Property of Lear Siegler
0°
WIND EFFECT
VARIATION
DEVIATION
Property of Lear Sielger
Terminal Learning Objective
At the completion of this lesson the student will:
Action: Acting as a pilot, plan a flight
Condition: Given a VFR flight mission, required
equipment, charts and publications
Standard: In Accordance With (IAW) Army
Regulation (AR) 95-1, Federal Aviation
Regulation (FAR) Part 91, and Field Manual
(FM) 3-04.240
Property of Lear Siegler
Enabling Learning Objective (ELO) #1
Action: Solve for drift corrections necessary to
maintain the true course
Condition: Given a True Course
Standard: IAW FM 1-240
Property of Lear Siegler
TRUE COURSE
The proposed flight path measured
clockwise from true north.
True North
(Meridian)
clockwise to
flight path
Property of Lear Siegler
DRIFT CORRECTION
wind 270°
The correction applied
to prevent
drifting off course.
Property of Lear Siegler
DRIFT CORRECTION
NOT APPLIED
wind 270°
Headwind = No Drift
Property of Lear Siegler
DRIFT CORRECTION
NOT APPLIED
Left Crosswind =
Right Drift
True Course
wind 270°
Actual Flight
Path
Property of Lear Siegler
DRIFT CORRECTION
NOT APPLIED
Right Crosswind =
Left Drift
Actual Flight
Path
wind 270°
True Course
Property of Lear Siegler
DRIFT CORRECTION
NOT APPLIED
wind 270°
Tailwind = No Drift
Property of Lear Siegler
LEFT DRIFT CORRECTION
IS SUBTRACTED FROM TC
TC = 360°
TC = 360°
DC = 10° L
DC = 10°
LEFT
360°
- 10°
= 350°
Property of Lear Siegler
RIGHT DRIFT CORRECTION
IS ADDED TO TC
TC = 360°
TC = 360°
DC = 10°R
DC = 10°
RIGHT
360°
+ 10°
= 010°
Property of Lear Siegler
TRUE HEADING
The angle measured clockwise from
true north to the nose of the aircraft.
TC +/- DC = TH
WIND 360
TH
DC
TC
Property of Lear Siegler
Questions?
Property of Lear Siegler
Enabling Learning Objective (ELO) #2
Action: Identify the effects of wind on an aircraft
in flight
Condition: Given situational data
Standard: IAW FM 1-240
Property of Lear Siegler
TRACK
THE ACTUAL FLIGHT PATH OVER THE GROUND,
MEASURED CLOCKWISE FROM TRUE NORTH
TN
TR
Property of Lear Siegler
DRIFT ANGLE
THE ANGLE BETWEEN TRUE
HEADING (TH) AND TRACK (TR)
WIND 360
TH
DC DA
TC
TR
WIND IS MORE THAN PLANNING WINDS, DA > DC
Property of Lear Siegler
DRIFT ANGLE
THE ANGLE BETWEEN TRUE
HEADING (TH) AND TRACK (TR)
WIND 360
TH
DC
DA
TR
TC
WIND IS LESS THAN PLANNING WINDS, DA < DC
Property of Lear Siegler
DRIFT ANGLE
THE ANGLE BETWEEN TRUE
HEADING (TH) AND TRACK (TR)
WIND 360
TH
DC DA = DC
TR = TC
TC
WIND EQUAL TO PLANNING WINDS, DA = DC
Property of Lear Siegler
TRACK EQUAL TRUE COURSE WHEN:
1. NO WIND CONDITION
2. HEAD WIND CONDITION
3. TAIL WIND CONDITION
4. DRIFT CORRECTION IS CORRECT
Property of Lear Siegler
Types of Airspeed
Indicated Airspeed (IAS) - the airspeed read
directly from the airspeed indicator.
IAS is not affected by wind.
Property of Lear Siegler
Types of Airspeed
Calibrated Airspeed (CAS) - indicated airspeed
corrected for instrument installation error.
CAS is not affected by the wind.
Property of Lear Siegler
Types of Airspeed
True Airspeed (TAS) - calibrated airspeed corrected
for error due to air density (altitude and temperature).
TAS is not affected by the wind.
4000’ PA, 7° C = 96 KTAS
1000’ PA, 13° C = 92 KTAS
90 KIAS
Property of Lear Siegler
GROUND SPEED
Ground Speed - speed of the aircraft over the ground.
GS is TAS +/- wind speed. Used to calculate time
required to fly a certain distance.
TAS 92 KNOTS
AIRMASS MOVEMENT 10 KNOTS
TAS
92 KTS
WIND SPEED
- 10 KTS
GROUND SPEED = 82 KTS
Property of Lear Siegler
GROUND SPEED
Ground Speed - speed of the aircraft over the ground.
GS is TAS +/- wind speed. Used to calculate time
required to fly a certain distance.
TAS 92 KNOTS
AIRMASS MOVEMENT 10 KNOTS
TAS
92 KTS
WIND SPEED
+ 10 KTS
GROUND SPEED = 102 KTS
Property of Lear Siegler
GROUND SPEED
Headwinds - winds +/- 90° of the aircraft nose reduce
ground speed. TAS minus wind velocity.
Property of Lear Siegler
GROUND SPEED
Tailwinds - winds +/- 90° of the aircraft tail increase
ground speed. TAS plus wind velocity.
Property of Lear Siegler
Questions?
Property of Lear Siegler
Enabling Learning Objective (ELO) #3
Action: Complete the wind effect components of
the VFR flight log
Condition: Given situational data
Standard: IAW the Student Handout
Property of Lear Siegler
Transport a passenger from Hanchey AHP
31° 21’ N, 85° 40’ W to Sikes airport
30° 47’ N, 86° 31’ W. The wind is
260° / 20 kts and will require a 9° DC.
Property of Lear Siegler
H
1. Draw the true course.
Property of Lear Siegler
H
2. Determine wind direction in relation to the true course.
Property of Lear Siegler
TC +/- DC = TH
232° + 9°R = 241°
H
GS will be less than
TAS because of headwind.
3. Complete the wind component
part of the VFR flight log.
Property of Lear Siegler
Fly from Skelly AHP, 31° 18’ N, 86° 07’ W
to Crenshaw Memorial, 31° 51’ N, 86° 36’ W.
The wind is 20015 and the DC is 12
Property of Lear Siegler
Questions?
Property of Lear Siegler
Enabling Learning Objective (ELO) #4
Action: Select the definition of magnetic
variation, agonic and isogonic lines and their
application
Condition: Given situational data
Standard: IAW Fm 1-240 and the Student
Handout
Property of Lear Siegler
VARIATION
The angular difference between
true north (TN) and magnetic north (MN).
TN MN
Property of Lear Seigler
VARIATION
The angular difference between
true north (TN) and magnetic north (MN).
TN MN
NOTE :
Magnetic north is moving,
therefore magnetic variation
changes from one chart
edition to another.
Property of Lear Seigler
AGONIC AND ISOGONIC LINES
Represented on sectional charts as
dashed magenta lines, numbered and
lettered, e.g. 1° W, in 1/2° (30’) increments.
Property of Lear Siegler
AGONIC LINE
A line connecting points of zero degree variation.
There is only one agonic line in the United States.
Property of Lear Siegler
ISOGONIC LINES
Lines connecting points of equal magnetic variation.
Property of Lear Siegler
EASTERLY VARIATION
Compass needle points east of TN
and is subtracted. “EAST IS LEAST”
TN
MN
Property of Lear Siegler
TH = 360°, compass is pointing 10° east
of TN. Must subtract 10° in order to fly to TN.
TC +/- DC = TH +/- VAR = MH
360° + 0° = 360° - 10° = 350°
This example assumes a calm wind.
TN MN
Property of Lear Siegler
MH = 350°, compass is pointing 10° east
of TN. Subtracted 10° in order to fly to TN.
TN
MN
Property of Lear Siegler
WESTERLY VARIATION
Compass needle points west of TN
and is added. “WEST IS BEST”
MN
TN
Property of Lear Siegler
TH = 360°, compass is pointing 10° west
of TN. Must add 10° in order to fly to TN.
TC +/- DC = TH +/- VAR = MH
360° + 0° = 360° + 10° = 010°
This example assumes a calm wind.
MN TN
Property of Lear Siegler
MH = 010°, compass is pointing 10° west
of TN. Added 10° in order to fly to TN.
MN
TN
Property of Lear Siegler
APPLYING VARIATION
Find mid-point of TC, apply nearest
whole degree of variation.
B
A
Property of Lear Siegler
B
1. Find mid-point of course leg.
2. Find nearest WHOLE
degree of variation.
A
3. TC +/- DC = TH +/- VAR = MH
320° + 0° = 320° - 1° = 319°
EAST IS LEAST
Property of Lear Siegler
1. Find mid-point of course leg.
2. Find nearest WHOLE degree of variation.
3. TC +/- DC = TH +/- VAR = MH
090° + 0° = 090° +1° = 091°
WEST IS BEST
B
A
Property of Lear Siegler
MAGNETIC HEADING
Now that you know how to figure out MH, the next
question is “What is it ?”
Magnetic Heading is measured from magnetic
north clockwise to the nose of the aircraft.
MN
VAR
Property of Lear Seigler
MH
Questions?
Property of Lear Siegler
Enabling Learning Objective (ELO) #5
Action: Select the definition of deviation, use of
the compass deviation card and completing
VFR flight log
Condition: Given situational data
Standard: IAW Fm 1-240 and the Student
Handout
Property of Lear Siegler
DEVIATION
Compass error caused by external magnetic
fields such as generators, radios, etc., causing
the compass needle to deviate from magnetic north.
Property of Lear Seigler
DEVIATION
Compass error caused by external magnetic
fields such as generators, radios, etc., causing
the compass needle to deviate from magnetic north.
MN
3
N
33
No deviation,
Compass Heading (CH) =
Magnetic Heading (MH)
Property of Lear Seigler
DEVIATION
Compass error caused by external magnetic
fields such as generators, radios, etc., causing
the compass needle to deviate from magnetic north.
MN
N
33
Deviation due to magnetic field
caused by radio.
Compass Heading (CH)
no longer equals
Magnetic Heading (MH)
Property of Lear Seigler
DETERMINE AND APPLY DEVIATION
1. Determine MH, e.g. 010°.
2. Find number closest to
MH in the “to fly” column.
3. Find corresponding CH in
the “steer” column.
4. Apply difference (2°) to MH.
? Is difference + or - ?
TC +/- DC = TH +/- VAR = MH +/- DEV = CH
010° + 0° = 010° + 0° = 010° + 2° = 012°
Plan a flight from Lowe AHP
31° 21’ N, 85° 45’W
to Brewton airport
31° 03’N, 87° 04’W,
winds 270°/15kts. DC is 9 degrees.
Property of Lear Siegler
SOLUTION
1. Draw course line and
measure TC.
TC
256°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R or L.
TC +/- DC
256° + 9°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R.
3. Compute TH.
TC +/- DC = TH
256° + 9° = 265°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R.
3. Compute TH.
4. Add/subtract VAR.
TC +/- DC = TH +/- VAR
256° + 9° = 265° + 2°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R.
3. Compute TH.
4. Add/subtract VAR.
5. Compute MH.
TC +/- DC = TH +/- VAR = MH
256° + 9° = 265° + 2° = 267°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R.
3. Compute TH.
4. Add/subtract VAR.
5. Compute MH.
6. Add/subtract DEV.
TC +/- DC = TH +/- VAR = MH +/- DEV
256° + 9° = 265° + 2° = 267° + 2°
SOLUTION
1. Draw course line and
measure TC.
2. DC: 9°R.
3. Compute TH.
4. Add/subtract VAR.
5. Compute MH.
6. Add/subtract DEV.
7. Compute CH.
TC +/- DC = TH +/- VAR = MH +/- DEV = CH
256° + 9° = 265° + 2° = 267° + 2° = 269°
For light background reading:
FM 3-04.240, Chapter 1, Paragraph 1-35 through
and Chapter 6, paragraph 6-1 through 6-7
1-41
Questions?
End of Day 4
Property of Lear Siegler
Property of Lear Siegler