Aircraft InstrumentsGroup C: Second Year Advanced

Essential Questions

• What are the instruments?

• What do the instruments do?

• How do the instruments work?

• How do you read the instruments?

The Standard “Six Pack”

• 6 most important instruments all side-by-side

Pitot-Static System Instruments

• Airspeed indicator• Vertical speed indicator (VSI)• Altimeter

• Pitot tube• Static port

1. The airspeed indicator shows speed through the air --- not over the ground.

The pitot tube on the wing catches on-rushing air. This “ram air” is compared to “static” air to determine air speed.

The static port measures static or still air – air that is not affected by the airplane’s speed through the air

2. The vertical speed indicator uses changes in air pressure to indicate rate of climb or descent.

VS is read in feet per minute

This airplane is descending at _______ feet per minute.180

3. The altimeter measures air pressure outside the airplane and compares it to air pressure at sea level to determine altitude.

Like the hands of a clock, the long hand shows smaller increments (100s of feet) while the shorter hand shows larger increments (1,000s of feet). The hand with the triangle on the end shows the largest increments (10,000s of feet).

This altimeter is reading ________ feet.1,719

Altitudes

• 1. MSL• Mean sea level• Read by the altimeter• Feet above sea level

• 2. AGL• Above ground level• Feet above the ground• No instrument indication; altimeter reads

only MSL and not AGL

Altimeter Setting

• Barometric Pressure - air pressure at your elevation; altimeter setting always set to barometric pressure at sea level

• Standard is 29.92

• Barometric pressure always decreases as altitude increases

• Listen for altimeter setting during ATIS

Blockage of the Pitot-Static System

• Can be caused my moisture, ice, dirt, insects, etc.

• Blocked pitot tube:• False airspeed indication• Airspeed gradually drops to 0• If drain hole is blocked as well, airspeed

indicator will act as altimeter• Blocked static port:

• Airspeed indications are lower than actual

Blockage of the Pitot-Static System

• Frozen altimeter• Constant 0 on VSI

The attitude indicator gives an artificial horizon to show the pilot the airplane’s position in relation to the ground.

Here, the airplane is banking left with its nose on the horizon —where brown “ground” meets blue “sky.”

Tells you 3 things:

1.Degrees of pitch

2.Climb or descent

3.Degrees of bank

The turn coordinator shows if the wings are level or banked. The position of the ball indicates if the airplane is coordinated during a turn.

The ball is centered when the turn is coordinated by therudder.

Turn Coordinator

The heading indicator shows you which direction you’re going relative to Earth’s latitude and longitude lines.

Since Earth is a sphere, there are 360 numbers, each being a different direction. For example, east is 90 and south is 180. On the heading indicator, the last 0 is omitted.

Runway numbers work the same way that the numbers on the heading indicator do. The last 0 is omitted and the numbers on the runway match the number on the heading indicator, +/- 5 degrees.

When landing here, your heading indicator should read 27 because you’re landing on runway 27, which is actually 270 degrees.

Other Instruments

• Instruments that you look at less than the main six including fuel indicators, oil temperature, RPMs, VOR, ADF, suction, ammeter, etc.

Quiz Time!

• Your attitude indicator has just failed. What other instruments can you use combined to read the same information that the attitude indicator tells you and why?• Turn coordinator - indicates whether

you’re banking or not• VSI - indicates climbs and descents

(remember 4 second delay!)

Quiz Time!

• The elevation at PDK is 1,003 feet. With the airspeed indicator set at the correct pressure setting, what will your altitude be AGL when the altimeter reads 3,412 feet MSL?• 2,409 feet AGL

Quiz Time!

• If both the pitot tube and the drain hole are blocked, what will the airspeed indicator do?• Changes in static pressure will make the

airspeed indicator act as an altimeter.

Quiz Time!

• What is the standard altimeter setting?

• 29.92

Quiz Time!

• What is the VSI measured in?• Feet per minute

Quiz Time!

• Elevation: 564 feet• Altitude AGL: 1,954 feet• Airspeed Reading?

• 2,518 feet MSL

Quiz Time!

• If the altimeter is reading 4,304 feet AGL, what is your altitude MSL?• The airspeed never reads altitude AGL.

Ok, that’s it.

Quick and simple, right?

• If you have any questions, email me at logan@centennialaviationclub.com