Friday, November 07, 2014

Geo Referencing

You have at some point probably seen a movie or a television show, usually for children, that uses a gimmick where a story in a book comes to life, or morph into the action of the show. Usually the pages of a book are shown on screen, with text introducing the story, and then a picture. The picture becomes live action, or perhaps the pictures move around in the text. In a movie it's a sufficiently common device that you know if it starts that way, the movie will end back on the printed page with the ornate words The End. But imagine if you were reading a regular, real book. A familiar reference book whose fonts, diagrams, and footnote style have so long been part of your life that you know exactly what to expect of it. Now imagine that a picture or diagram in that book, the one you are holding in your hand, comes to life and starts explaining itself. That's how my introduction to approach plate Geo Referencing went.

An approach plate is a diagram showing an airport runway and the procedures, points and aids associated with navigating an airplane to a point in space from which a safe landing can be performed. If shows the plan view and the side view, with symbols showing where and how to turn, minimum altitudes for each sector and part of the approach, distances, magnetic variation, and type of lighting. It tells you the frequencies for ATC, how much to add to your minimum altitude if using a remote altimeter setting, and has an effective date. The Canada Air Pilot for each region, the physical book in which these things are published is reprinted with changes every 56 days. Most plates don't change from one revision cycle to the next, but the whole CAP is reprinted. When the new one comes you strip the coil bindings off the old one and toss the pages into the recycling. You can tell there's no change if the new plate has the same effective date, worth looking at in case you have inadvertently memorized some data that has changed.

With the Fore Flight electronic flight bag, these approach plates are replicated on the iPad. Instead of paging through the coil-bound CAP trying to guess whether a particular airport will be alphabetized under its own name, or considered a sub-plate of the larger nearby airport, you hold your finger on an airport displayed on the iPad chart until a box comes up, showing all the airports that your stubby finger could reasonably have been aiming at. Tap More next to the one you wanted, then Details then scroll down to Procedures and you can tap Approach and select the approach plate you want. I haven't done a timed test from pulling the iPad or CAP out of the map box, to looking at the desired plate, but I think the iPad is faster. The paper one is easier to read in bright light conditions, even with the iPad turned up full, but in dim light the self-illuminating iPad is great, until it is pitch black dark, at which point it becomes too bright, even if you follow the instructions and turn the brightness to minimum in settings before dimming within the app.

Either way I get the familiar approach plate, very carefully replicated. It's possible to zoom into the iPad ones to read little numbers, easier than pulling out a magnifying glass, but you have to be careful not to leave it zoomed in, when that moment comes on the approach where you glance back at the plate to confirm the minimum descent altitude, and the data isn't on the screen because you zoomed in to see if that waypoint was spelled with an F or a B. A hundred feet above MDA is not a good place to have to pinch or scroll a screen.

The first time I used the iPad for an approach, I had the conventional paper chart and the iPad both out, and it was VMC. I briefed the approach, flew direct the cleared fix and then eeep! the approach plate came to life. A symbolic airplane representing my position appeared on the screen in the position where I actually was. Even though I have used moving maps for years, the appearance of a moving you-are-here dot, Fore Flight calls it "ownship position" on the plate was freaky exciting magic. Ten years from now pilots will stare at old approach plates in puzzlement, unable to situate themselves mentally. This is a huge benefit for situational awareness. It even switches automatically to the taxi diagram and shows me where I am on the airport after landing.

I learned that this was called Geo Referencing a couple of days ago, from an error message. The app told me that Geo Referencing was not available because the plates were not current. What? These are valid until November 13th. (And the error message came up in October). I think American charts are on a 28-day cycle, so the app auto-expired Canadian stuff after that time period. I brought the iPad into the hotel to try and update them. It's just downloading the same set again, I'm sure, but this is hotel internet. It hasn't worked in all the time I've spent writing this blog entry. Why did it not update everything before I left when I selected "pack" for the flight out here? There are a number of things that Fore Flight doesn't get quite right for Canada, and I haven't found a bulletin board or user forum where these things are discussed, to determine for sure whether it is the product and not me who is missing something. I now know that the iPad has to be updated at the same time as I update the GPS database (which comes from the US, on a 28-day cycle).

Tuesday, November 04, 2014

Highway 63

I've been to this airport before. I remember that you can't buy fuel on Sundays, but today is Saturday, and it turns out we've landed at the same time as another pilot who has a key to the pump, so she can fuel any time she likes. When she has filled the tiny tanks on her Cessna single, we stretch the hose out to our tanks and put in fifteen times as much fuel. (The fueller who filled us beside at the FBO next to the solar-powered coke bottles said we had set a record for the amount of avgas she had ever put in one plane. But we were really empty then. I'd gone a couple of minutes into our reserves, because we were working overhead the airport, and there was another one just down the valley, in case of emergency). We go in and pay, and call a cab, which arrives eventually, in the manner of small town cabs on the weekend.

It's an okay hotel, but it's on the edge of town, and the town is spread out enough that it would take about forty-five minutes to walk to a restaurant. And probably as long to get that cab back again, so we order pizza. We try to avoid eating pizza on the road, because eventually we'll be forced to, and we want it to be a treat. We eat the pizza together in my room, while watching a show called "Naked and Alone." It's kind of like Survivor except without the odd psychological games and the uncanny ability of the women to maintain an absence of bodily hair through the whole ordeal. There are actually two people, and they do start out naked, but have made themselves television-acceptable clothing by the time I tune in. They are really miserable: diarrhea from eating too much fruit, driven crazy from insect bites, and one of them doesn't like seafood, but the other one makes him eat it. At the end they get scores out of ten for their survival skills.

In the morning we come down to breakfast, standard motel breakfast of wrapped muffins, fruit, and make-your-own waffles. We ask the clerk if she can call us a cab. There are no cabs here until 9 am. The airport is not actually very far away from the hotel, but we'll be behind schedule if we throw in a half hour walk with our baggage. Back to the breakfast room to chat with the guys in reflective outwear and work boots. They have trucks. I ask them where they work.

"We work on highway 63."

They didn't even know there was an airport around here, but agree to make a small detour to drop us off. I've hitched rides before with a friend of the hotel receptionist, a medevac pilot, someone who just came to drop off her friend at the airport, and the guy who came out to sell us the fuel. It's become just part of the adventure.

Saturday, November 01, 2014

Solar-Powered Coke Bottles

I don't know what these things are. We see them on mountaintops. We saw one at an airport, just outside the perimeter fence, but obviously not installed. We thought it might have come down for maintenance or be waiting for transport to its mountaintop.

They are made of fibreglass. The transparent panes don't seem to be solar panels--I named these things solar-powered coke bottles when we only saw then from afar, and I assumed they were. The thing at the top appears to be a lightning rod, not an antenna. Are there transmitters inside? Are they radio relays? Lightning detectors? A suit of armor for a tree? Are they all over Canada or just in the mountains where we have noticed them?

I expect the full story from a solar-powered coke bottle expert who reads this blog. Don't disappoint me, Internet.

Wednesday, October 29, 2014

Post Mortem

Well what a clusterfailure that was. Imagine if that vacuum and indication failure had all happened over the course of once turbulent flight in night IMC across the mountains. Suction failures are extremely dangerous. The suction-driven instruments are central to the instrument scan and experiments and studies of actual accidents show that they have a very high chance of killing you. The "ninety percent" figure sometimes quoted is misleading: accidents attributed to vacuum failures (about three per year in the US) result in fatalities 90% of the time. That's because there aren't many ways to crash an airplane due to spatial disorientation without it being deadly. More than ten percent of pilots who experience vacuum failure in IMC do get out alive, but I'm not going to guarantee I would be one of the survivors.

Here's what a vacuum failure can look like.

The gyrating blue and black instrument is the attitude indicator. It won't necessarily look that energetic in a failure. Its slide to one side or the other may look exactly like a functional instrument indicating a real wing drop, prompting the pilot to bank and pitch in an attempt to return the aircraft to straight and level flight. The pilot must fly by the turn coordinator, the tippy little white symbolic airplane at bottom left. It indicates rate of turn, not bank angle, so doesn't respond as instantaneously to changes in attitude.

I had difficulty identifying the failed vacuum system because its own indication system did not work properly. When I felt that the heading indicator was not working properly, I suspected the vacuum system, but the indicator lied to me, telling me the system was okay. When I shut down an engine, the associated vacuum failure indication appears immediately, leading me to believe that the same thing would happen in the case of a real suction failure. The two vacuum pumps are in two different engines, had widely separated serial numbers and had been installed by different people at different times. I had never heard of one vacuum pump failing and taking out another one.

If an electric instrument has a power loss, it immediately throws up a flag, so I know not to trust it. There is no failure indicator on the heading indicator or attitude indicator and without other reference, it is really easy to follow the dying instrument. The autopilot tried to follow it, too. With TWO failing vacuum pumps, there was no pressure differential across the shuttle valve to pull the autopilot out of the system. Flying across the mountains to the FBO where company has shipped the replacement pumps, I have post-it notes over the failed instruments, still the only indication, apart from their unresponsiveness, that they are not working. When practicing flying on instruments, if the pilot can see the real horizon, even a little, the task is much easier. Even if you try to ignore it, you subconsciously draw on a lifetime of doing what your species does: visually determining which way up you are. While it's easy to design an indicator that is invisible until electrical power is removed from it, I guess it's harder to calibrate one to not enough suction. Maybe it could depend on gyro rpm. This FAA document claims that "attitude indicators with failure warning flags are available in newer model aircraft and are slowly making their way into the general aviation fleet as retrofits," but I think they may be talking about replacing vacuum-driven AIs with electric ones.

The cause of the double failure is eventually determined to be poorly-installed air-oil separators. Oil was able to enter the dry vacuum pumps and damage the vanes. I'm not sure if the indication issue was because it was a gradual failure, or because oil got in the indicator, too. It is all functional now, but now the vacuum pumps are in phase, which makes me nervous, because that airplane has flown about 900 hours since that happened, and I'm back in it. This article seems to think that vacuum pumps fail every 500 hours or so, but our mandated time between overhaul is definitely 1000 h.

Saturday, October 25, 2014

Are there one or two Ns in "Brokenness"?

I start the engines the next day to do some VFR work. As the engines fire up, the engine start checklist directs my eyes to the tachometer, then the oil pressure, and to the suction gauge. The suction gauge indicates that the right vacuum pump has died. Okay! That sort of explains the zombie heading indicator, and means that I've snagged the wrong instrument. I should have not written it up while it was questionable. The laws don't allow me to write, "never mind, it's not broken after all," which is why there are so many airplanes flying around with sort of broken stuff. As soon as it's written down, it grounds or restricts the airplane. As I understand it, only a maintenance engineer is allowed to correct a pilot's mistaken snags.

Fortunately, the effect of the unserviceability is the same, as I'm not allowed to conduct IFR flights with only one vacuum pump working, and we're in the north in the summer, so "night" is virtually non-existent. What's weird, though, is that the reason there are two vacuum pumps, is that one is supposed to be able to serve as a back up. Either suction pump on its own is supposed to be sufficient to run both the attitude indicator and heading indicator. I'm supposed to be able to safely complete an IFR flight with one suction pump failed. Come to think of it, the autopilot is not supposed to engage if only one vacuum pump is operating, to ensure that there is sufficient suction to run the essential instruments. The autopilot is still working, although a little half-heartedly, as the heading indicator is still sluggish. So is the attitude indicator. The shuttle valve that is supposed to disable the autopilot must have failed, so the autopilot is remaining on line, leaving not enough suction for the heading indicator and attitude indicator. I turn off the autopilot, but it doesn't help much.

After a few hours the heading indicator and attitude indicator are both completely useless. Weirdly, the autopilot will still engage. (I keep forgetting and snapping it on when I want to look something up or open a Clif Bar to eat). But it will attempt to follow the slowly toppling attitude indicator. Pretty scary, really. How far would it roll the airplane? That's not in the manual.

In the old days, there were no heading indicators or attitude indicators or autopilots. The turn and bank instrument and the compass were all you had for staying right side up, and if the former died, it was just the compass, which has all kinds of errors or lag and lead. The old bush pilot trick for letting down through an overcast was to do so on a heading of south. On south, if you bank at all, the compass will immediately swing around, even before the heading has changed, especially at high latitudes. I try this at the end of the flight, because my destination is pretty close to due south of my position. It's pretty hard. Try it sometime.

As I taxi in at the end of the flight the suction gauge indicates that the second vacuum pump has failed. Well this would make a fair amount of sense: the pressure differential between the working and failed vacuum pumps is what is supposed to throw the shuttle valve to disconnect the autopilot. And obviously if they have both failed I can't expect the suction instruments to work properly.

Company has already made arrangements to ship a vacuum pump to a maintenance shop a few hours flight away, so now they will ships two vacuum pumps, and we will head there on the next flight.

Wednesday, October 22, 2014

Death Rates

I'm IFR in the flight levels on a clear VMC day. The IFR part means I'm following a set of rules and procedures ("Instrument Flight Rules") designed for pilots of aircraft in weather conditions that don't allow them to navigate by looking out the window. The flight levels part means I'm flying above about 18,000'. In Canada the "transition altitude," between altitudes designated by the local air pressure and those altitudes designated by a universal standard pressure setting, is 18,000'. One never flies at 18,000', but instead sets the altimeter to 29.92 and flies at flight level 180. I don't know how our transition level was determined. Our highest mountain is about 19,000', so it wasn't set relative to that. VMC is "Visual Meteorological Conditions," that is weather that permits navigation just by looking out the window.

So why am I IFR in VMC? Because in Canada everyone operating in the flight levels is required to do so under an IFR clearance. It's a safety regulation. I have to fly only as directed and cleared by ATC, in order to ensure separation from all other aircraft. And I'm up this high because this is where I need to work. There's only half as much air pressure up here as at sea level, which means only half as much oxygen per breath, so I'm wearing a mask that provides me with supplemental oxygen. The masks do a great job of that. Testing my blood oxygen level always shows me at 98 or 99% saturation, the same level I get sitting on my chesterfield at home. (The tester looks at my blood by shining a light through my fingernail: it doesn't take a blood sample). Only problem is that in providing a tight seal around my face and being secured to my head underneath my headset, the mask give me no opportunity to eat or drink during the flight. Air before food.

The mask also interferes with the seal between my headset earpieces and my ears, so it's a little noisier with the mask on. Even noisier when my noise cancelling cuts out because my headset batteries died. I'm not sure if the noise cancelling "works harder" to keep up, or if it has the same battery consumption regardless of the ambient noise, and this is just coincidence. I use rechargeable batteries, which when they are new last about fifty hours in the airplane before they die, but after many cycles have shorter lives. I have numbered all my rechargeables and track how long each set (the headset takes two AAs) lasts before it dies. When they can't go a full flight, they get retired to a plastic baggie in my kitchen. Eventually they will go to recycling, when I figure out where to recycle rechargeables. They last pretty well: there are only six batteries in the retirement baggie and I've been using rechargeables in my headset and flashlights for at least eight years.

I change batteries and then notice I'm off my heading. The autopilot has disconnected. I must have hit the button. I reset it and then turn to a new heading, but something doesn't look right. The GPS says I'm going where I want to be, but the heading indicator is way off. I reset it to the compass, and it follows for a while, but soon loses interest again. The heading indicator is powered by two engine driven vacuum pumps, one of which I reported close to needing replacement a few days ago. The suction gauge shows slightly less of a vacuum than ideal, but in the green range and no less than it has for a few weeks. The other part of the instrument shows both vacuum pumps on line. The attitude indicator, powered by the same system, still appears to be working. Legally I'm required to inform ATC of the failure of a heading indicator. I do so, and they seem confused. No, it isn't affecting my operation at all. I'm using an electronic guidance system, and I will be landing at an airport that I'll be able to see sixty kilometres away. I don't need it for the flight. Maybe people don't routinely comply with that regulation anymore.

Before I land, the stupid thing comes back to life. Charming. I'm far from base, but I call maintenance so they can order one, or pull one out of another plane or something for when I come back. They don't have any troubleshooting tips for a zombie heading indicator. It's working now, but it's not reliable, so I snag it. That is, I write in the journey log that it is not operating correctly. This will limit our operations to day VFR (the looking out the window counterpart of IFR) only, which is a huge pain in the neck, because it prevents me from continuing the work above FL180, even though its effect on safety is negligible. I have had transient problems with equipment that never recur, but usually they hint at trouble and then throw a full failure if ignored. I think I've only seen simple heading indicators (as opposed to the more expensive and complex HSI) fail twice before in about 7000 hours of flying. And one was a simple fix, turned out that there was an installation error that had made a screw come loose. I wonder if the suction line is leaking or blocked or something. Nothing I can do about it, anyway.

Sunday, October 19, 2014

Peer Pressure

As I fly from one airport to another I speak to numerous air traffic controllers. Let's say I depart Grande Prairie (I think they're almost finished the runway upgrade) for Calgary. I would call Grand Prairie Radio, who would ask me to monitor the clearance delivery frequency. Once I had the clearance I would go back to radio, until after take off, when I would switch to Edmonton Centre. They clear me to my cruise altitude and on course heading, and then might switch me to Edmonton Centre on a different frequency to continue monitoring my flight. As I approach Calgary they will switch me to Calgary Arrivals (which is probably the same frequency as Calgary Departures), who will give me an approach clearance. If there are numerous approaches available at an airport, they may ask me which I prefer. If not, they'll just assign me the usable one. If the weather conditions are fine and I can see the airport, the approach may be "visual" -- no fancy electronics required, just fly to the runway. They can assign me the visual, or I can ask for it, but if I don't feel comfortable with the visual, or just want to practise my skills, I can ask for an instrument approach.

On this occasion I've just switched to the arrivals frequency and I hear the controller telling a pilot, "Everyone is doing visuals, but if that's what you really want to do, you can plan it." That pilot had obviously just asked for an instrument approach.

The pilot responds, "Okay, we'll do the visual."

We did the visual, too, as fast as we could and still get the gear down, because that's what tower (the frequency approach handed me off to) asked for.