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How to Convert KTS to IAS

Dead reckoning, a common form of navigation for light aircraft, uses variables including airspeed, altitude and distance to calculate a course from one fixed point to another. Knowing the true airspeed, or KTAS, of an aircraft is essential for accurate results, as the airspeed displayed on the indicated airspeed, or IAS, is not corrected for the effects of altitude. Indicated airspeed is easily calculated from true airspeed, measured in knots, using a standard formula.

Things You'll Need

Flight plan
Calculator

Instructions

- 1
  Make a note of the true airspeed that you wish to convert to indicated airspeed. Check that this is given in knots, or KTs.
- 2
  Check your flight plan and confirm the altitude at which you intend to fly in thousands of feet. Write this down. For example, if you intend to fly at 8,000 feet, write down 8.
- 3
  Calculate 2 percent of the value that you wrote down. For example, if you wrote down 8 your answer is 0.16.
- 4
  Add 1 to your answer. Divide the true airspeed that you wish to convert by this figure. For example, if your answer is 0.16 and your true airspeed is 180 KTs, then your result is 155.17 knots. This is the true airspeed in KTs converted to IAS.
- 5
  Check your calculation. Record the indicated airspeed on your flight plan.

Aviation