VOR holds and approaches

I have now had six sessions in the DA-42 simulator, three days of groundschool and the first IFR flight in a Cessna 172. It feels like quite a step up from the VFR Katana flying of only a few weeks ago!

CTC's IFR aircraft are all fitted with the Garmin G1000 system which allows consistency across the simulator, single-engine and multi-engine parts of the IFR training. The G1000 screen presents its information in a very similar way to the glass cockpit displays of the average Boeing or Airbus aircraft. Crucial to this is the Artifical Horizon (AH) and its surrounding information - the airspeed, the altitude, the vertical speed, the angle of bank and the heading. All this information is spread across many instruments in a conventional analogue aircraft but is presented in an easy to read display in the G1000 system. A word of caution though: the accuracy of the information can lead to distraction. Chasing 120 knots airspeed from an indicated 118 or 6980 feet that should read 7000 can lead to one's attention being taken away from other important information. In an aircraft with dials/gauges that level of accuracy is so hard to determine that it is unlikely to be distracting. However, with an effective scan being maintained it is possible to avoid the temptation of fixing on one item.

Our simulator sessions have really focused on the use of the Horizontal Situation Indicator (HSI). This is a compass rose that orientates itself with the heading you are following at the time at the top (347 in example below). Within the rose are displayed two pointers usually, one outer one that points itself towards the beacon you are tuned in to (VOR, NDB or GPS waypoint) and the inner one that you point yourself towards a selected course. 

A G1000 screenshot showing the GPS pointer activated in purple on the HSI

So to give an example, the final track to land at Hamilton airport on runway 18L is 176 degrees. So the inner pointer (green for VOR) is set at this. The pilot then makes sure that the outer (blue) pointer aligns with this. Sounds easy enough but there are many situations where the two pointers do not align deliberately and it is the relationship between the two that is relevant. Then we add in wind! Never do you fly an aircraft in completely still wind conditions. There is always some slight disagreement between where you want to go and where the wind is making you go. Therefore compensating for this and heading in a direction that will bring you on to the desired track is crucial in achieving accurate instrument flying.

For example, the above example of a 176 final approach track at Hamilton might be affected by a wind from the west. As winds tend to become less strong and gradually change direction as you descend, the heading required to track 176 (eg. 184) at 4000' could be very different to that at 1000', depending on the strength of the wind. None of it is an exact science as we can only make an educated guess at the wind strength and direction* - consequently there are small tolerances built in to the tracks and altitudes of the published procedures to accommodate the minor inaccuracies in prediction and indeed variability of the wind.

Our next few Cessna flights consolidate these procedures and add in various en route elements gradually to build up to the stage of full IFR route practice. After that we get the first taste of flying the Twinstar back under VFR in order to get used to the handling characteristics of the aircraft before flying it in more IFR procedures. Sorry this is all very wordy but it is all very procedural at the moment, albeit very interesting to do. Lots of flights coming up and ideally some decent weather so I hope to get some good pics for the next update!

*The G1000 is capable of determining this information accurately but that function is usually removed during training to sharpen our skills!