I'm planning my cross country journey for my flight test and it seems I forgot how to calculate my indicated airspeed.

The indicated airspeed must be from the POH, right? The the true airspeed is from the IAS and TAS correction table in the POH? Then the ground speed is based on TAS, with the wind factored in?

I'm flying a mid-late 70s Cessna 172 skyhawk.

  • 1
    $\begingroup$ If you are planning a flight a you forget how to do something, ask your instructor. Anyway since it is a flight test you should be more familiar with all steps involve before you start hurting yourself. $\endgroup$
    – vasin1987
    Commented Mar 3, 2016 at 18:56
  • 1
    $\begingroup$ Don't overdo it. Put something reasonable in the filed flight plan. No one will have a problem with a slightly inaccurate airspeed in a filed flight plan. $\endgroup$
    – Wirewrap
    Commented Mar 3, 2016 at 21:00

1 Answer 1


You do not calculate indicated airspeed: It is an indicated value, you read it from the airspeed indicator. (I suppose you can calculate it if you really want to, but I've got no idea why you would want to do so in the context of flight planning.)

You determine what airspeed to use for flight planning purposes using your aircraft's performance data (from the POH or other manufacturer documents): There will usually be either a chart or a table giving true airspeed as a function of power setting and density altitude.
(True Airspeed is a more useful number for planning purposes as it saves you a calculation.)

Performance Table (Cessna style) Performance Chart (Piper Style

When in flight you can calculate your true airspeed based on the indicated airspeed and density altitude. You can then compare this to your planned figures from the performance charts to determine if adjustments are necessary to your flight plan (ETA, Fuel use, etc.)

  • 2
    $\begingroup$ It should go without saying (but I'll say it anyway) that the images above should not be used for flight planning purposes - hence why I intentionally cropped out the aircraft models from the pages. $\endgroup$
    – voretaq7
    Commented Mar 3, 2016 at 19:15

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .