Tuesday, March 12, 2013

Putting the Needles on the Lines

I'm thinking of a day I've spent up in the flight levels, technically IFR, because we have to be IFR to fly this high, but my IFR flight plan is so unlike the ones that Air Canada flies that I have to file it with a separate department. I departed IFR from an airport somewhere down there. I think it had an FSS. This flight is not about the origin or destination. It really is about the journey. I'd have to look at the OFP on my lapboard to remember my point of departure, but I'm busy now, so I don't. I like being IFR. There is a greater certainty to what is expected of the pilot, and more security against conflicts with unknown traffic. It's not impossible that there's a rogue Mooney or guy in a lawnchair up here, but it's a lot less likely than in class G airspace, rocketing down some mountain valley at 5500'. ATC has given us a block of airspace to call our own and mostly leaves us alone. Occasionally they vector someone near enough to us that they let us know.

I watch our groundspeed to determine the wind direction and try to get a three-dimensional picture of the weather systems affecting our flight. The wind will back on descent, that is blow from a direction counterclockwise around the compass compared to up here, and it should decrease with decreased altitude as well. The wind affects my turns and will affect my time to get home, where 'home' is an as-yet-unknown hotel in an as-yet-unknown town where we will land. ATC doesn't let me put "TBA" in the destination blank on the flight plan, but I might as well for all the relevance what I did put has to where I'll eventually let rubber touch runway. We have honestly selected a place to land based on a desire for Vietnamese food, although usually our landing criteria are a little more operational than that.

The needles on the analogue fuel gauges are now close enough to the E-markers that I can't see the difference between this and empty, but the fuel flow meter tells me I have how many gallons I have remaining in these tanks. It's about twelve minutes worth, assuming that the fuel is equally distributed between the two tanks, but of course it isn't, because the engines aren't exactly equal and I have leaned each for best economy at this power setting, a fuel flow that changes with altitude and temperature, and probably phase of the moon. Engines are like the economy: a purely manmade thing that we are often at the mercy of. My goal is to switch tanks before there is any decrease in fuel flow caused by fuel starvation, but without leaving anything in the lowest tank. If I wait too long I'll know right away. Pilots call it "blowing a tank." The airplane seems to surge forward on one side, but really it's the airplane lagging on the side where the starved engine has just stopped providing thrust. If I get it exactly right I'll know when I watch the numbers on the fuel truck as they put in slightly more than the placarded useable fuel for this tank. They can get slightly more because "useable fuel" counts only fuel that is available to the engine at all reasonable flight attitudes, and in straight and level flight I can burn some of the fuel that is unusable in climb. When I finally decide that's all the fuel I'm going to get, I put on the electric fuel pumps and move the fuel selector to a set of tanks that are full, fuel except for the tiny amount that I burned in the run-up to make sure there was no malfunction blocking the tank or limiting the movement of the fuel selector. If I couldn't access the fuel in the other tanks I'd have a few minutes of normal flight now before the engines died, and then fifteen or twenty minutes of quiet gliding to find and land at an airport or perhaps a highway.

On this occasion the tank switch works and then we are unexpectedly done work early, so head in to the nearest airport while fuel is no concern. Typically I cancel IFR through 12,500' and complete a VFR approach and landing, but this is a somewhat busy airport with an ILS and there is a lot of traffic, so I hang onto the IFR. I like the extra airspace protection and given the extra fuel I can waste a bit of time. I want to practice flying an ILS. It's a severe clear day and I can hear the controllers being bemused by my request, but they don't try to talk me out of it. I think my request may be a bit annoying for the controllers, but they have more than one runway to play with and I'm sure they'd rather my do this practice now, than have to go missed on a crappy day because my skills weren't up to the task. They vector me around for a long gate. ("Gate" is how far out from the airport you get to intercept the beam that leads you to the runway). In poor weather I get vectored for a really short gate, because I'm slow and light and they want to keep me away from wake turbulence, so this is useful. I get to track the localizer and then descend, tightening up my skills at holding the right glideslope all the way to cleared to land. The needles weren't as close to their respective centreline as that fuel gauge was to the E earlier. That's why we practise.

Taxi off, park and call for fuel. I forgot to record the numbers on how much went into each tank, because I landed with a couple of hours left, so fuel wasn't high on my list of concerns at the end of the flight. Probably only a couple of litres from the shiny dry metal at the bottom of the left outboard. Last flight of the day: secure the aircraft and head to the hotel.


amulbunny's random thoughts said...

We have a 30+ yr old motor home that has multiple tanks. My husband makes a habit of switching tanks during the driving part of a trip because he says it evens things out. He has been distracted more than once and forgotten to switch as slowly we pull off the road to shoot some starter fluid on the carb. There is only one gauge that I can see, most likely because if I saw something near E, I'd get rather mean. Of course this is the guy who ran out of gas on our first date. Guess it's a good thing I don't fly.

30 and whatever said...

As a controller way down there in US airspace who works high as well as really way-down-low traffic all the way into airports, I encourage you to shoot IFR approaches into airports even if its VFR conditions. If my workload is complex it's still important pilots are proficient in instrument approaches, and i'm always happy to give vectors for an ILS if it helps a pilot.

borealone said...

Rogue Mooneys are everywhere!

Traveller said...

I always love the phrase "severe clear".