Little green dots

We went flying on Monday. From the heat of the day there were scattered spots of convective activity popping up all over southwestern Ontario. When you hear convective activity think potential thunderstorms. There was a line of activity north of London running from Stratford all the way to the Hamilton area, and there was also a line developing south down near Chatham as well. When I talked to the weather briefer he mentioned that London and Sarnia were ok for now but thunderstorms could easily start to pop up there as well.

We did our usual flight to Sarnia to fly some ILS approaches, and the weather turned out to be a non-event for us, as there was a wide corridor of clear skies running from Sarnia to London. But we did get to fire up our fancy stormscope which I haven't had a chance to see working yet. For those unfamiliar with such a device, a stormscope measures electrical discharges within a cloud and displays them on a little round display in the form of a green dot relative to the position of the aircraft. How it does this, the best explanation I can give is its magic, but it works. The dots once they've appeared stay on the screen in the same place until the CLEAR button is pushed. They don't move around the display if we make a turn so we have to be sure to push CLEAR everytime we make a heading change, and let the Stormscope start picking up fresh discharges again based on the new relative direction. So if there is convective activity (which produces electrical discharges) within range of our stormscope (25-200 miles depending on the setting) the little green dots on the screen will accumulate enough after a couple minutes that we can make out rather clearly where the good weather is and where the bad weather is in relation to our position. Its really quite fascinating to watch the little green dots start to pile up and clutter the display screen. We could make out very well on the stormscope the squall line over kitchener, and the stormscope also picked up the cell of thunderclouds south near Chatham quite nicely as well. Since it was a clear day we could see the Cumulonimbus clouds building in the distance over Chatham, so we really didn't need a Stormscope to tell us to stay away from there, but the beauty of this instrument is if we were flying in IMC (or even just marginal VFR) and weren't able to see a great distance in front of us, we'd be able to detect any embedded thunderclouds in real time and effectively navigate around the bad spots.

There are two other types of weather detection equipment in common usage. There is the onboard weather radar, which usually has a dome mounted in the nose of an aircraft. This dome picks up the echo's of the radar signal off of any precipitation ahead of the aircraft, and can thus show you where the heavy spots of rain are, thus indicating thunderstorms. These units however are rather large, and expensive, and for the most part are only used on larger aircraft. The other type is also weather radar, but it draws its information from ground based radar stations and relayed to the aircraft by satellite. This is known as XM WX Nexrad Weather. Or just XM Weather. Or just Nexrad Weather. This type for the most part only requires a GPS unit capable of receiving it (with a small current paid subscription), and is thus relatively affordable compared to onboard weather radar, while achieving similiar results. It does have a few minor drawbacks however. Weather information on Nexrad weather is limited to the geographical regions that are covered by a working ground radar station. It is also dependant on a solid GPS signal. It also must be noted that the information given is not in real time. New radar images are transmitted to the GPS units every 15 minutes or so. This means with this system if the weather changes quickly, you'll no longer have an accurate picture, and weather can change very rapidly, especially when we're talking about thunderstorms.

The pros to weather radar of any type is that it is more useful all year round, and it will pick up precipitation of any kind - rain, snow, freezing rain. That is something our Stormscope cannot do. Save from installing a $30,000 onboard weather radar system in our little Twin Comanche - impractical if no impossible - it gives us some pretty good capability. It shows us a clear picture of up-to-the-second dangerous weather in real time, without being dependant on technology outside of the cockpit. Pretty dang cool if you ask me.

May I Never See the Day...

I was browsing through the photos of Twin Comanche's on Airliners.net. My airplane has made it into the photo gallery. Look up C-FINY to find it. But I also came across this photo:

That is a Twin Comanche that seen better days. Every airport has airplines like this sitting around. Airplanes that at one point have had some reason for its owners to abandon it and leave it to rot. In Sarnia there is an old V-tail Bonanza sitting behind one of the buildings in a pile of junk. I've always wondered about it - its history, and what happened to it that made it no longer worth maintaining. Its been sitting there for as long as I can remember, which goes back for at least 15 years. Airplanes like these always seem to be permanent fixtures of the airports. They've sat there for as long as anyone can remember and will most likely continue to sit there and decay for many more years. This one in the picture is missing the nose cowl, as well as the tail cone fairing at the back. Also judging by the way that its sitting on its tail in the grass I would imagine the engines have been stripped off it too. There are also very obvious signs of corrosion. This airplane has been dead for a very long time, and all I can say is may I never see the day my Twin Comanche looks like the one in the picture.

Ahh the Springtime

Ahh the springtime! Warmer days, sun shining, everybody out flying in the clear skies. The sweet smell of avgas, the thrum of aero engines running, nosewheels collapsing... Yes, you read that correctly.

It was gorgeous out today. Warm and Sunny enought that for most the day we just left the hangar door open to enjoy the fresh air and sunlight. Around mid-afternoon I was working away and looked up to see James and Brian (my coworker and my boss) pushing a Cessna 172 into the hangar. Nothing too out of the ordinary, we have lots of planes coming in and out of our hangar all the time. Except something was wrong with the picture I was seeing. The airplane was tilted forward at a very unusual angle. That was because it had some slight nosewheel problems. Ok not so slight. The airplane as it turned out is pretty much a write off. Some student pilot and instructor somehow managed to impact the ground hard enough to push the nosestrut all the way up into the engine compartment. Only about 3/4 of the wheel was left exposed out the bottom of the airplane. The outer 4" of the props were folded back nicely. When we took the top cowl off to look inside, you could see the bottom bracket that braces the nose strut to the belly of the airplane had been ripped off its anchor points and folded up, and part of the firewall was crumpled along with it. The firewall is essentially the core of an airplane. That's what the engine mount is bolted to, and basically the rest of the airplane is run into or back from that point as well. It's pretty much the strongest part of an airplane. The bolts that mount the top part of the nosestrut to the firewall were also all sheared off as the strut was pushed up further into the nose.

Needless to say it was not something you see everyday. I wish I could post some pictures, but I probably shouldn't, as a certain amount of annonymity is probably good at this point. The plane doesn't belong to anybody I know, apparently its from a flight school in the Toronto area. Both student and pilot are ok. I feel bad for the instructor. It will probably be bad news for him, but for all we know there may have been little he could have done. If a student lacks the finess to land properly, and things start to go bad close to the ground, sometimes there's precious little time for the instructor to intervene and regain control of the situation. Then again it could be all the instructor's fault. I didn't see it happen, and I wasn't there, so I can't really comment. It was certainly interesting to see an airplane in that kind of shape coming into our hangar however.

More Hard Work

More instrument practice today. We started off flying a little practice pattern that involved a bunch of instrument procedures, like a procedure turn, deardrop entry, and hold pattern, just to get the hang of flying in that manner. For the most part I had it down fairly easily. Its just a matter of flying a series of timed straight legs and turns as precisely as possible, so Frank decided that he would let me try an NDB approach on for size.

We tuned into the Goderich NDB and made our way north, with me flying heads down on instruments the entire way. We were flying through some light rain showers but for the most part it was relatively clear. I wasn't wearing a hood or foggles or anything, but I wasn't aloud to look outside. Typically you're supposed to wear something that obstructs your vision to everything except the instruments to simulate instrument meteorlogical conditions (IMC), but its really not that hard to resist looking outside as long as you concentrate on the panel.

Actually its so easy to focus on the instruments that I can entirely forget about everything else - that is until Frank makes some off-handed comment about the weather outside or some landmark on the ground, which then I reflexively look up. Doh! As long as Frank keeps quiet though I quickly become lost in my instrument scan: Attitude, heading, altitude, ADF. Attitude, heading, altitude, ADF.

This all comes fairly naturally, its just about reading the instruments and making the necessary corections. The NDB approaches we did today were a different story however. I won't go into the gory details of how its supposed to work and proper procedures, but it is DIFFICULT. Its not nearly as straightforward and intuitive as flying an ILS, but requires a certain amount of spatial thinking - picturing where you are based on the position of the ADF needle versus the aircraft's heading. We flew three approaches and each time I becames so entangled in trying to wrap my mind around what was supposed to happen, and what was actually happening, that I completely forgot that I actually had to fly an airplane at the same time. One attempt I neglected my pre-landing checks, and another time I forgot about descending down to the next step down altitude until it was too late. At that point I was trying to rapidly descend and slow down at the same time before I missed the airport altogether. Descents and reductions in airspeed don't go well together at all. While doing that my attention was diverted from the navigational part of the approach, and I forgot about my final turn after I passed the NDB. I was marginally improving though. By the third one I had the concept of the NDB approach down in my head better. I'm sure when we go up again and get a couple more attempts in I'll have it more solidified in my head. Once I understand completely how its supposed to work, I'll have a fighting chance at actually getting the airplane to do it. I managed to prove today however that if you become too focused on getting one thing to happen right and forget about all the other things you have to worry about things can quickly spiral out of hand.

Today's flight again took so much work to learn and perform what I was being taught, but that is so much fun. I haven't had this kind of fun in an airplane in a long time, its so refreshing.

On a side note, on the way back to london we had a substantial tailwind, and the GPS was showing a groundspeed of 185 kts, or 213 mph. "200 mph club" baby.

Heads Down

I went flying with Frank yesterday. We went down to Sarnia to fly some ILS approaches. It was quite the challenge, and its going to be refreshing to get back into some training that is constantly pushing my limits. Practicing ILS's involves flying the localizer/glideslope down to our decision height, pretending we don't see the airport, then flying the missed approach procedure, back to the NDB, doing a procedure turn to reverse our direction, and then intercepting the localizer and glideslope to try again. That last sentence I'm sure made no sense to any of my readers, and up to a little while ago, it would have made no sense to me either. So I will proceed to decipher what I just said.

The diagram in the top left illustrates the systems we have available to find and align ourselves with the runway. The Non-Directional Beacon, or NDB transmits a low frequency radio wave in all directions that the aircraft's ADF (Automatic Direction Finder) can sense. It actually transmits in the AM band, meaning if we wanted to we could tune to an AM radio station, home in to where they are transmitting from, and at the same time listen to a low budget talk show. The aviation NDB stations however are generally a lot more powerful so they have a greater range, and the only audio they transmit is a series of dots and dashes so we can quickly identify that we have the right station tuned. The ADF indicator in the cockpit has an arrow that will point to the NDB, so all we have to do is follow the arrow to find the NDB station.

The green beam in the diagram illustrates our localizer and glideslope. The localizer will give us horizontal guidance, meaning it will line us up with the runway centerline, where the glideslope will give us vertical guidance, meaning it will help establish us on the correct angle of descent to safely land. The ILS can only sense the localizer signal within 30° either side of centerline. The indicator in the cockpit, shown below on the left, has two needles, that show where we need to be. The horizontal needle gives us glideslope information. If we are below the proper glideslope, the needle will be deflected up, showing us the proper glideslope is above us. Naturally if the needle is deflected down, we are above the proper glideslope, and if the needle is in the center, we are on the glideslope. The localizer needle, the vertical one, works on the same principal. If it is deflected left, we are left of the runway centerline, and visa versa. The indicator shown here is both on the runway centerline, and on the correct glideslope.

Assuming we are in actual IMC (instrument meterological conditions), as in we can't see jack out the windows, and we're flying the ILS down the runway, there has to be a point somewhere that if we still don't see the runway, we have to call it off. That is called our decision height. At Sarnia the decision height for the ILS approach (there are other types of approaches which I'm sure I'll learn eventually) is 200 ft above airport elevation. So as we're descending down along the glideslope, when we reach an altitude of 794 ft ASL (200 ft above the ground), we look up. If we can see the runway in front of us, we land the airplane. If we still can't see anything, we have to execute a missed approach. A missed approach is a procedure to climb out, return to the beacon, and set up for another try. In Sarnia the procedure is a climbing right turn back to the NDB. Now as we're homing back to the NDB, we're going to be traveling in the opposite direction we want to be to set up for another landing attempt. This means we have to do a procedure turn to turn us around. This involves flying away from the NDB on the reciprocal runway heading (rwy 32 at Sarnia is 324°, so we fly a heading of 144°) for 60 seconds, turning left to a heading of 099° for 45 seconds, and then making a 180 back around until we intercept the localizer.

All of this may seem overly complicated and unnecessary when if we have a GPS all we have to is use it to fly where we need to be, but these system of doing things was established long before GPS's existed. Without a GPS, and with no visual reference of where we are, we need some sort of standard practice to ensure that we will be able to find and align ourselves with the runway. Its easy to know where we are when we are looking at a little map with a picture of an airplane on it showing us where we are, but visualizing our position becomes much more difficult when we don't have that birds-eye picture, and we can't see outside. We have to be able to find our way around using only our ADF and ILS.

Understanding how the approach works is one thing, actually being able to fly it is another. Learning to track a localizer and glideslope down to the runway accurately is going to take a little practice. Yesterday I had three attempts. I'm sure on my first attempt if someone was watching us on radar they might have thought I was drunk. I was swinging wildly back and forth across both the localizer centerline, and the glideslope. Its difficult to find the sweet spot that will keep the needles centered - it takes anticipation. We use power to control our glidepath, meaning if we're below the proper glideslope we add power, if we're above, we take some away. It'd be below so I'd add a little bit of power to get back to where I should be, then I'd overshoot the glidepath and be too high, which would require a reduction in power. It took a little bit of practice to learn to anticipate when I needed to reduce or add power to end up stabilizing the descent rate with the needle centered. Each attempt was better then the last. It was some of the most intense flying I've done in a while.

Its really cool to be learning new things and pushing my flying skills into new levels. IFR flying has always seemed like such a daunting thing to me, as it does to many other VFR only pilots. I love the fact that I'm starting to dive into it. It requires so much more precise control of the airplane then VFR flying has ever required, and there's also new concepts, and new things I have to learn. Its so exciting to think about.

Gear Up Now or Later?

I went flying for the first time with my new instructor, Frank. I know Frank from the flight school in Sarnia, but he is now working here in London. It just so happens that I need a freelance instructor to train me for my IFR, and it just so happens that Frank has his IFR and is willing to do that.

It was a beautifully clear day, free of any turbulence whatsoever, and we decided just to do some circuits to give me a break from the intensive engine-out training I have been doing, and to give Frank a chance to familiarize himself with the airplane. Everything went well, but he mentioned something about the retraction of the landing gear on take-off that we had learned differently. The take-off procedure I had been following based on the recommended procedures in the POH and according to what I had been taught were roughly as follows: Rotate at 80 mph, accelerate in ground effect until Vy (112 mph), climb out at Vy, retract gear when there is no longer enough runway to land, set climb power. Frank, who learned in the Seminoles at Empire Aviation, mentioned that I should retract the gear to get cleaned up as soon as we verify a positive rate of climb.

These two different techniques have two different underlying philosophies behind them. The technique I have been using, where we retract the gear as soon as we run out of runway, uses the philosophy that if we have an engine failure, and we still have a chance to get back onto the ground and stop, do it, even if we're already airborne. Once we've retracted the gear then we're committed to going flying. The philosophy behind Frank's technique, is that as soon as we start the climbout, we've committed to being airborne, so we want to ger cleaned up as quickly as possible to minimize the chances of an engine failing while we still have junk hanging out under the airplane.

Thinking about these two different ideas I realize there's pros and cons to both techniques. My technique reduces the chances of us having to successfully fly an entire circuit on only one engine, which historically, has proven difficult for many pilots. The con would be that it requires very good judgement on just exactly how much runway we need to sink back down, land, and stop - especially if we've climbed a fair amount above the runway. That can definitely be difficult. Underestimate the airplane's required distance to stop and we end up in the weeds past the runway. The other technique makes the decision making easier: Positive rate of climb, retract the gear, ok we're going flying no matter what. But it makes the assumption that the pilot will be able to maintain control of the airplane and make it climb in the current conditions. Light twins are notoriously bad in the single engine climb performance. The single engine climb performance of the Seminole at gross weight and sea level is listed as 212 fpm. That is not much to work with. The Twin Comanche is only marginally better at 260 fpm (with only two of us onboard during training I've seen up to 600 fpm). That is assuming proper pilot technique - climb at Vyse (aka Blue Line), with gear and flaps retracted. The second technique also just ignores any runway left over, which in reality isn't the safest action. If you have enough runway its safer to land then to try and climbout, fly the circuit, and return for a landing.

I guess the risk-reward is different too, at least if the engine fails at the initial stages of take-off. The technique I have been taught carries a lower risk, lower reward. If I misjudge the distance needed to land and stop, I may end up over-running the runway. The airplane may be wrecked, but chances are I'll be ok, since we're just rolling off the runway. The other technique carries a higher reward, higher risk. If done properly, the airplane as well as everybody onboard will be just fine, but it may require a higher degree of skill to acomplish. Any mistake, and the results could be ugly.

Of course if we're operating from a shorter runway where there's not much left-over after we become airborne, the two techniques essentially become the same, and there's no argument. With long runways like at London however, I like the technique I have been taught and I think I'll stick with it.