IFR Training and Partial Panel

Thanks to wrapping up a software release on Friday I got a free extra day off from work on Tuesday. My CFII was available too so this was a perfect opportunity to get back to my IFR training. I’ve been neglecting it lately since I’ve been quite busy and I’ve been keen on doing VFR flying during the spare time I have had. The weather looked ideal for Tuesday and I scheduled two blocks of lesson before and after lunch time.

We started with a quick ground lesson upstairs. After reviewing the standard instrument flying configurations I determined on Sunday we talked about partial panel operations. Out of the standard set of instruments the attitude indicator and directional gyro are powered by vacuum. The turn coordinator is a gyroscopic instrument which is powered by the aircraft’s electrical system. Because of this it is important to practice instrument flying with the attitude indicator and directional gyro “failed” by covering them up. This is called partial panel.

The standard “6 pack” of instruments: Airspeed, attitude, altimeter, turn coordinator, directional gyro, and vertical speed indicator.

There are two ways to master turns in instrument conditions with a partial panel. The easier method is to use the turn coordinator to establish a standard rate turn which is 360 degrees of turn in 2 minutes. To roll out on a particular heading you use the clock (a panel mounted clock is required equipment for IFR flight). For example, to turn 90 degrees left you roll into a left standard rate turn and stop the turn after 30 seconds.

If the clock has also failed the magnetic compass can be used. The magnetic compass has a number of errors which affect it during a turn itself and during accelerated flight. Because the wings are banked during the turn the compass does not read correctly on turns to north or south headings. The Wikipedia article on compass turns includes details of this effect. In normal operations the compass is only used to set and periodically verify the current directional gyro setting but partial panel is all about dealing with failures.

To start the flying portion of the lesson I did an instrument takeoff. In reality it is unlikely that a zero visibility takeoff would be attempted but in this case I donned the hood after lining up at the beginning of runway 32 at Nashua. With my Blockalls instrument training goggles on I increased power and used solely the directional gyro to remain centered down the runway as airspeed increased towards takeoff. From this point on I was under the foggles.

After raising the gear and flaps while in simulator instrument conditions I continued a climb towards the west and Doug (my CFII) gave several different headings to fly and altitudes to climb and descend to. The purpose here was to practice general instrument flight and to verify the pitch and power settings I obtained on Sunday. Generally things went very well. A few times Doug distracted me during a climb or descent and I busted an altitude by a hundred feet or so. But he said I am doing very well for this stage of my training. It was pretty bumpy too!

Next we tuned in the Manchester VOR radio beacon and practiced intercepting and tracking the VOR signal. This went well. I have learned to be more aggressive about my intercept angle and how not to chase the needle. The trick is to use the heading bug on the directional gyro to keep track of what heading I should be flying. Finally with noon approaching I suggested it was a good time to break for lunch and I headed towards Fitchburg and took the finally took foggles off.

The pattern at Fitchburg was busy with another plane which took us a while to spot. Finally we spotted them way ahead of us on short final and continued the downwind. I made a tolerable landing on runway 32 at Fitchburg and we went inside for home made Mac&Cheese and garlic toast lunch at the Fitchburg airport diner.

After lunch it was time for partial panel. This time I did not do an instrument takeoff from Fitchburg but we did look up the standard departure procedure for Fitchburg: “climb via heading 324° to 2600 before proceeding on course.” I did the takeoff without the Blockalls so I could see what the visual view looked like up to 2600 then went back into simulator instrument conditions.

After climbing to 4000 feet and leveling off on a west heading the vacuum instruments were covered with round post-its and we started with timed turns. It turns out that the point I was using as a standard rate turn was actually a bit shallow. Adjusting for my seating position the right indication of a standard rate turn is the miniature airplane on the bottom edge of the hash mark on the turn coordinator. This was confirmed with several standard rate turns to cardinal headings. In each case I managed to keep it together and did a reasonable roll out within 5 or 10 degrees despite not looking at the compass or DG.

Next the clock “failed” and was covered up! Now it was just the mag compass. We did several turns to East, West, North and South headings and sure enough the predicted lead or lag turned out to be quite real and after rolling winds level the compass read the intended heading.

Finally we did a partial panel descent and level off. With no attitude indicator I used the standard power settings and a 500 foot per minute descent on the VSI. Airspeed provided a good check and the turn coordinator was used to keep the wings level. It wasn’t too bad! I was stressed about the partial panel but I handled it well.

Finally, at 3500 feet we did steep turns under the hood. We started with a steep turn in each direction without the foggles then I put them back on and did 45 degree bank steep turns under the hood. Doug said my altitude tolerances were within commercial pilot standards and I managed to keep it together during the steep turns. After one in each direction we headed back to Nashua and I took off the foggles for a visual approach left pattern to runway 32.

The landing was great, very smooth and right on the centerline. I’m obviously getting used to the new runway at Nashua. I have two more simulator instrument hours in the logbook and a lot more confidence. Next lesson will be holding patterns and procedure turns, and maybe an approach or two!

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