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.

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.

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.

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.

Migratory Birds

I learned to use a GPS receiver for air navigation when I was working in the north. Many of the airplanes in the fleet had three line text GPS units. Some had none, but even that nascent technology was so useful, compared to the NDB airways and map-compass-watch navigation they supplemented, that captains spent their own money on handheld units, for the days we were assigned airplanes that lacked the magic box. Airports, radio navigation aids and other named fixes are few and far between in the far north. Given a full load of passengers and cargo and fuel to max gross weight, there wouldn't usually be more than four or five airports within range. It was pretty much guaranteed that when we selected the we selected the "nearest" function, the intended destination would be on the first page. That was the quickest way to select waypoints: no tedious dialing in three- to five-letter identifiers letter-by-letter. Back then we just hit NRST (or rather, I don't remember exactly how, selected it from an obscure user interface), and selected the one we wanted from the list.

Of course this technique doesn't work down south, where there may be hundreds of little municipal and farm airports within an hour's range. Now I'm resigned to dialing in my waypoints, one letter at a time, into the much newer, but still not state of the art GPS unit. But every once in a while the way I learned first re-emerges and I hit the NRST button, to be bewildered by a list of unfamiliar identifiers. Today 'm flying in northern Alberta, not much in the way of towns around here, just a big whack of restricted military airspace. I'm given a reroute via a five-letter fix, still called an "intersection" because once upon a time each was defined by the intersection of two airways. Some still can be located that way, but many are simply convenient lat-long points in space. I always wonder why there are so many of them in close vicinity of LETRM. I think it may have something to do with routing aircraft around the military airspace. Usually they aren't that dense outside the terminal airspace of a busy cluster of airports. Or maybe I just remember better not to do that nearest thing when I'm in an urban area.

Approaching destination I hear the controller talking to a pilot who says he's on a migratory bird tracking flight. I'd never heard of such a thing. The controller says it's great to watch the birds migrating on the radar. Wow, I did not know that either. Birds so thick that they paint primary surveillance radar are a force to be reckoned with. The controller offers to send the pilot a tape, and if I weren't busy getting set up for the approach, I might have asked "me too!"

Here's a composite radar picture of bird migration in the US (see the notes on YouTube for an explanation of what you are looking at). I couldn't find a recording of what it looks like on a local level. How many birds does it take to show up, and can you see the V shape of the skein?

I switched to tower frequency and landed in a challenging crosswind, fighting winds twenty to thirty degrees off the runway and twenty-two knots gusting up to thirty-five, all the way down to the runway. I touch down centred and straight and straight, with one little bounce, but I laugh and point out that they were both smooth landings.

Future So Bright

It's a rainy, miserable fall day with the freezing level a little lower than the minimum en route IFR altitude. I study the GFA showing the cloud levels and types in the area I'll be flying through, and decide that yes, we can do the flight in this airplane. I can climb above the level of the cloud that will carry the most dangerous ice before I reach the area that has those clouds, and destination is clear, giving a safe descent. I file a flight plan beginning with a waypoint that we always file out of this airport, because it's the end of the published departure procedure, but as we're going the other way, I don't expect to actually go there. We'll be in radar contact with ATC as soon as we're off the ground and they will vector us on course.

Except they're busy. I end up flying all the way to the waypoint, and then a little bit past on vectors, and then more vectors. Vectors to the right towards the way I want to go, and then, possibly because I wasn't climbing fast enough for the controller's liking, vectors back to the left. "Vectors" just means the controller assigns me a heading to fly. Altitude is being meted out to me in thousand foot increments, from the departure plate up to the MEA, but still not my filed altitude. We're intermittently in rain, cloud, raining cloud and between clouds. "Raining cloud" isn't a thing that I've ever heard anyone say before, but it's sort of a thing. Sometimes when you're in cloud it's quite light, but you just can't see anything around you. That would be near the top of a cloud with sunlight above. Sometimes it's dark and cold. It's usually very moist, with water running up the windshield, but sometimes it's dark, with obscured vision and pelting rain. I guess on those times I'm inside a cloud underneath another cloud that is raining. It's kind of hard to see, as I'm in a cloud.

I say to my co-worker, "you bring your sunglasses?" He hasn't. "Just wait and see," I tell him. "This is one of the most fun parts of being a pilot."

We're level now, with the outside air temperature flickering between plus and minus zero (it rounds to the nearest degree on the instrument, but must have finer gradations internally). Into another cloud. This one is bumpy, a bad sign, and it's a raining cloud, but water doesn't stream up the windshield. It freezes onto it. All this vectoring around and delayed climb has got me into the area I want to avoid. I can see the water running back on the wings and freezing in little horizontal dribbles, exactly like the icing on the edge of a cake. (I think Americans call that frosting). There's a strip of rime building forward, too. This is not acceptable. Thanks to terrific weather forecasting technology I know exactly where the tops of these clouds are. I tell the controller we are picking up ice and ask for a climb to that level, the level I had wanted to fly in the first place. We get it, breaking through the tops of the clouds, a perspective that changes them instantly from dark monsters that obscure my vision and threaten to burden my airplane enough to tear it from the sky, to a brilliant white reflector for the sun. There's nothing but blue sky overhead, and I quickly put on my sunglasses. The temperature here is below freezing, but the air is dry so the ice sublimates, passes from solid to vapour, leaving me again with a clean airplane after a few minutes.

Approaching destination, ATC advises me that there is opposite direction traffic that could be a conflict, do I want to start down now early, or arrive high? I ask for the early descent and we slip through a few wispy clouds before coming out at our destination, under clear skies. At the end of the day I update the flight time in company records and advise company that there are less than fifty hours left on the right hand vacuum pump. Vacuum pumps have to be replaced every thousand hours. I have often seen them fail early. The possibility of failure is why there are two of them, and I'm pleased that the two on this airplane are out of phase; the left one has only five hundred hours on it.

I Would Have Gone With Stephen Hawking

Before making an approach to an airport, every pilot wants to know the wind strength and direction, what clouds they will encounter, the altimeter setting, and what runway is in use. At some airports the pilot figures out this information herself by flying over the field. At others a flight service specialist simply recites the information to each arriving pilot. At busy airports, a recorded message called ATIS recites the information on a dedicated frequency. The information on the ATIS is typically updated once an hour, or when conditions change. At some airports a controller just reads the information into a recording machine, so you can hear his or her voice, fast or slow, annoyed or cheerful, with occasional minor stumbles and the tower background noise. At others an automated voice reads the ATIS.

Here's a live human reading the ATIS:

Here's the ATIS read by the English-language automated voice Nav Canada uses (in Montréal, the Frech ATIS is on a different frequency):

Today I've just picked up an ATIS that uses an automated voice, and my non-pilot co-worker says, "I like him. He reminds me of David Suzuki." It's pretty obvious that "he" is a robot, and I've never thought of David Suzuki as sounding robotic. For foreigners not familiar with Suzuki, here's a clip. (I ask you to please refrain from commenting here on Malthusian economics, environmental sustainability or Suzuki as a person. The clip is there just so you can hear his voice).

I don't hear the resemblance, except perhaps that he has the earnest careful way of speaking, slowing down to make points. But not more so than any other public speaker. It made me realize, though, that I always assumed the robot was a white guy. I'll try and picture him as different ethnicities now, and wearing different funny hats and ties.

Here's a British automated ATIS voice, not as frightfully British as I was expecting.

People

My eye just fell on a story from a month ago, of a Cirrus that flew into restricted airspace over Washington, DC. Intercepting jets noted that the pilot appeared unconscious, and followed the airplane until it crashed into the sea, I'm presuming because it ran out of fuel. Here's a flight log from FlightAware. The incident itself is not astonishing. The pilot was sixty-seven years old, and while I hope I'm still doing many things safely and well at that age, he wouldn't be the first sixty-seven year old to die suddenly and unexpectedly while in control of a vehicle. The thing that elevates the story to the "I have to blog this" level, was the comments I saw on articles about it.

They aren't vituperative rants blaming the government or the other party (or maybe I haven't read that far yet). They are well-meaning people who have read a news article, digested the information and formed opinions on the material, opinions that they are proud enough of to share. (Okay, that's a low bar: I write this blog, for example). I'm fascinated by the ideas some have, the way they see my world.

The article describes the Cirrus as having an emergency parachute. This is true. It's a safety feature. The Cirrus was designed to attract non-pilots into flying, and one thing many non-pilots wanted was a parachute. A number of pilots have deployed the Cirrus parachute and survived situations they did not believe they would have otherwise. And then you get the comment: Something tells me that a plane built with a parachute for engine failures is not a safe plane to fly. Does this person also believe that cars without seatbelts and roads without guardrails are safer? I've seen this before in comments from non-pilots: adding a layer of safety, be it a procedure, an attitude, or a piece of equipment, is perceived as reducing the safety of the operation. It's as if they assume that any aviation operation has a constant level of safety, so any added safety feature causes it to be lacking in another area.

Another reader asserts, This is a good reason why recreational pilots should be required to have co-pilots. While I don't deny that a second pilot in the cockpit represents a huge safety benefit, requiring recreational pilots to fly with a copilot would pretty much destroy recreational aviation. Most recreational airplanes don't have a lot of useful load, so a pilot would have to leave behind a member of her family or most of the fuel in order to take on a another pilot. Recreational pilots can't be paid for their services, so the pilots would have to negotiate where they were going to go and when, I suppose on the basis of "I'll sit with you when you fly to Montreal, if you'll sit with me while I fly to Halifax." Imagine if you were required to have another qualified driver beside you during every car trip you took. While it must have happened, I cannot think of an accident where a person on the ground was hurt because a private pilot was incapacitated. It's not a sufficient problem to require a legislated solution.

This next one fascinates me because it appears to use the term "nanny state" in a non-pejoritive fashion. Or is my sarcasm detector broken? Google is working on a driver free car, next is the pilot free airplane. I'm not going to see a lot of these advancements, but I sure hope my grandkids don't feel the need to rebel against this cradle to grave nanny state. there are enough mindless thrill seekers out there to fill the emergency rooms right now.

This thread is from an aviation site, so most of the farfetched ideas are corrected and explained by other commenters.

This one is from an American public radio station known to be left leading. Its commenters see a coverup for the plane being shot down, or ISIS action. It makes less sense for ISIS to take down a private pilot on his way from Waukesha, Wisconsin to Manassas, Virginia than it would for them to ambush a suburban soccer mom on the way to the grocery store.

This is from an eyewitness in a boat, quoted in this article. “You could tell the jets were extremely well-equipped and in control of the situation. We obviously paid close attention, but at no time did we think we were in danger. I think the jets could have controlled where and when it went down.” While they could have done that with armaments, the way the Cirrus is described descending into the sea is consistent with running out of fuel and not with being blown out of the sky.

And finally, not to forget that the pilot was a person, I found this blog that compiles the NTSB report, a few news stories, and numerous obituaries. It would appear that Cirrus pilot Ronald Hutchinson was an experienced pilot and well-regarded community member. My condolences to his family and friends.

Female Problems

Don't worry, this post isn't about instrument air filters or the lack thereof. But for the "problems men don't have" category I submit:

Attend aviation conference before work. Bring flight clothes to change into. Forget shoes. Do six hour flight wearing really cute little ankle boots, colour coordinated with your camisole.

Could have been worse. At least I wasn't wearing stiletto heels. I might have punctured the aircraft.