Take off Distance Procedures

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Take off Distance Procedures

• In this lesson we will be looking at the step by
  step procedures for finding your take off
  distance for a Cessna 152.

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Take Off Distance Chart
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Pressure Altitude (PA)

• The reading on the altimeter when it is set to
  the standard barometric pressure. (29.92).
• Used for performance charts.
• Also referred to as Flight Levels FL180
  18,000 ASL

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To Calculate PA

• Method 1
• Set aircraft altimeter to 29.92.
• Read pressure altitude on the dial.
• Method 2
• 1 inch of mercury equals to 1000 feet of
  altitude.
• Current altimeter setting subtracted from
  standard atmosphere. (29.92)
• If positive number multiply the result by 1000
  and add to your elevation.
• If negative number multiply the result by 1000
  and subtract from your elevation. Examples 1 2

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Example of PA calculation

• Steinbach South Elevation 900 ASL
• Altimeter setting 29.72 Calculator 29.92-29.72
  .20 X 1000 200200 900 1100 ft Pressure
  Altitude

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Example of PA calculation (2)

• Steinbach South Elevation 900 ASL
• Altimeter setting 30.12 Calculator 29.92-30.12
  -.20 X 1000 -200900 -200 700 ft Pressure
  Altitude

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Wind Components
Wind 190/15 knots at SteinbachSouth with the
runways 35/17 How much of this wind is a head
wind and cross wind?
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Wind Components (2)

• ExampleWinds 190_at_15 knots a Steinbach South
  with the runways 35/17
• Chose runway 17, because the winds are reported
  out of 190, thus the winds are 20 degree of the
  runway.
• On the headwind side of the graph find 20 degree
  off the runway and move up the to the 20 knot
  arc.
• The point that the 20 degree line and the 20 knot
  arc meet look straight down and straight to the
  left.
• To the left is the headwind component and down is
  the crosswind component. Cross wind 7
  knotsHead wind 18 knots

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Interpolating Results
If you have a temperature or elevation in-between
the listed number, you will need to interpolate.

• Example Temperature of 17 C at a elevation of
  1000 feet.
• The ground roll at 10 C is 765 and at 20 C is
  825.
• Take the difference from 825 and 765 825-76560
• 17 C is a little more then half the difference
  between 10 and 20. Thus 17 is 70 more then 10 C.
  
• 60 X 70 42
• Add 42 to the takeoff distance at 10C (765).765
  42 807

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Interpolating Results (2)

• Example Pressure altitude of 1300 at a
  temperature of 10 C.
• The ground roll at 1000 and 10 C is is 765 and at
  2000 is 840.
• Take the difference from 840 and 765 840-76575
• Remember that 1300 is a little less then half the
  difference between 1000 and 2000. Thus 1300 is
  30 more then 1000.
• 75 X 30 22.5
• Add 22.5 to the takeoff distance at 1000 (765).
  765 22.5 787.5

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Dry grass runway

• Example if your ground roll on pavement is 765
  and the distance over 50 ft is 1420. What is our
  landing distance on grass?
• Add 15 to the ground roll figure.765 15 880
• To calculate the distance over 50 feet, add the
  15 of the ground roll to the distance over 50
  feet.765 15 880 765 115115 1420 1535

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Practice Question

• You are taking off from Calgary Springbank in a
  Cessna 152. What is your takeoff distance and
  distance over 50 feet with the following
  conditions
• Winds 140/10
• Temperature 30
• Altimeter 29.32
• On the GRASS beside the runway

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Practice Question (Answer)

• Pressure Altitude 29.92-28.92 1.00 X 1000
  10003937 1000 4937 ft rounded up to 5000
  ft.
• Ground Roll at 5000 ft pressure altitude and 30 C
  1315
• Distance over 50 ft at 5000 ft and 30 C 2525
• Runway 16 Headwind 9 knots Crosswind 3 knots
• 9 knot headwind10 off. 1315 10 1183 2525
  102272
• Grass adds 15 to the ground roll 1183 15
  1360
• Grass adds 15 of the ground roll to the distance
  over 50 feet.
• 1360-1183177 2272 177 2449
• FINAL GROUND ROLL 1360 FINAL DIST OVER 50 ft
  2449

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Tundra Tires?
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Practice Question (2)

• You are taking off from Churchill, Manitoba in a
  Cessna 152. What is your takeoff distance with
  the following conditions
• Winds 300/25
• Temperature -30
• Altimeter 30.02

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Practice Question (Answer 2)

• Pressure Altitude 29.92-30.02 -.10 X 1000
  -10094 -100 -6 ft rounded up to 0 ft.
• Use 0 C because there is no temperature lower
  then 0.
• Ground Roll at 0 ft pressure altitude and 0 C
  640
• Distance over 50 ft at 0 ft and 0 C 1190
• Runway 33 Headwind 18 knots Crosswind 12 knots
• 18 knot headwind20 off. 640 20 512 1190
  20952
• FINAL GROUND ROLL 512 FINAL DIST OVER 50 ft
  952

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