a small college in New York State. The Space Shuttle was flying a high-inclination orbit, so I did some calculations and determined that it would be visible overhead. Cool, I thought, and made a flier that explained the trigonometry. I invited people to join me to watch. The problem was that it was mid-Winter with temperatures around 10F/-10C, and the pass would be at 2am. Only one student joined me. It turned overcast and we saw nothing, but it was worth the try.

He went on to get a PhD in Mathematics.

I offer to take all of my instrument students on a long cross-country, the kind involving an overnight and some real weather and real terrain. Most decline; in fact, only one has really gone through with it. He did a great job. The best part was after he botched the ILS approach into Pendleton, Oregon. We landed for a snack and a discussion, and he shook it right off and flew a great ILS into Portland.

He went on to become a captain at a regional airline.

What do teachers know? More and more I think that teachers know nothing, not in the sense that we don't know our subject, but in the sense that we don't know our students' minds. The point of the two stories is that I really managed to get into the heads of two students, but they were like me as far as goals and dedication. Not everyone is like me, or even like you, which is how it should be. But how can we teach people who see things so differently? A private pilot student can become a good pilot even though he may never get an instrument rating, probably won't become a commercial pilot, and will almost definitely never get an ATP. A calculus student can become a good scientist or engineer or economist, even though he may never take any more mathematics, probably won't become a math major, and will almost definitely never get a PhD. Everyone has unique tastes and talents and desires and backgrounds. So by definition the teacher's goals and motivations are, or were, different from the students. What worked for you may not work for them.

Some of you may disagree, but there is an art to algebra. Algebra is actually the simplest thing in the world, much simpler than baking a cake (which I am doing as I write). There are four operations, a fixed rule for deciding in which order to do them, and an associative law that guarantees that everything is unambiguous. Algebra is simpler than music, which has twelve tones, not just four, and all of the complications of rhythm and dynamics and feel. But both simple systems produce an endless range of expression, which is part of what makes them art. There is also art in knowing when to factor, when to simplify, and when to just leave it alone. There is art is in seeing that "3+0" carries more information that just "3", even though they are equal: the former fits into a pattern, while the latter is just a number.

But algebra is different than flying, right? Algebra is abstract, and flying is visceral. That is of no consequence: what matters is that in each case the operation is easy, so learning means learning to perceive, learning where to look and when to look and how far out to focus and to what to expect when you get there.

The teacher's disadvantage is in never seeing what the student sees. There are exceptions, like the two students above, but they began with goals like mine. They're easy to teach. The work and the art are in teaching the student who is completely unlike you by learning and speaking the student's language.

Here's an example. In a Cessna 172, the nose pitches up when flaps are added. "Don't let the nose come up," I say as the student reaches for the flap lever, "Hold this attitude." I watch the windshield view change from grass to clouds, but the student cannot perceive it until the airspeed decreases, which is already too late. How could I have said it differently? Should I insist on rote ("When you lower the flaps trim nose down one turn of the wheel.") That may be enough! It might not have been enough for you, but it may be enough for this student, for now. The commercial student needs to understand the pitch change and explain its aerodynamics; the instrument student needs to apply this knowledge to keep the proper pitch attitude during configuration changes; the ATP candidate needs to correlate this knowledge with other effects of control manipulation.

You need to need to know more than the student; that's why you became an instructor.

I'm afraid that we end up teaching people to do all kinds of things the same way that we teach children to talk: we allow them to hang around and listen, and as they try we offer critiques. It works pretty well for talking, but while a Chomskyite might claim that we are pre-wired to learn talking, and some people appear to be pre-wired for mathematics, nobody claims that we are pre-wired to learn flying. While my twins might have learned to talk listening to me and their mother converse over dinner, my twin-engine students are less likely to learn from watching me and my wife try to synchronize our engines. (If you know what I mean...)

Knowing that just watching isn't enough, we throw stuff at our students. "Here's the theory," we say, giving one each more or less according to individual taste. "Here's a drawing of what it looks like," although we only produce a cartoon. "Here's a silly mnemonic," we say, reciting "True Virgins Make Dull Company." We make up colorful reminders: "Tail in the weeds!" I say before a short field takeoff, meaning to use the full length of the runway.

(In calculus class all these efforts go for naught when the student can only think about how attractive the girl next to him is.)

The airline-oriented flight schools and the military count on their students working hard to make up for any deficiencies in the teaching, but that model won't work in general aviation. Besides, it's inappropriate. So as teachers we must toe the line between discipline and laisser-faire. Most important of all, we have to offer the student what we have to offer and then listen.

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Thursday, November 6, 2008


One of the worst things we do in aviation is putting our experience into little compartments that stay on the shelf until the exact circumstance repeats itself. One example is the pilot who has been flying twins and forgets to keep a landing spot in mind when flying a single. It's a form of complacency.

This came up the other night while flying with a student. We had been scheduled for the night before, but a strong cold front came through, attacking us with ceilings around 1500' and lots and lots of wind. Gusting to 30 wind. The ceiling was too low for a first night flight and the wind was too strong for a student. So we cancelled.

Now we had clear skies and light winds on the ground, although the winds were around 20 knots 1500' above the airport. I gave him the Introduction to Night Flying lesson, and off we went.

I wanted to take him over the city and its reassuring lights first. The winds were favoring runway 21, and the city is east of the airport, so the natural thing is a left downwind departure. But that's where the hills are, too, and I convinced him that it would not be prudent to take off toward high terrain at night with a big tailwind: every hesitation in the turn to downwind and in setting up a crab into the wind would take us toward the mountains. Google Cory Lidle, the Yankee pitcher who hit a building in Manhattan, for a reminder of what happens when you ignore obstacles in high wind.

In the picture, the left downwind departure is red, and the right downwind departure is in green. Each has a crosswind turn, then a distorted downwind leg. The left downwind departure goes directly through a tower 1700 feet above the airport and only about 4 miles away. A 172 can't outclimb that.

The tower approved the right downwind departure to cross overhead, and soon we were over the city. The city is in a triangular valley, and I told him to fly closer to one side so that we would have room to turn around. There was a long cloud over the city, surprisingly low, but not low enough to prevent VFR. Just one long cloud, running parallel to the valley, illuminated by the lights below.

Any glider pilot would recognize the cloud, but my glider knowledge was in a compartment back home, not in the airplane. It was a rotor cloud, sometimes called a roll cloud. The picture to the right, from the FAA's Glider Flying Handbook, shows what was happening. The strong wind from the west -- the same wind we had just discussed -- passed over the mountains at the edge of the valley producing a strong downdraft (we found it), a rotor, and a strong updraft (we found that, too).

The thing is, the rotor can be really turbulent, and this one was. So our smooth introduction to night flight became an object lesson in the positive and negative effects of mountain wave. In the end it was fun, but for a few seconds there I could that my student had that uncomfortable feeling in the pit of his stomach, the one that comes up when there is unexpected turbulence.

I've written about complacency before: see Missing the Signs, back in September, or How Far Can You Go? in August. Writing about complacency is a weak way of avoiding complacency, better than nothing. But avoiding complacency takes more; checklists help some, but it almost takes minute-by-minute vigilance to guarantee success. Do you daydream while your student checks the magnetos, or do you watch carefully to make sure that both are on before takeoff? Do you believe that your student looked outside during the clearing turn, or do you look, too? Do you yawn through the pretakeoff checklist, or do you sit there with a smile plastered on your face reciting "Controls Instruments Gas Attitude Runup" to yourself while you verify that each has been done?

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Sunday, November 2, 2008


14CFR § 91.13 Careless or reckless operation (a)Aircraft operations for the purpose of air navigation. No person may operate an aircraft in a careless or reckless manner so as to endanger the life or property of another.

91.13 is the FAA's catchall regulation. If you hurt someone or something, then that is prima facie evidence that you violated the regulation. I came close today, close enough to send in an NASA Aviation Safety and Reporting System form. I also sent a letter to the chief pilot of the company that operates the airplane.

It was a miserable day, with heavy rain and strong gusty winds. A good day for ground school, which we did. As a reward, Dan wanted to look inside one of the King Airs in the tightly-packed hangar. I had flown both of them a lot, but it has been a whie. I picked the EFIS one so he could see a glass cockpit.

I put him in the left seat, did a quick cockpit scan to make sure the switches were in the right position, and turned on the battery. I showed him how the stall warning test moved the little vane on the wing, and then had him turn on an invertor and the avionics master.

Immediately I knew that something was wrong. "Do you hear something?" I asked, but that wasn't fair because Dan had never been in the airplane before. There was a strange whirring noise from the nose of the airplane. I thought it might be the air conditioning, but that was off. The aft blower was off, but I turned it on anyway, and was reassured to hear more noise. The new noise was rhythmic, with a 4 or 5 second period.

Still puzzled, I turned on the EFIS. It takes a few seconds to warm up and do its internal tests. As soon as the multifunction display came alive I saw the problem.

The weather radar was on! We were radiating inside the hangar!

I said something unprintable and turned the radar off. Looking ahead, we had been irradiating the auxilliary tank of the King Air in front of us.

We had been irradiating a fuel tank!

By blind dumb luck, the fuel was far enough away and well enough shielded, the radar we weak enough, and the exposure time was short enough. We did not blow southern Idaho to smithereens.

I was disgusted with the situation, shut everything down, and went back upstairs to talk about weight-and-balance. I did take some time to remind Dan how it was important to use all of our senses when approaching an airplane. I heard something wrong. I smelled exhaust fumes. I saw the collapsed nose strut. I felt the kink in the control cable. I tasted the ozone from the failed alternator.

I suppose that there are worse things than radiating in a hangar. Nobody walked by, and nobody got hurt. But, what had happened when the airplane landed? Had one of the line crew marshalled the airplane, and how close did he get to the beam? Was someone hurt? I get weak in the knees thinking about it.

And weaker when I think of how close I had come to hurting someone.

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