Instrument flying as not only three skills, but there is a sequence to them:
It sounds simple. But why then does it get so confusing to know which is the primary instrument and which is the backup, as well as what they’re good for? Could be because when asked what the pitch instruments are, the answer is: Altimeter, airspeed indicator, vertical speed indicator and the attitude indicator. How can it be all of them?
You will be required to know which instrument is primary for the test. In addition, when flying your plane, knowing which to use first comes in quite handy. Here is the gouge that will help you answer the questions for the test, and maybe help with flying the plane.
What will the FAA examiner look at to determine if you’re within parameters for a given maneuver? That will be your primary instrument. Do you have to fly within plus or minus ten knots of your airspeed? Airspeed indicator is primary. Do you have to level off at a given altitude? That is your primary instrument. Let’s try a few.
What is the instrument that provides the most pertinent information (primary) for bank control in straight and level? In this case, how will the FAA know if you’re flying straight? Answer: The heading indicator.
As the power is reduced to change airspeed from high to low cruise, in straight and level flight what are the primary instruments for pitch, bank, and power respectively? Respectively means in sequence.
Pitch: You’re maintaining level flight. What would the examiner be looking at? Altimeter!
Bank: We’re not turning. How do we know? Heading indicator!
Power: We are changing our power. How do we know if we’re reducing the power enough? Manifold pressure gauge or Tachometer!
Think you’ve got it? What is the primary bank instrument while transitioning to any standard-rate turn? Attitude! “Transitioning” is the clue. The turn indicator is just supporting until once in the turn, and then it becomes primary.
What is the primary pitch instrument during roll-in and throughout a constant “altitude” turn? Yep… altitude is the key for altimeter.
The rate of any turn at any airspeed is dependent upon the horizontal component of lift.
What is the horizontal component of lift? In straight and level flight lift must equal weight, thrust must equal drag. When we bank, the horizontal component of lift increases, and the vertical component decreases. Where the vertical component meets the horizontal component, this is how much lift we need to sustain level flight in the bank. As you can see from the diagram below, the blue lift line is far greater in diagram b, than in a. It takes more lift to sustain level in the bank. Tighten that turn and the horizontal line would grow and the vertical component would shrink.
So when you’re asked, why is it we have to increase the angle of attack to maintain a constant altitude of during a coordinated turn? Your answer will be: Because the vertical component of lift has decreased as the result of the bank.
How do you increase the rate of turn, and decrease the radius? Bank more and/or slow down.
During a constant bank level turn, what would an increase in airspeed do to the rate of turn and the radius? Decrease the rate, and increase the radius.
The slower you’re going, the tighter the turn you’ll make. The faster, the wider. The more you bank, the tighter the turn. The less bank… well, you got it now. How about a couple more FAA questions?
When airspeed is decreased in a turn what do you have to do to maintain level flight? Decrease the angle of bank (roll out), and/or increase angle of attack (pull back).
What is the primary “pitch” instrument during a “constant airspeed” descent? Don’t let the pitch confuse you. If you want to maintain constant speed… the answer has to be the airspeed indicator.
What is the primary “pitch” instrument during a constant “rate” descent? How do we see rate? VSI.
By the way… did you know there is an IVSI and a VSI? Previously I mentioned how I used the IVSI during my flying, as a primary instrument. If it wasn’t moving, my altitude wasn’t changing, etc., Well, low and behold most general aviation planes have a “VSI.” The jets I’ve been flying have an “IVSI.” The “I,” being the key letter—Instantaneous. Apparently the VSI lags. But my instructor tells me that once on the glideslope it’s right on.
TRUST BUT VERIFY:
Since we’ve been told to believe our instruments. There is another part to that statement—verification.
What if our instruments have a failure? Well your primary instruments will certainly differ. For example: If the gyro heading indicator fails, the primary bank instrument for in unaccelerated straight-and-level flight is the magnetic compass.
Compare your instruments to determine which is faulty. Don’t blindly follow a failed instrument. A good course of action is to cover that failed instrument so you won’t be a rabbit in the headlights.
Enjoy the journey! Safe flying with your head in the clouds.
Instrument Navigation is up next!
Note: All red and italic statement is an actual FAA Instrument test question. Learn a couple each day, and you’ll be on your way to success.
This article was originally published on FlyingTraining.net. It was tweeted 10 times and shared on Facebook by 2 people.