Hi guys, it's been a while been kinda busy finishing up all the instructor ratings.
I hope the relief band is working for ya keep us posted on your progress.
As for the 4-Step Scan. It's not on the Machado book, it's on his video and according to him it was developed by some hard core airline check captain dude. I live by it and it's saved my butt a few times flying in the soup with a dying Attitude Indicator. Anyway here's the jist of it:
Music Scan: for those who don't know this is simply the process of scanning 2 or more instruments with 1 of the instruments as the primary. The "music" part of it is that you will be counting just as if you were counting the beat to music, such as "One and Two and One and Two and ... etc" I'll explain this further in step 2.
So here's the 4-step scan:
Step 1
Set the attitude (pitch/power/trim/bank) using Attitude Indicator. This assumes you have a very good idea of the attitude that will give you the desired performance (aka knowing your airplane)
Step 2
Inverted Music scan the inverted V instruments (TC, AI, VSI). We do this to verify that the AI is giving us correct information. So we'll check any turning trend with the TC and any altitude change trend with the VSI. Here's how the "music" scan goes for this step. You will look at the VSI and say "One", then look at the AI and say "and", then look at the TC and say "Two", back to the AI and say "and", then to the VSI and say "One", and so forth and so forth til you verify everything is Kosher. Now what's the importance of this you ask ? Well think for a second, these three instruments usually operate on three separate systems, AI (Vacuum ), TC (Electric), VSI (Pitot-Static). So we can see how this will help us find problems with any of the systems. What do we do when the instruments don't agree ? Well then you have to think. In the interest of keeping this short I'll just list what to do:
- AI and TC disagree: Use the Compass to verify turn
- AI and VSI disagree: Pull the alternate static source valve and verify climb/descent
The reason for using the compass and the alternate static source is that you can't rely on any other instrument that is part of any system that is suspect of being in error
Step 3
Music-scan Primary instruments and trim the airplane. Not gonna go into this much because the primary/supporting concept is in just about every book out there. Just remember there's always 3 primary instruments, one each for Pitch, Bank, and Power. Usually the primary instrument will be the one that gives you a numerical value for the desired performance. So for turning to a heading it's the HI, for holding altitude it's the Altimeter, Airspeed indicator for a constant speed climb, etc.
Alright so we do the same thing, music scan the primary instruments against the Attitude Indicator, this will help you trim out and get the airplane set up properly. So just for example here I'll go through the music scan in this step really quick. We just got our final approach clearance, "81H, turn left HDG 060, maintain 2000 til established, cleared ILS 3 approach". Ok so our primary instruments are Pitch (Altimeter), Bank (HI), Power(Airspeed Indicator, this may be questioned by some but it all depends on how you like to fly). Okay so same as with the Inverted V we look at say the Altimeter and say "one", back to the AI and say "and", look at the HI and say "two", back to the AI and say "and", etc etc etc. (this is so much easier to expalin in an airplane, lol) The basic purpose here is to maintain the attitude with the AI while refining it with the primary instruments.
Step 4 (finally)
Circular-scan the big 6. Huh ? yea this is the easy one and what most of our scans look like when we start flying instruments. Here we basically go around the big six instruments checking everything and making little corrections as necessary, this is what you will do when you're cruising most of the time.
Couple of things to keep in mind. Don't take everything literally, the purpose of the music scan is not just to say "one, and two, and, one, and , two, etc etc etc" The purpose is to force yourself to scan, it works trust me. A lot of times inexperience pilots have trouble with the scan because they don't force themselves to scan instruments, saying the one's and two's out loud or just to yourself helps you do this.
This method relies on the AI, this is why the inverted V procedure is so vital to seeing your grandchildren grow up. Why is it important to do this? well a lot of times when we get busy in the cockpit especially in single pilot IFR we will become overwhelmed with flying, navigating, communicating, etc, etc, etc. Using the music scan in these situations can really make your life simple. Say you're flying along and you start getting busy, everyone who's gone through instrument flight training has had the 90 degree heading and 300 foot altitude deviations when you go tune in the local VOR. Using the music scan, you will never be away from the attitude indicator for more than a few seconds when you accomplish other tasks. What I do is that I will be constantly verifying the AI using the inverted V scan. Like that when I get busy I can rely on my AI to scan against when I need to tune in a VOR or read a chart or anything else. You will basically music scan your "task" against the AI. So if you're tuning and ID'ing a VOR you will get the first few digits of the frequency in, then look at the AI and check your attitude, back to the VOR tuning, back to the AI, then back to the VOR to finish tuning or ID'ing, or getting the Ident from the chart, etc. If you find yourself staying on the VOR or any "task" for too long and your attitude changes, start saying the "one", "and", and "two's" out loud, it will remind you to go back to the AI
One other thought. This doesn't mean that you forget about al the other instruments, remember you still have supporting instruments and don't forget to monitor the engine instruments periodically. Just do what feels comfortable, this is by no means a complete explanation so if you want to try it make sure you understand what to do.
Alright my hands are very tired, I used to be a software engineer and typed all day but now I can barely type all this w/out my hands freaking out.
Hope this helped some. If you're interested get the Rod Machado video he explains it much better than this. I will also try to put this into a good document and e-mail privately to anyone who is interested but I'll shoot out an e-mail to Rod to make sure he won't sure me or something. J/K he's a nice guy....
Alright that's it for today, any questions or comments feel free to PM or e-mail me at
hbenalcazar@yahoo.com ...