1. Navigation Instruments Overview & Objectives
1. Understand the navigation functions of the following instruments:
Clock
Airspeed Indicator
Altimeter
Compass
Turn-and-Slip Indicator
Attitude Indicator
2. Explain the different types of altitude
3. Calculate speed, time, distance
Calculate TC, TH, MH, CH
In this lesson we will discuss:
1. The Clock
2. Airspeed Indicator
3. Altimeter
4. Types of Altitude
5. Compass
6. Turn-and-Slip Indicators
7. Attitude Indicator

2. Clock Simplest & one of most important navigation instruments
One of first indications of trouble … starting to miss your planned times over checkpoints.
Fuel consumption is
computed in time ...why?
Aircrews want to know how
long they can stay airborne
The Clock
The simplest and one of the most important instruments used for navigation. The estimated time of arrival (ETA) is frequently updated.
One of the first indications of trouble occurs when you start to miss your planned times over checkpoints. This usually means that wind shifts have occurred.
Fuel consumption is computed in time. Any changes in time affect the amount of fuel that you will have at your destination.
Any good timepiece is suitable for indicating elapsed time, and it is not necessary to have an elaborate clock or chronometer for simple navigation.

3. Airspeed Indicator Informs pilot of speed through the air in:
Miles Per Hour(MPH) or Knots
Dial marked w/ colored areas to show max allowable speeds, normal speeds, approved flap operating speeds, etc.
How does it work?
Measures pressure of air rammed into a pitot tube
Airspeed Indicator
Informs the pilot of the speed through the air in terms of miles per hour and/or knots.
It measures pressure of air rammed into a pitot tube caused by the aircraft’s forward motion.
The pitot tube is mounted so that air reaches it without being disturbed by the airplane.
On a single-engine airplane it might be mounted on the leading edge of the wing or on a strut.
On a two-engine airplane, it probably will be mounted under the nose of the fuselage.

4. Critical Thought Activity: “Car” Speed Challenge
Going 60 mph, drive for 2 hours, how far?
60 miles 2 hours
1 hour x 1 = 120 miles
Drive 120 miles for 2 hours, how fast?
120 miles
2 hours = 60 mph
(Trickier) Going 60 mph, drive for 120 miles, how long?
60 miles 120 miles
1 hour x 1 =
1 hour miles
= 60 miles x 1 = 2 hours

5. Critical Thought Activity: “Air” Speed Challenge
Flying 180 knots, fly for 3 hours, how far?
180 NM 3 hours
1 hour x 1 = 540 Nautical miles
Fly 600 nautical miles for 2 hours, how fast?
600 NM
2 hours = 300 knots
(Trickier) Going 400 knots, fly for 1200 miles, how long?
400 NM NM
1 hour x 1 =
1 hour NM
= 400 NM x 1 = 3 hours

6. Altimeter Measures altitude
Altitude - vertical distance above sea level
How does it work?
Uses an aneroid barometer
Senses the outside pressure
What altitude is this?
1,400 Ft
10,000 Ft
1,000 Ft
100 Ft
Altimeter
Measures altitude, the vertical distance above a level plane of reference, such as sea level.
Most light planes use an aneroid barometer as an altimeter. It measures the atmospheric pressure at flight level, that is, the weight of the air above the craft.
Air pressure around the altimeter’s sealed diaphragm decreases and the diaphragm expands.
When the airplane returns to a lower altitude and the atmospheric pressure increases, the diaphragm contracts.
The results of this expansion and contraction are transmitted by levers and gears to indicator hands on the dial of the altimeter. The pressure altitude is shown on the dial as feet above sea level.

7. Altimeter
Altimeters are set w/ current local pressure readings (at weather station) when near the ground … why?
To avoid terrain (i.e. hitting the ground)
Set to when above 18,000 ft … why?
To keep higher altitude airplanes apart
One of the most common altimeters has a dial face graduated with numerals from 0 to 9.
The three pointers on the face of the altimeter each represent different altitude measurements.
The 100-foot indicator makes one complete revolution for each 1,000 feet of altitude. Each numerical reading is made in hundreds of feet. The intermediate, or second pointer, makes one full revolution for each 10,000 feet of change in altitude. The scale is then read in thousands of feet. The third pointer reads in tens of thousands, and one revolution represents 100,000 feet.
An increase in altitude will give inexact readings. To obtain exact readings, the indicated reading must be corrected for atmospheric pressure, temperature, and instrument error.
To achieve vertical clearance, all aircraft in a given area are given a particular level known as an altimeter setting. Altimeter settings may be generally defined as the pressure reduced to sea level in inches of mercury for a given reporting station. Prior to takeoff, the pilot should set the altimeter with the correct altimeter setting. This setting is furnished by the tower and is set on the barometric scale of the altimeter. Setting the altimeter results in a reading of indicated altitude. Flying at an indicated altitude ensures traffic separation, since all properly set altimeters in the area are equally affected by whatever pressure and temperature conditions may exist. Pilots need not make allowance for nonstandard atmospheric conditions but must keep their altimeters adjusted to the latest altimeter setting. These settings can be obtained from radio stations or control towers along the route. If there were no means available to change the altimeter setting, flight would be extremely hazardous, especially over mountainous areas.
A change of 1/10 of an inch of mercury in the pressure setting will result in a change of 100 feet in altitude. If there is a change of 1 inch in the pressure setting, the altimeter reading will be changed by 1,000 feet. While flying along the flight path, the pilot must set his altimeter to the reading given by the nearest Flight Service Station. At altitudes above 18,000 feet, everyone uses an altimeter setting of The altimeter can be one of the most important of the navigational instruments, and every pilot must understand its operation.
Knob & Setting

8. Compass Indicates direction
Most basic & important navigation instrument
All airplanes have a magnetic compass
Only totally reliable direction-sensing device
How does it work?
Senses Earth’s magnetic pole
Compass
The most basic and most important navigation instrument is the magnetic compass.
Every airplane has a magnetic compass because it is the only totally reliable direction-sensing device in the airplane.
Heading indicators are in most airplanes today.
The heading indicator has all the directions printed on its compass card which the pilot can see, but behind the compass card is a gyroscopic device.
The gyroscope begins operating only when the airplane is started. The pilot must set the heading indicator before takeoff and this is done by using the magnetic compass reading as a reference.
Since the gyroscope may change as the airplane is maneuvered, the pilot must cross-check reading from the heading indicator with those shown by the magnetic compass. If the readings are not the same, the heading indicator must be reset.

9. True North vs Magnetic North
Follows a longitude line to the actual “spinning” north pole
Magnetic North
Actual place where magnetic field emanates
Difference b/w true & magnetic north is the variation

10. Types of Headings True Course (TC) “Track”
TC = off the map (referencing True North)
True heading (TH)
TH = TC ± Wind Drift (calculated)
Left is +, Right is -
Magnetic heading (MH)
MH = TH ± Magnetic variation
West is + (best), East is – (least)
Compass heading (CH)
CH = MH ± Compass deviation (instrument errors)
TC ± drift = TH ± Magnetic Variation = MH ± compass deviation = CH

11. Critical Thought Activity: Heading Challenge
Give the pilot a heading to fly:
I Want to fly a course across my map (measured off a longitude line) of 030°
My calculated wind drift is 3° Left
Magnetic variation is 10°E
Compass Deviation is +2°
What is my Compass Heading?
(HINT?)
True Course (TC) ± drift = True Heading (TH)
TH ± Magnetic Variation = Magnetic Heading (MH)
MH ± compass deviation = Compass Heading (CH)
Answer
TC = 030°
TH = 030°+ 3° = 33°
MH = 033° - 10° = 023°
CH = 023° + 2° = 025°

12. Turn-and-Slip Indicator
Indicates direction & quality of the turn
If airplane is “slipping” toward the inside of the turn:
Ball moves in that direction (low side)
If the airplane is “skidding”
Ball moves in other direction (high side)
The ball will stay in the middle
if the turn is properly coordinated
Turn-and-Slip Indicators
Two instruments in one. The turn indicator, which is the needle, indicates the direction of the turn and the rate of turn. The ball in the glass tube (called the inclinometer) indicates the quality of the turn.
The turn indicator, which is the needle, indicates the direction of the turn and the rate of turn.
The ball in the glass tube (called the inclinometer) indicates the quality of the turn.

13. Vertical Speed Indicator
Tells pilot what rate airplane is climbing or descending in feet per minute (fpm)
If each mark is 100 fpm…
What is this
airplane doing?
Climbing 200 fpm
Vertical Speed Indicator
Tells the pilot at what rate (in feet per minute) the airplane is climbing or descending.
It works like an altimeter in that the indication is merely a reflection of atmospheric pressure changes.
The more rapid the pressure change, the greater the rate of climb or descent.
The needle rotates clockwise to indicate climb, and counter-clockwise to indicate descent.

14. Attitude Indicator
A gyroscopic instrument that shows the horizon of the Earth in relation to the attitude (pitch & bank) of your airplane
Has a scale to indicate the
degrees of pitch & bank
Attitude indicator is also called
the artificial horizon
A small stationary aircraft symbol is YOU
The instrument also has a scale, which indicates degrees of bank. The attitude indicator is also known as artificial horizon and as gyrohorizon.

15. Critical Thought Activity: Attitude Indicator Challenge
A small stationary aircraft symbol on the instrument case is the point of reference to the horizon.
If the small aircraft is above the artificial horizon, the airplane is nose high.
If the small aircraft is below the horizon, it is nose low.
In a right turn, the artificial horizon will appear to the pilot to be tipped to the left.
If the turn of the airplane is nose low, the index will be below the slanted horizon.

16. Critical Thought Activity: Attitude Indicator Challenge (Part 2)
A small stationary aircraft symbol on the instrument case is the point of reference to the horizon.
If the small aircraft is above the artificial horizon, the airplane is nose high.
If the small aircraft is below the horizon, it is nose low.
In a right turn, the artificial horizon will appear to the pilot to be tipped to the left.
If the turn of the airplane is nose low, the index will be below the slanted horizon.