In the normal category of my c172, I have a COG range of forward 35.0 aft of datum at 1950lbs or less, with straight line variation to 40.0 inches aft of datum at 2450lbs

The aft range is 47.3 of datum at all weights.

What does this mean.

The datum is the imaginary vertical plane where the horizontal distance is measured.

The ranges above means that my COG that I calculate after doing a weight and balance should fall between that range and those numbers are the maximum and minimum of those limits?


1 Answer 1


enter image description here

source: own work

It means that your centre of gravity needs to be in the hatched area of the diagram. I've assumed an empty weight of 1600lb for the C172.

You have to calculate the weight of the aircraft and the position of the C.o.G. and verify it is within the correct range as depicted.

  • $\begingroup$ Thank you. I was just making sure. $\endgroup$
    – youngpilot
    Jul 28, 2023 at 14:34
  • 1
    $\begingroup$ You're welcome! The normal way of showing appreciation for an answer at this site is to upvote, and if it answers your question, you could accept the answer by clicking the checkmark below the voting buttons. Please wait at least 24 hours before accepting an answer, to give people around the globe some time to put in their answers and comments. $\endgroup$
    – DeltaLima
    Jul 28, 2023 at 14:56
  • $\begingroup$ ok. So for the chart above the forward limit at 1600lbs is 35.0 inches and aft is 47.3 whilst at 2450lbs the forward limit is 40.0? $\endgroup$
    – youngpilot
    Jul 30, 2023 at 15:21
  • $\begingroup$ @youngpilot, yes. That's the right interpretation. $\endgroup$
    – DeltaLima
    Jul 30, 2023 at 16:26

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