Flying Training

Lesson 31: Basic Instrument Flight 1

Saturday 22 July 2006, 9.30am with Kerry Scott in Warrior VH-PBS

Weather: overcast, rain showers, sunny patches up north

Instrument training at the PPL stage is extremely basic. The purpose is firstly to demonstrate to the student that without a visual reference you cannot reliably determine aircraft attitude, and secondly to give the VFR pilot the basic skills needed to get safely out of cloud if you find yourself in it. The emphasis is on 'Basic'. A full instrument rating is another 40 hours of instruction.

Curtis uses the Warrior not only because of its full set of instruments but because the side by side seating enables the instructor to do critical things like see whether the student is peeking under the hood, and to stick yellow labels over instruments to remove them from view.

My preparation for this lesson included reading the relevant chapter in David Robson's Flying Training Manual (twice) and Kerry's own briefing notes on instrument flight. I also downloaded a Piper Archer (similar to the Warrior) add-on to Flight Simulator 2004 and took it for a few flights, first normal circuits, then some in thick fog. Still on the simulator, I filed and followed a couple of IFR flight plans, and practiced recovery from some unusual attitudes. Cameron decided to give me a challenge so he insisted I fly up to 4000 feet, still in cloud, then he fully leaned the mixture and had me do a glide descent on instruments followed by a forced landing in the fog. I nearly made the runway too...

I was up at 6.30am and at Camden before 8.30, to give myself plenty of time to familiarise myself with the Warrior. I discussed its flying characteristics with a couple of other students, did the preflight, and listened while Kerry explained the finer points. For example, the pitot and static vents are on the same inconspicuous little fin under the port wing. And the fuel tanks may not read correctly if the starboard oleo leg has been compressed by some heavy pilot standing on the right wing, so Kerry actually gets under the wing and pushes it back to a wings level attitude before taking the reading.

Other new preflight checks included the oleo extension (mains and nosewheel), anti-collision beacon (no strobes), and in the cockpit, the annunciator panel (ie warning lights), fuel selector (set lowest tank) and fuel gauges (which are electric, so check with the master switch on).

The engine is the same as the Citabria, a 160 hp Lycoming, and starting procedure is similar. We applied the parking brake first. (Lift up the lever and depress the button. To release, lift up the lever; the button will click off and the lever can then be lowered.) Trim is checked by rotating the wheel until the wire indicator is lined up with a white painted mark on the trim housing. Fuel selector is set to the lowest tank, and electric fuel pump on, then the key is turned to start it. It was reluctant at first until Kerry retarded the throttle slightly, then it fired up.

Throttle is set to 1200 rpm for a hot start, oil pressure checked and electric fuel pump off, then the instruments are checked. This includes a check that the suction is working (extreme right of panel) and the gyros are starting to erect themselves. Then it was radio on, check the ATIS, runway in use (06), set QNH, parking brake off and taxi to the run-up bay.

The run-up and pre-take-off checks are also similar to the Citabria, with some additions. Specifically, throttle to 1200 rpm, fuel selector to the fullest tank, electric fuel pump on and check fuel pressure. I called the tower for take-off clearance and received the instruction to make a rolling take-off. This means don't hang about as there's someone on final, which added a little extra stress because I was still unfamiliar with the whole different flying position compared to the Citabria. You hold the yoke in the left hand and the throttle in the thumb and forefinger of the right hand, other fingers on the throttle quadrant to enable fine control of the throttle setting. Also the rudder pedals feel different - your feet are closer together and the brakes are clearly separate above the pedals (no bad thing).

On the takeoff run the yoke is held back to relieve load on the nosewheel (but not too far back!) and the acceleration was definitely more sedate than the Citabria. Kerry told me to hold it on the ground until it reached 70 knots, then we lifted off gently, trimmed for best rate of climb at 76 knots and departed upwind for the training area.

For the rest of the flight I didn't see too much of the outside world because Kerry produced a semi-cylindrical grey plastic hood which is held over the student's head via an elastic strap and effectively blots out all view of the outside world (unless you happen to be looking up at the compass).

Kerry first covered up the bank indicator at the top of the Attitude Indicator (so the student uses the turn co-ordinator to set the bank angle) and then the Directional Gyro, Altimeter and Vertical Speed Indicator. She then asked me to keep it straight and level on the AI. After some initial overcorrections this didn't prove too difficult, and Kerry reintroduced the other instruments. Before long I was making co-ordinated rate 1 turns onto specified headings, without gaining or losing height. The aim was to have me set an attitude while looking solely at the AI, then confirm that it was correct with a quick glance at the performance instruments. These lag behind the AI, so it's back to CCHAT - Change, Check, Hold, Adjust, Trim (for climb and descent). As per the manual and briefing notes, I found it was critical not to fixate on one instrument. So for a turn you set an attitude (banked and level) on the AI, then look down and left to the turn co-ordinator (check rate one), back to AI (adjust if necessary), down to DI (check progress towards the new heading), back to AI, over to altimeter (check height), AI, VSI (not climbing or descending), AI etc.

After a few turns Kerry had me climb and descend to specified heights, with appropriate checks, throttle settings, carby heat and trim. With less distractions from outside it was actually easier to remember PAST - Power, Attitude, Speed, Trim when entering a climb or descent, and when levelling out after a decent, and APST (attitude to level flight and let the speed build up before throttling back) when levelling out after a climb.

Next came climbing and descending turns. This involved a scan of all the intruments, with the VSI being important to confirm the desired 500 feet/minute climb/descent rate.

Then it was time for a demonstration of how untrustworthy the body's non-visual senses are. Kerry had me close my eyes, take my hand off the yoke and feet off the pedals, and tell her what the aircraft was doing. I thought I detected a turn to the right, then after a while it seemed that it was definitely a right climbing turn, so I said so. Kerry replied, "Open your eyes."

We were making a level turn to the left.

I suspect that Kerry may have started with a turn to the right, then perhaps increased rpm slightly and made a coordinated turn to the left before removing a little bit of rudder to allow the aircraft to skid out of the turn. The slight acceleration from the increased rpm would have pushed me slightly back in the seat, giving the impression of being nose-up, and the skid would have pushed me left in the seat, giving the impression of a turn to the right. Whether my interpretation is exactly right or not, this was a good demonstration of why you have to trust your instruments in IFR.

Note that with your eyes closed, a gentle, perfectly balanced turn would be indistinguishable from straight and level flight, because the combined effects of gravity and the bank would mean your weight was still acting straight through your CG to your feet. In fact I've seen a video of Bob Hoover rolling his Aero Commander through 360° with a glass of water standing on the dashboard, and the surface of the water did not move relative to the glass. If a glass of water doesn't notice the aircraft rolling, neither would a blindfolded passenger.

Now that I was comfortable with using all the flight instruments, Kerry started covering them up again! Neither RRW nor MWY have AI nor DI (both driven by suction), so this was to simulate being in cloud in either of these Citabrias (or any other aircraft with basic instruments only). The turn co-ordinator suddenly becomes very important as it's your only guide as to whether you're flying straight, and the altimeter and VSI are your guides as to whether you're level.

Now Kerry asked me to watch the compass (I could finally see outside! Hmmm...rain showers) while she first accelerated the aircraft, then decelerated. While accelerating, the compass card started drifting towards south, and while decelerating it drifted north. There's an acronym to remember this effect - SAND - South Acceleration North Deceleration - but I guess the main point is don't try to set a heading unless your speed is steady.

Probably more important is the tendency of the compass to overread when turning north, and underread when turning south. The acronym for this is ONUS. So if you're turning north onto a new heading using a magnetic compass (the effect does not apply to the DI), you should aim to rollout say 15° past the new heading, then wait for the compass to settle into its new position before making any fine adjustments. Conversely, when turning south you would roll out 15° before the new heading. Kerry had me turn due north and due south to practice allowing for this effect.

The last part of today's lesson was to recover from unusual attitudes using instruments. So Kerry had me close my eyes again and take my hands and feet off the controls, then she put the aircraft through a few manouevres, no doubt gentle compared to the aerobatics in the Citabria, but quite disorientating when you can't see which way the horizon is headed. Then she had me open my eyes and fix the situation. To do this your eyes have to shoot straight to the AI and make a snap judgement of the aircraft attitude. You then take instant action on the controls to restore straight and level flight, before checking on the AI and performance instruments that your actions are correct. I recovered from nose-high and nose-low banked attitudes and Kerry seemed quite satisfied with the speed and appropriateness of my response.

Kerry had me fly back to Camden still on instruments (including a determined attempt to fly through the middle of a rainbow) before I was allowed to remove the hood. We were now on final for runway 06 and the only remaining task was to get the aircraft back on the ground smoothly. I did not manage this without significant control input from Kerry, which makes me think that I need a fair bit more time on the Warrior before I could be trusted to fly it solo. It's obviously got more inertia than the Citabria, which means noticeable control lag, so you have to think ahead. Combine this with the left hand having to make fine pitch corrections and it makes for a very different experience.

I should mention that in the BUMFISH pre-landing checks for the Warrior the 'F' for fuel includes setting the fuel selector to the fullest tank, switching on the electric fuel pump and checking the fuel pressure is in the green. The fuel pump is switched off again while taxiing back to the parking spot.

Click to enlarge Kerry's comment on my performance was 'satisfactory', so the preparation paid off. Having completed all the paperwork (aircraft type is PA28 in the pilot's logbook) I grabbed a roll and was contemplating departing when Kerry popped her head back into the office and said Steve, her next student, had offered me a place on his nav to Cessnock and return via the coast and Sydney Harbour. Luckily I had no family commitments (highly unusual) so I accepted with alacrity. This is a separate story, which I'll write soon with the help of my notes at the time, and the 91 photos I took, one of which is on the right.