Monday, June 30, 2014

What do beer and thunderstorms have in common?

We all know that beer and flying don't mix. What you may not know is that the same thing that causes trouble for your beer also causes trouble for your flying.

If you're already a weather expert, this post may help you visualize some of the terms you already know in a different way. If you're not, have no fear: you're going to be ahead of the game because you'll understand more about some technical weather terms that you'll see on your private and/or instrument written exams than I did back when I took mine.

Those terms are "convection" and "latent heat of condensation". I made it all the way past my instrument knowledge exam without truly understanding what made convection work. I knew that it was an upward motion of a parcel of air, which was enough to bluff my way though the questions on thunderstorms, but I never could understand why a blob of air would just keep rising until it couldn't rise anymore.

The answer (and, like most things in meteorology, it's a general answer, not a 100% of the time answer) is contained in the concept of "latent heat of condensation". In this case, to keep things simple, let's look as "latent heat" as meaning "stored heat", which might make it easier to see what's happening.

In the spring of 2013, Dale Durran, a professor of atmospheric sciences at the University of Washington, studied how much of an effect the condensation that appears on the side of a beer can has on warming its contents. In this press release, he calculates that a sheen of condensation roughly the thickness of a human hair could warm the beer by 9 °F (5 °C) in only five minutes! That's a whole lot of energy in a small amount of moisture.

To see if those calculations are correct, Durran and his colleague Dargan Frierson performed some experiments, the results of which were published in this not-overly-technical and easily readable paper called Condensation, atmospheric motion, and cold beer. One of the important parts of the paper investigates how much of the heating is due to stored heat of condensation being released and how much is due to heat being transferred from the surrounding air.

They plotted the difference in heat from the surrounding air and that released in the process of condensation and came up with this:

The plot shows that the temperature rise due to latent heating increases dramatically with relative humidity. Moreover, the increase is much larger at 35 °C than at 25 °C, because of the approximately exponential dependence of the water-vapor content of saturated air on temperature. At 35 °C and a relative humidity greater than 60%, the temperature rise due to latent heating exceeds that due to heat transfer from dry air: Latent heating is the dominant factor warming your cold beer.
(Incidentally, this explains why thunderstorms are so rare in the winter: the cold, dense air in wintertime can't hold enough water vapor to store enough heat for them.)

So we've established that beer gets warmed by the release of stored energy as water condenses on the can. What does this have to do with thunderstorms?

Well, consider a cylinder of air that is a mile wide instead of the size of a beer can. Since a beer can is only about 2 1/2 inches wide, this parcel of air is going to be 25,000 times larger, and yet a mile-wide blob of air is not all that big in atmospheric terms. Think of how much stored energy is in that, yet while it's still locked up in water vapor, it's invisible!

Now let's give that cylinder of air a nudge upwards. This nudge could come from encountering a mountain range, or (quite commonly) a lift from a cold front sliding in underneath it and bullying it upward. Once it starts to rise, some of the water vapor will condense as the air cools adiabatically, and a cloud will begin to form. If there is not much moisture (i.e., water vapor) in the air, the cloud might be a small puff or a little layer.

However, given enough moisture (like on humid days), the energy that was stored in that water will be enough to heat that little blob and make it rise even more. As it rises, air from below it will be drawn up to replace it (otherwise there would be a vacuum behind it). The air from below will come up, deposit its moisture as a cloud, and heat itself up. That will make that blob rise, draw up more moist air from below it, and on and on until a towering cumulus (more formally known as cumulus congestus, but you'll usually hear pilots refer to them as "towering cumulus") forms.

This process is what convection is all about, and why pilots are always on the lookout for convective activity. If the atmospheric conditions are unstable enough, that towering cumulus can form into a full cumulonimbus: the dreaded thunderstorm. You can see a dramatic picture of the difference between the two in "Why there is no reason to fly through a thunderstorm in peacetime".


Wednesday, June 25, 2014

SPECIAL PROGRAMMING NOTE!

You've probably noticed that the last two weeks of posts haven't appeared. Is Keyboard & Rudder dead?

Not at all. I've just been extremely busy.

What could possibly keep me so busy I haven't written?

Going to the big new world of the airlines, that's what.

Yes, after several years as a happy flight instructor, a recent change in circumstances has led me to enter the Part 121 scene. It's an exciting new world, with new procedures, new routes, and new equipment to learn (for me, the Dash 8), and that's what I've been up to since early this month.

Once a flight instructor, always a flight instructor, so I'll be writing about the experience of joining a regional airline. For the months of July and August, I'll be posting a week-by-week account of what the process and training is like. My class starts on July 7th, so at the end of that week will be the first post of many to come.

The first week of July's post will be about getting ready for the interview, what it was like, and what I've been doing since getting hired and waiting for class to start. If you're considering a career in the airlines, or just wonder what it's like for the "other half", you should find this upcoming series interesting.

Even if you're not interested in going to an airline, I've always tried to glean the best aspects of all types of flying (military, commercial, and general aviation) to make myself and my students better aviators, so you'll probably find something to make your own flying (or learning to fly) a little better and safer.

Stay tuned for an exciting bundle of posts this summer!

Wednesday, June 11, 2014

The "Fun Curve" of Flying

One of the ways learning to fly changes your life is that it presents you with challenges that you can either face up to or run away from. Dealing with these teaches you about who you are and makes you better at dealing with life's obstacles.

One of these challenges is dealing with learning how to press on even when things aren't as fun. Life itself is a series of ups and downs with its good times and its bad times, and flying is just life on a smaller scale.

Unlike life, however, I have a map for you that will tell you when the good times will be and when the not-so-good times will come. I call it the "Fun Curve":

Click image to embiggen.
It is divided into five stages, with an angry red box in the middle where pilots are made and sorted out from regular people. These stages are:

1. New maneuvers: Everything is brand new and it is amazing. You have no idea what you're doing, but who cares? Just being in the air is as fun as can be, and there's plenty of time to get good at all this stuff later!

2. Pre-solo: There's the first sharp dip in the Fun Curve. You're testing out 50 different ways not to land an airplane, and halfway through you start to wonder if you'll ever get it right. That's when you enter the red box. Those with persistence will be rewarded with even less fun, as flying around in circles around the pattern time after time after time gets wearisome. Just as it gets so close to the bottom as to try even a saint's patience, you get that first solo and things are way more fun again! Those without persistence drop out before that unforgettable day.

3. Post-solo / Cross-country: You've shown you can fly all by yourself, and now you can go out into the practice area and practice what you want, when you want, for as long as you want, without some constant chattering in your ear coming from the right seat. After that, cross country flights take a lot of planning, but they're fun because you're going places you've never been. That's great until it's time for...

4. Checkride preparation: The second sharp dip in the Fun Curve, and the second most common place where non-pilots fall by the wayside. You've spent all that time practicing on your own, thinking you were doing pretty well, and now the right seat is filled with an irritating yipping instructor again. You do the same things over and over again—again. When you're not flying, you're studying for the oral portion. When you're not studying for the oral, you're wondering if you'll pass the flight portion. If you stick with it, eventually you end up getting that second big instructor signoff: the practical test endorsement. You pass and end up as a...

5. Licensed pilot: This is where the one line splits into two.

The green line represents those who continue to learn and master the art of flying. With most things in life, the better you are at something, the more you enjoy it. The more you enjoy it, the better you get at it, so this line goes slowly but steadily upward.

The red line represents those who (in what is an unfortunately common trajectory) stop improving their skills after they pass. Eventually they've seen all their buddies' houses from the air and eaten all the $100 hamburgers they wanted. After that, flying gets dull for them, and they often stop flying altogether.

For the second group, there are two pieces of good news. First, it's often possible to become one of the green liners by deciding to pursue an instrument rating or a tailwheel endorsement or a seaplane rating or doing any of dozens of things that bring the spark of newness back into flying. Second, even if you do drop out for years, after you have your license it's good forever. All you have to do is get with an instructor, brush off the rust, and get back in the air.


The two main things to take from this curve are:

First, if you're at a point in your training that you're starting to doubt whether you'll ever make it (or perhaps you've already dropped out because you thought you where the only one to ever have trouble learning to land an airplane), you can see that you're going through the same thing the other 600,000+ pilots in the United States went through, too. If they could make it, then so can you.

Second, you can see that the curve shoots up sharply after the low points. That's my way of saying, "It may suck right now, but once you get through it, it's fun again. Trust me."

Just like anything involving human behavior and psychology, this curve will not be identical for everyone. However, I've seen this pattern so many times in so many students that it probably won't be too far off for you. If you'd like to share your own experience, leave a comment below.

Friday, June 6, 2014

Bringing you what brings the weather

I recently had a chance to visit the National Weather Service office in Cleveland as part of a Northeast Ohio Chapter of the American Meteorological Society event. While the weather happens up above, the people at the NWS are the ones who bring it to you.

Whether you're planning a flight or a picnic, or want to know if you need to go shopping for a new pair of ruby slippers, the forecast you need comes from a two-story building on the west side of the field at Cleveland-Hopkins. The Doppler radar you're used to watching on the TV or on the Internet is right in the parking lot:

The CLE Doppler site. Note the NASA hangar in the background.
This system is what controls it:


Did you ever wonder how that annoying screechy tone and bad weather news gets to your television? Through these stations, that's how:


In the event of severe weather, the staff goes over to one of these units, pushes some buttons indicating what kind and where, and it's on the air.

Close-up of the rack above the monitors. (Click image to embiggen if you want to read the labels.) Still looking for the button that says "Global Thermonuclear War" on it.
I don't think any of these six monitors let you zoom in to see if your long-lost wife is working in the garden, but they do let the forecasters see a bunch of weather data at once:

If that looks like the WKYC Doppler 3 radar image at the upper left, that's because it is. Apparently the radar goes from the dome in the parking lot to Channel 3's office downtown, then gets piped back to the NWS office where it came from in the first place.
One of the more interesting things to happen while I was there took place at this desk:

The windows have a nice view of the airport.

There was a staffer in the chair and I was talking to another one while standing behind it. I mentioned that I keep the TAF site for Cleveland and Mansfield bookmarked on my phone so I can check it easily throughout the day. I asked if this is where they come from and he said, "Sure. Kirk here just put the last one out a few minutes ago."

So I got to meet the guy who writes the crazy TAFs I've written about, and he even spent a while showing me how they get made. I always wondered if they have a mini-model or some sort of local forecasting aid that does most of the work like the continent-wide models do. As it turns out, when it comes to TAFs, it's still plain old looking at the maps and using the brain to figure out what's going to happen—much like a pilot's typical preflight weather planning, but with professional tools. (One of the tools he introduced me to is Bufkit, which is great if you like Skew-T diagrams.)

Many of the places you use as a pilot or as a taxpayer are available to check out. Go see what else is out there for you to explore!

Saturday, May 31, 2014

A successful failure


This month, the FAA launched an initiative called "Got Weather?" to help pilots get better at evaluating weather and its hazards on their own. Each month has a separate topic, and May's is turbulence.

It's no secret that weather is one of my favorite things about aviation, so to contribute to their initiative, I'm capping off my May schedule of posts with a little story that blends turbulence, equipment failures, a failed forecast, and a failed landing attempt into an extremely successful flight.

It was a dark and stormy night.... Well, actually, it was a clear blue day. Slightly on the breezy side, but not horribly so. The winds were a steady 14 knots, about 70 degrees off the runway. A little outside the comfort zone for the person I was flying with, but sometimes you have to get outside of that nice comfy spot to expand your skills. The key is to get out of that comfort zone safely, and since 14 knots is both within the 172's maximum demonstrated crosswind component and my own proficiency and currency envelope since I fly this particular aircraft several times a week, this instructional flight should be a... breeze.

One of the flights I always have my students do is a trip from Lorain County to Carroll County to Burke-Lakefront and back to Lorain County. This is a busy flight, since it hits Class B, C, and D all in one shot. (Because there's so much going on in it, it is the basis for one part of the final project my AVIA 111 students do, too.) People who learn to fly with me don't get to duck under airspace or shy away from talking to controllers. Once you get used to talking to them, you'll quickly learn that they are one of your best resources. Use everything in the cockpit, and the radio is in the cockpit, right? The reward is that once you make it to Carroll County, you can eat the best pie in the state of Ohio.

From SkyVector.com


So, the plan for what we're going to do is done. The preflight is done. One part of the preflight preparation was the TAF, which was calling for winds lighter than the actual ones. They were supposed to be 10 knots, increasing to 15G25 right around the time we would be returning. That's something to make a note of, because that often means that the weather is going to end up worse than forecast. But that was just an opportunity for a nice crosswind takeoff.

One of the first parts of the plan was to contact Cleveland Approach and get cleared through their Class B. The frequency was already in standby before takeoff, so a simple switchover and callout was all that was necessary. It went like any other, until the controller couldn't make radar contact. We reset the transponder and tried again. No luck. It looked like either our transponder was dead or his system was having issues. We finally agreed to just stay under his Class B shelf and continue on course.

Once we started getting close to Akron-Canton's airspace, we tried again. This time it was the same failure to make radar contact, except that the controller said that he was getting a transponder code of 7777 instead of what he had assigned us. (That's really bad because only the military guys get to use that squawk code.) Again we reset the transponder and again it didn't work. Now the problem was definitely with us. We agreed to circumnavigate his Class C and continue on our way.

While we were working with Akron-Canton Approach, we started getting some bumps. There were no airmets for turbulence along our route, although there was one well to the east of where we would be. There were also no pireps of turbulence in the entire state of Ohio; the only scattered ones were in the area that had moderate turbulence forecast, and those reports were 1 light, 2 light-moderate, and 1 moderate. (I only include those pireps from about 10,000 or below, since our 172 won't make it into the flight levels without being strapped to an SSME.)

Naturally, neither forecasts nor pireps are solid-gold indicators of the absence of turbulence. Pireps are especially non-reflective, since they're only given by those who know how (which is actually pretty simple: just tell ATC you want to give a pirep and then say what it's like up there), aren't too lazy to, and aren't too busy fighting to keep the shiny side up in turbulence.

This, unfortunately, was one of those times when no news was not good news. The closer we got to the destination, the worse the bumps got. By 10 miles out, there were a few that definitely would have made a good moderate turbulence pirep for ATC. I have a rather high tolerance for getting bumped around a cockpit, so when even I'm starting to get a little irritated, it's at least moderate.

Now comes the time when a lot of metal gets bent: at the end of a cross country flight, so close to the airport that it calls to you like a Homeric Siren. The AWOS was reporting winds 80 degrees off the runway at 21 knots gusting to 27. You have the airport in sight. What do you do?

Discretion is the better part of valor. The wise pilot knows when to say when. These conditions were pushing up against my own skill level. I let him fly the pattern and try to land, with my hand right by the yoke ready to jump in if necessary, as I fully expected us to not even be able to touch asphalt.

We managed, after an approach that wouldn't win any trophies for precision, to land. Many times, the natural instinct after feeling wheels touch pavement in conditions like that, is to breathe a sigh of relief and be glad it's over. However, especially in a crosswind, the landing isn't over until the plane is in a hangar. As soon as the upwind aileron was released, the wind got under the wing and raised the plane up a bit on that side, pushing it toward the side of the runway.

It's never too late to go around, so power up, pitch up, clean up, and speak up. That's what we did and decided to skip the next leg and head for home instead, where it was a little saner—or at least it was when we took off. There wasn't even a thought of going back in the pattern and making a second chance at a landing.

On the way back, we were getting beat up again, so we used the time to see how well the wing leveler on the autopilot works. Use all the resources in the cockpit, which includes the autopilot when necessary. It did a passable job keeping the shiny side up until we got back to the home patch.

Back home, the winds had picked up to 17 gusting to 24 and at a right angle to the runway. However, this pattern and approach went much more smoothly, and the landing was a very nice one without me even touching the controls. As we taxied back to the hangar, I thought about the sentiment that Ernie Gann and Bob Buck expressed about how sometimes 1 hour of time in the cockpit is worth 100 hours in a logbook. This was one of those flights.

Why? How could I be so pleased after coming home with an empty belly?

Look at all the things experienced on just one flight:

  • A real (not simulated) equipment failure and working with ATC about it
  • A real (not simulated) in-flight change of plans because of it
  • A first encounter with real turbulence
  • An approach that shows why it's better to bug out than bend metal
  • Why textbooks (and instructors) say to keep that aileron down all the way through rollout. It's no longer just ink on a page but a real experience.
  • A real (not simulated) go around in tough conditions
  • A real (not simulated) decision to abandon the original goal
  • A real (not simulated) diversion because of that decision
  • A real (not simulated) need to use the  autopilot to reduce workload. Autopilots are excellent tools if you use them as a workload reducer, not a brain replacer
  •  A confidence-building nice crosswind landing back at the home drome—and the yoke stayed fully deflected the whole time after that learning experience at Carroll County
If every flight "failed" this successfully, we'd all be aces in no time.

Got a "So there I was..." story? Leave a comment and share it.

Saturday, May 24, 2014

It's Discover Aviation Days 2014 time!

Every year in May, Lorain County Regional Airport plays host to Discover Aviation Days. Every year, it gets bigger, and this year is no exception.

In four years, it has grown from a small static display of a few aircraft for a few hours on Saturday to an all-weekend affair with large exhibits, Young Eagles flights, B-25 bomber rides, and an actual airshow with professional performers on both days, plus a night airshow starting at dusk on Saturday. There's even camping for those who want to stay both days.

Discover Aviation Days is organized by the Discover Aviation Center, led by the improbably-energetic Paul Koziol. With some help, in November he also created the Discover Aviation Center Flying Club, of which I am Secretary. As part of my communications role, I've finally managed to roll out the first issue of the club's newsletter, which you can read here.

Want to see how much it's grown in just three years? Check out the picture from 2011 on page 9!

Monday, May 19, 2014

What happens to hopelessly lost luggage?

It's extremely rare that I devote a post to someone else's material. After all, one of the big reasons I devote much of my time to writing Keyboard & Rudder is to bring you my own personal, peculiar take on learning to fly in a fun, offbeat way. Instead of simply rehashing the same old, dry, academic topics in the same old, dry, academic ways you can find a hundred places elsewhere, I try to cover either something you won't find anywhere else (like extraterrestrial airports) or to cover a topic in a way no one else does (like actually admitting when I make a mistake so we can learn from it).

Dan Lewis has had an outstanding newsletter called Now I Know for quite some time. (In fact, I linked to one of his stories in #10 of my post "Ten for 110: Ten things you might not know about the Wright Brothers".) Although it's not an aviation newsletter, he covers an offbeat range of things in an engaging way. Occasionally, the odd and the overhead line up, as in "Where the Bags Go," an extremely interesting post on what happens to luggage that gets hopelessly lost.

While you're there reading that, you can sign up for his free newsletter to get more like that in your inbox. (You'll probably want to!) In fact, his newsletter is so good that he's turned it into a book, which is where the article originally comes from:


 

(If you use that link to buy it, you help support this site with a small commission at no cost to you, you help support his newsletter with a sale, and you get a fascinating book... everybody wins!)