Right, after getting used to the basics and having switched our mindsets completely from VFR to IFR flying, it is time to get serious with the IFR procedures! So far we have logged about 9 hours each. It’s a very good thing we are both allowed to sit in each other’s flights, we learn so much by seeing eachother f-up different things and you can process your own difficulties better as well while the other person is flying.
I have had loads of people ask me if I can cover some subjects a bit more thoroughly, things we learn and practice in the sim, to get a feel what it’s like. Let’s start with tracking and drift. This is the bread and butter of the whole course really. Any of the procedures you are trying to fly will become impossible if your grasp of the basics is off. Private and commercial pilots reading this will know the maximum drift formula we use during the basic training is the (windspeed*60)/TAS. As the aircraft’s TAS increases your drift reduces. This is a nice little formula to use before going to fly on a nav, but the amount of times we need to (re)calculate our drift due to different groundspeeds, heights and windspeeds makes us want to simplify the calculations, i.e SWAG IT.. The good thing about most IFR helicopters is that we fly at a speed close to 120 kts. At 120 kts the factor you need to divide your windspeed by to get the drift is exactly 2, in other words, just use half the windspeed for the maximum drift calculations, easy! Step 2 is then to figure out how much of that wind is actually coming from a 90 degree angle. Using the clock system we can figure out the actual drift. See below for the breakdown:
We played around with this quite a bit, using different headings and tracks and having to calculate the figures enroute, while flying the sim. And no, we are not allowed to use the autopilot, nice try.
The next phase was using these to fly a proper holding. Holdings are detailed procedures to safely ‘waste time’ as our very insightful instructor likes to put it. They consist of a fix, which can be an NDB, VOR or even a GPS coordinate. You overfly the fix, use a rate 1 turn 180 degrees in the opposite direction, fly straight and level for 1 still air minute, another rate 1 turn followed by another 1 minute leg to get back to the fix, sounds easy right? Well it is once you do a couple, but once you introduce different entries, ATC, wind calculations, flying accurately and setting the instruments together with doing your checks, things start to add up quickly.
Flying it isn’t even the hardest though for most, it’s the entry type. Imagine all aircraft just rushing to the fix, trying to somehow make the turn onto the hold, it would become one big mess, not to mention the difficulties that will arise putting the thing into the proper lines to follow. There are three ways of entering a hold: parallel, offset and direct, see the picture below that illustrates the paths to follow depending on your location, the blue lines indicate the borders for each of them (110 degrees into the hold from the QDM, 70 degrees out of the hold from the QDM). Picking the right one is crucial and can be demanding as each leg also requires time and wind corrections, FUN! (Honestly, it is)
Holdings are used mainly to separate traffic when things turn busy for the approach area. After having flown in the hold for X amount of time, you are at some point cleared to start the approach procedure. Under IFR, there are 2 main possibilities, a 2D (non precision) or 3D (precision) approach (like an ILS). Depending on what you choose or get told to do, you refer to the relevant approach chart. We flew our first NDB approach today, which is a 2D approach as there is no vertical guidance, only horizontal. The approach was done at Gloucester, which has a nonstandard hold to the left (usually holdings are right hand). NDB approaches require you to be at certain speeds while flying over certain fixes based on a DME distance. If you run behind the figures or behind the aircraft the whole procedure becomes messy and stressful. Staying ahead of the game is key with this and can be achieved easier using a proper planning before the flight, just like with VFR flying! Once you exit the hold (i.e beacon outbound), you pay close attention the DME distance, as all your upcoming actions are based on the distance from the DME. 5 Miles from the DME is defined as 5D. As all of this had to be flown with proper wind and vertical speed corrections, it was a good check to end the day with to see if we actually understood the stuff we covered so far. See below for the relevant chart we used today with some important bits that I highlighted, including the DME distances and their required heights.
Ok, hopefully that shows a bit more what it is about so far, I will obviously keep updating as the interest for more content is overwhelming. Huge shoutout to Clive, our instructor who is providing way more than we could have hoped for! Thanks everyone for all your support and let me know if you want me to cover some other specific items, stay tuned!