Wednesday, January 29, 2014


I’ve come to the conclusion that bosses want their employees to become managers for the same reason parents want their kids to have children. It's not just the obvious reason that they seek to extend their line and influence beyond what they themselves can do in a flat hierarchy. They seek the schadenfreude of seeing the subordinate suffer as the subordinate made them suffer.

Dear former Chief Pilots,
I am truly sorry for any time I needed to be reminded to give you my medical renewal, PPC report, completed exams, or any other bit of paper you have to keep track of. I had no idea of how much of a pain it was.


Thursday, January 23, 2014

Anti-Icing Mythologies

Well-developed ground de-icing/anti-icing mythologies have been developed for the airlines.
         - My misreading of an icing education document

The document said "methodologies" not "mythologies" and that's true for the airlines, but I was anticipating what it was going to say for general aviation. It's not that GA pilots are stupider, just that we aren't supported by the infrastructure the airlines are and we usually have to do our own de-icing. And it always takes place in the stupidly freezing cold, and usually in the dark, because people want their airplane ready to depart at the beginning of the day, but the sun doesn't come up in the winter until it has confirmed that the day is well underway. And even then it only comes up far enough to clock in.

Like the sun, GA pilots' first line of defence against icing is to try to take the winter off. This is actually working pretty well for me these days, especially when combined with our "keep the airplane in a warm hangar" strategy, but when the chips are down I still have to resort to the well-developed mythologies.

Sun will take the ice off, even if the air temperatures are below freezing. In temperatures that are just below freezing, sunlight will warm dark areas enough to melt, or at least soften, the ice on them, and even when it's especially cold the air is dry and the frozen moisture will sublimate into to the air as it warms with the morning. Meanwhile we whack the airplane with brooms or mitten-clad hands to crack the ice and then sweep it to dislodge frost or ice chunks. The official video on not taking off with any ice adhering to your airframe ever recommends sawing a rope back and forth across the surfaces. I've never tried that. Never had a rope. Last year I bought a broom at a northern hardware store, just a regular straw broom, and shared it with a Maule pilot stuck in the same snowfall. When I walked into the office at the end of the trip one of my bosses asked, lightning fast, "What's the broom for? Is that how you got home?" It was too funny to take offense at.

One reason we resort to mythological forces, like windshield antifreeze is that it's available. Most GA airports have no deicing services available at all. Even if de-icing is an advertised service of the FBO on the field, you have to find the phone number and persuade the person who answers to come out and do the work. Let's say you're paid by the hour to do a job that mainly involves driving a fuel truck around and pumping fuel into tanks, plus a bit of sitting in an office and answering the phone. How many hours pay would you want to get up at four am, start a different vehicle that you're not sure is going to work and stand on a ladder spraying poisonous fluids on yourself and some cranky pilot's airplane? If an airport is used by an airline, they may have their own deicers, but generally don't have the staffing, spare fluid, insurance, or billing apparatus to deice other peoples' airplanes. If you happen to be departing shortly after the scheduled airline flight, and have a case of beer handy, you may be able to get a few squirts of the pre-heated deicing fluid from the guys that came out for the flight, but you can't count on that. And you have to know what you're allowed to spray on your airplane and where.

Quick rule of thumb, the odd-numbered ones are okay for me. That is Type I deicing fluid, which looks like thick orange Gatorade, gives virtually no holdover time and can be used on any speed of aircraft is safe and so is Type III. Type III looks like urine, requires a minimum rotation speed of 60 knots, and, if you pay first, has a holdover time sufficient to get you to the runway and airborne in light snow. Holdover time is the time period during which you probably won't get more contamination while standing or taxiing. It's measured from the beginning of the application (i.e. measuring by the area that is treated first). Types II and IV have holdover times sufficient to queue with everyone else on the taxiway at Pearson, but they work by enveloping your aircraft surfaces in cozy ooze, so to use them safely you have to have a rotation speed over 100 knots, to ensure they will shear off before rotation and not interfere with wing performance.

Holdover time is just a mythological luxury for me. In ground icing conditions I need to do everything, including a run up, and then shut down, deice and go right away. That can be a tough call because batteries and starters are not at their best in the cold. If you've got the incantation right to start the engines once in a morning, you don't like to shut down and risk having the magic not work the second time.

Friday, January 17, 2014

Bushels of Icing Certification

An accumulation of ice on the surfaces of an airplane in flight can be ridiculously dangerous, so a lot of science has gone into analyzing the causes and effects. It's known, for example, that large droplets of supercooled water are likely to cause clear icing that covers a large area of the wing, while small droplets are more likely to freeze with entrained air and cause wacky shapes to form around the leading edges of the wing. This is called rime icing. Either way, or both (there's nothing to say you can't get a mixture of both types at once) airplane performance is affected. For starters the airplane will fly more slowly, climb less rapidly, and burn more fuel to get to destination. That alone could kill you, and that's just for starters. This post isn't about the effects of icing, though. This paragraph is just here for people who otherwise wouldn't know why anyone cared about the stuff in the paragraphs coming up.

Some aircraft are certified for operation in known ice, that is to be flown in conditions that are known and expected to cause ice to accrete on aircraft. There's a possibility that definition will cause an argument, because I see that the FAA and NTSB have contradicted themselves a little on this. In Canada there is a much lesser density of PIREPs to airspace and a lot fewer airports of escape, so the conservative definition is the only one that makes sense to me. For flight into known ice, the airframe and the airplane deicing and/or anti-icing systems have to be shown to tolerate conditions conducive to moderate amounts of clear or rime icing. NASA (the first A stands for aeronautics, so not all their research is in outer space) tells me the model for the former is called intermittent maximum and represents "liquid water between 1.1-2.9 g/m3 with drop sizes 15-50 microns in diameter over a 2.6 nm encounter," while the latter model is continuous maximum and represents "liquid water between 0.2-0.8 g/m3 with drop sizes 15-40 microns in diameter over a 17.4 nm encounter."

So first of all: less that three grams of liquid water per cubic metre doesn't seem like very much. A gram of water is a millilitre, about the capacity of the plastic screw cap on a pop bottle. A cubic metre is a fair chunk of space, like the storage capacity of one of those IKEA Expedit room dividers everyone has, the 16-box kind, with two more boxes stacked on top. You wouldn't even notice three millilitres of water in one of those, what with all the scented candles and old copies of Aviation Safety Newsletter stacked inside. I know clouds are stereotypically fluffy and insubstantial, but I would have thought they had a lot more water density than that. So huh, clouds are way drier than I thought.

Secondly, why "over a 2.6 nm/17.4 nm encounter"? At first I assumed that was translated from metric, but 2.6 nm is 4.8152 km and 17.4 nm is 32.2248 km. It turns out that they are 2.99 and 20.0 statute miles, respectively. So three miles and twenty miles. Who the heck does science in grams per cubic metre over statute miles? That's crazier than Canadians measuring our room temperature in celsius and our oven temperatures in Fahrenheit. It's even crazier than having to figure out whether something like pumpkin or peanut butter is a solid or a liquid before converting an American recipe. (Seriously, if the recipe says to use a ten-ounce jar of peanut butter, I never know if I'm supposed to weigh it or measure it volumetrically, because the Americans have the same name for two different units, one for solid things by weight, and one for liquid things by volume. Like the TSA, the recipes expect me to just know what they consider a liquid. Take tuna, for example. I was once told that canned tuna ... I'm getting off topic here. But while I'm here, what the heck is a "stick of butter". Who buys their butter in sticks?) It's even crazier than Aviatrix trying to cook from American recipes.

The certification standards are based on data collection flights performed in the 1940s. If you plot all the possible atmospheric scenarios on a graph with liquid water content on the y-axis and droplet size on the x-axis, the area that is considered safe to operate in is bounded by the x-axis, the y-axis and a curve that approximates a line of negative slope. You may now be asking yourself, does Aviatrix get off on writing sentences like that, or is she just too lazy to draw a graph and show you? The answer is that I get off on knowing that many of my readers can parse that sentence just fine, and I'm too lazy to copy someone else's graph. If there's lots of water you can only tolerate small drops, but if there's not that much water the drops can be bigger. The logical conclusion is that if there's no water at all you are allowed drops of infinite size and that you may fly through a tank completely filled with supercooled water if the drops are infinitely small. That's why I said it was a curve. Presumably the axes are asymptotes. Oh yeah, talk graphing to me, Aviatrix.

One could argue that changes in aircraft design since might have changed the validity of those results, but subsequent work in other types and in wind tunnels should be enough to keep the standard valid. Here's a little bit about how the certification is done these days: flying around seeking out the standard conditions for certification, plus using computer models to determine what shape ice would form on the aircraft, and then sending test pilots out to fly with those globs glued on the plane. I guess when they first did tests to determine what an airplane should be able to handle, they flew through convective cloud for three miles and through stratus for twenty miles and then quantified the conditions they had flown through. They probably did it in ounces per bushel or pop caps per IKEA bookshelf, and it's only been converted to grams per cubic metre for the modern day. Beats me how they determined all that, anyway in the days before the laser equipment they have now.

While trying to find the history of the certification standard I get bogged down in documents on the history of the legal "if supercooled water hangs in the sky and there's no airframe there to accrete it, is it known icing?" debate. This PDF seems like a pretty definitive document about the controversy. Given that many of the people arguing that it's not known icing until they take off and know it's there were doing so as the pilot of record at accident tribunals, I'm sticking to my assessment that if conditions known to produce ice are there, it's known icing.

Sunday, January 12, 2014

My Job is Almost This Cool

Here's a quick look at how beautiful my country is in the winter, and at how obsessed we are with hockey. I get to fly over these same panoramas, and while we don't get to organize alpine lake hockey games, we do choose our restaurants on playoff nights to ensure we can see the games. We can also get the scores from air traffic control if we have to fly during a game. I know of at least one tower that used their local hockey team's name instead of a letter of the phonetic alphabet to designate the ATIS, just to oblige the pilot of the visiting team's jet to say it.

Yes, my job is nearly this cool, and often a lot colder. See them wearing toques in the helicopters? The other day I was wearing a full-on men's parka, complete with the stereotypical fur around the edge of the hood. The fur is removable, but when it's really cold, they haven't made an artificial material that stays soft and doesn't chafe your skin. (Ever notice how much of the really premium stuff is made by animals? Leather, fur, wool, silk, cream, steak, caviar ... I'm surprised there isn't a chocolate beetle).

That lake in the shot is amazing, before there are any skate marks or ice-testing holes on it. Often as we fly over lakes in late fall we're trying to gauge whether they are frozen or not. You see a little bit of white at the edge of the lake and it's difficult to tell if it's ice just beginning to form, or if it's a little bit of snow on the edge of a completely frozen lake. I'm glad it's never been my job to determine if one is safe to land on. Speaking of safety, before you criticize the flight safety involved in a helicopter playing hockey, see the behind-the-scenes planning from this blog entry.

Wednesday, January 08, 2014

Flying Machine

The position of PRM - Person Responsible for Maintenance - is an official one in a Canadian aviation organization. The holder has to write a test and pass an interview to show they understand the regulations and responsibility. There was a while in our company where the holder of the position was trying to transfer the duty and responsibility to someone else because the outgoing PRM was too busy to do the job, but the supposed-to-be trainee PRM didn't hold either a pilot licence or an aviation maintenance licence. That's not a legal problem, but while he was clearly enthusiastic about ensuring the aircraft worked safely, the idea of doing maintenance just because it's legally required was a hard sell. There were clearly a lot of cracks for things to fall in, big holes in those layers of swiss cheese, so I was keeping a close watch, and ended up doing some PRM duties.

The purpose of the above paragraph is to explain why I am the one here talking to the new PRM (neither of the above people) about upcoming maintenance, and why I knew these things. The AME is confused as to why I say the propellers on this airplane will be due for overhaul in the spring, because he knows he just put them on a couple of years ago, and normally propellers have about a ten year overhaul cycle. The AME has previously worked on corporate and private aircraft and, while of course he knows that there is an hours-flown component as well as a calendar time requirement for a propeller overhaul, he can't remember ever seeing anyone fly the hours off before the propeller times out. But we've put almost two thousand hours on these propellers, so we have to overhaul them.

I, on the other hand, have pretty much always worked on commercial aircraft that can easily log twelve hours a day. I'm not sure I've ever seen a propeller time out, except on a plane that we bought for parts. We will send its propellers out for overhaul and swap them onto the airplane whose propellers have timed out.