Tuesday, October 11, 2016

Constant airspeed climbs/descents, foggle work, ILS intro, DG trouble

It was so pretty today!  A nice, cool 59-degree start with low humidity, calm winds and clear skies.


TL;DR:  What a good flight!  Be sure to sync the DG with the mag compass before takeoff and recheck it periodically.  The attitude indicator is pretty useful.  The scan is happening, but needs to speed up.  I'm feeling fairly solid on flying by instrument reference.  Maintaining localizer/glide slope is more challenging the closer you get to the airport (or the equipment beaming you the signals).

I got to the airport a few minutes early, finally!  I've been trying to get there ahead of Mark to knock out the bulk of the preflight before he arrives so we can hop in and get to it, but it seems there's always a hold up -- kids' lunches being packed, an extra hug before leaving the house, a forgotten cup of coffee, traffic.  Mark arrived as I was testing the fuel, having completed all else, partially by the iPhone flashlight.  He adjusted the VSI, which has been reading a 100 fpm descent at level (like sitting on the ground) for a while.

The plan was twofold for today:  for me, to get simulated instrument time (e.g., foggle flight) and revisit constant-airspeed climbs and descents, which I haven't done in a decade; and for him, to get in a hold.  I did the radios, which is getting better but still needs work, with today's pointer being to repeat the highest priority information first.  Example:  Tower advised to fly a heading of 130 and that we were cleared for takeoff on runway 17L.  I repeated that info in the order it was given, but the highest priority info is "cleared for takeoff, 17L."  That should have come first, followed by "130."  (130 is a placeholder.)

Here's how the flight looked, taking off to the south, turning east toward the Industry VOR, the hold, and the return:


As we rolled out of the parking space, we checked brakes.  As we turned and taxied to spot 1, we checked that the DG and mag compass were rotating and that the turn coordinator showed a turn (wing dip) and slip (ball displacement).  The attitude indicator always showed wings level.  Super.

I've been using the laminated checklist that's in the plane, but it's lacking.  I have the 172N checklist in ForeFlight Checklist, but this plane is an R and I haven't done the work to get Checklist set up for it.  Quite notable today was the omission of aligning the DG (gyro-powered heading indicator) with the magnetic compass.  Immediately upon takeoff I realized I couldn't use the DG to ensure I was flying runway heading while gaining altitude.  At a safe altitude we went ahead and turned generally easterly toward the IDU VOR and dialed it into nav1.  Once we reached 3000', in straight and level flight, I reset the DG to the compass.

First up was positive exchange of controls while I put on my foggles.  Mark asked a bunch of questions about primary and secondary instruments, which I'd use to assess various aspects of flight, and so forth.  I'm slow and I stumble on this because I know what I look at but am trying to take that moment to think about whether that's the proper thing to look at.  It was only just on this flight that the full utility of the attitude indicator clicked.  Anyway, my big dumb doi moment of this flight is that he asked about bank.  I said I'd first look at the HSI -- I was fumbling in my head for "attitude indicator," got stuck on the word "horizon" (as in, artificial horizon), and HSI starts with H so that could be horizon, right?  No, dumdum.  HSI is the horizontal situation indicator, aka the heading indicator, aka the DG!  I don't think I've ever called the DG by the acronym HSI, but you can rest assured that I'll never call the attitude indicator that again.

Next was a constant airspeed climb.  The aim was 110 kts, and it happened.  I'm not sure why I felt like it was going to be a big deal; maybe because it had been so long since I had done it last.  Pitch up (airspeed decreases), power up (airspeed increases), find the balance ideally around 500 fpm, with max climb rate limited by power availability.  About 50' before the target altitude, pitch back to level (airspeed increases) and let the additional power carry the plane up to altitude, then adjust power for airspeed and level flight.  It went fine, no big deal, yay :)

At one point along our outbound path, the departure controller came on and reminded us to remain VFR at or below 3500', which we were.  That was opportunity #1 to talk about how controllers are looking out for you and for your place within the system.  The class C airspace's outer ring is 2100-4500', and they're maneuvering in this space.  Lil' old 652MA, staying VFR with no particular schedule to keep needs to stay low and out of the way.  Effectively, he was giving us a prompt to check our altitude.

Next Mark did his hold.  We basically went in on the 285 radial of the IDU VOR, and he set up to enter the hold at 26 nm from that waypoint (thanks, GPS!).  At 26 nm, he started the timer and rolled into a right standard-rate turn, which would have us do a 180 in one minute.  At one minute, he rolled out and maintained heading for the next minute.  At two minutes, he rolled right for another standard-rate turn, and at three minutes rolled out for straight and level.  At four minutes, we were just short of the 26 nm mark, suggesting perhaps a bit of a headwind on this heading.

My plane again, and we turned back toward KAUS.  Now it was time for the constant-airspeed descent, which I had my brain around but wish I had taken an extra few seconds to broaden my view and ensure I was ahead of the situation.  We were at 3000' and Mark asked me to descend to 2500'.  I started on it right away but should have paused to process.  500' is not far, and had I recognized that, perhaps the process would have been smoother.  The base problem was that I pitched down too far, then was busy making up for the airspeed increase by managing power and easing pitch and blew right through 2500'.  The descent was complete way faster than it ought to have been, hitting a 1000 fpm descent rate at max!  For a 500' desired change!  Stupid.  Briefly then and more later during our post-flight debrief we talked about always aiming for a 500 fpm change unless conditions dictate or ATC requests otherwise.  It's more comfortable for passengers and keeps change at a rate that's easier to arrest and stay in front of.

As we headed back to the airport, Mark called for the ILS and got the avionics set up.  See what I did there?  I wasn't sure whether he plugged it into the GPS or nav, and didn't notice the toggle button at the top of the panel so couldn't say which receiver was in use.  He called approach and asked for it, they indicated vectors to the ILS and set us on 300.  I turned us there, and after a few minutes of chatting about glide slope intercept and procedure approach asked us to turn twenty degrees right.  Begin opportunity #2 for controller assistance.  A few moments later he instructed us to turn ten more degrees right and say the heading we'd be on, which would be 330.  That was the cue for us to check the DG again.  It had gotten way out of sync again already.  We were in straight and level flight and so dialed in the reading from the mag compass, and then things started looking good.  


The controller brought us fairly far north of the field and turned us to line up with the runway, and it was illustrative to see the glide slope be intercepted from below.  The localizer had come alive before turning in so the task was to try to keep both needles centered.  That got harder the closer we got.  I can't tell you how very tempting it was to just look outside at the runway!  In theory, we wouldn't be able to see the airport at this point, with a minimum decision altitude of roughly 700', when field elevation is 542'!  That means you could break out of the clouds with ~150' and land, or if you can't see the runway at that point you "go missed" and follow the instructions for climbing and turning out.

Mark took over somewhere around 1200' to keep us on the ILS and asked to do the landing.  He taxied us back and I rested :)

What I'm trying to figure out is why the DG got off so badly in flight, after we had already corrected it.  I need to revisit precession (mag compass), think about whether the drift was a symptom of a failing instrument/gyro or vacuum/pitot/static problem, and more.  As for symptoms, the other pitot-static and gyro instruments were behaving as expected, so it seemed isolated to the DG.  And then further, what about partial-panel IFR flying if the HSI (bwahahaha) failed?  That's when I'd really need that magnetic compass behavior to be fresh in my brain!