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The Cessna 172S POH only has Short Field Takeoff Distance tables. How do pilots determine ground roll for a normal takeoff on a long field with hard surface?

The examples in the POH only deal with short field takeoff. Similar thing with chapter 10 in the Pilot's Handbook of Aeronautical Knowledge. It's either short field takeoff or referring to charts that don't exist in the Cessna 172S POH.

Do pilots look up the short field ground roll, apply the adjustment factor for headwind and apply another adjustment factor?

The POH says, on page 5-4 "...keeping in mind that the distances shown are based on the short field takeoff technique. Conservative distances can be established by reading the chart at the next higher value for weight, altitude and temperature."

Does that mean to use the chart, but use the row for the next highest PA and the column for the next next highest temp when determining normal takeoff ground roll?

I've searched this forum and haven't found anything applicable.

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In the C172S POH I have, it's on p. ii (Performance - Specifications): 960ft ground roll and 1630ft total over a 50ft obstacle. The note on p. iii says:

The above performance figures are based on airplane weights at 2550 pounds, standard atmospheric conditions, level, hard-surfaced dry runways and no wind. They are calculated values derived from flight tests conducted by Cessna Aircraft Company under carefully documented conditions and will vary with individual airplanes and numerous factors affecting flight performance.

In other words, it's a useful number to know but you're unlikely to get exactly that performance unless you're a Cessna test pilot in a brand new aircraft. If you own the aircraft (or rent it often) you might want to spend some time actually measuring takeoff distances yourself, to see what performance you're really getting.

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  • $\begingroup$ I wonder how one can measure takeoff distance themselves. Without suitable equipment and proper training, one is unlikely to conduct measurements to obtain accurate and usable results. $\endgroup$ – kevin Sep 9 '17 at 21:08
  • $\begingroup$ Ok I found that page. So that would give a reasonable safety margin given that the aircraft fully fueled and with 1 occupant will be lighter and take off faster, not considering actual PA and wind factors? $\endgroup$ – Kinmount Sep 9 '17 at 21:36
  • $\begingroup$ @kevin If you take off on a runway that has a precision approach, there are white bands spaced every 500'. The centerline stripes are usually about 100' apart, so you can use them for guidance as well. Try some takeoffs with various winds and loads and you’ll know what you can expect with your airplane and your skills. Check out the AIM 2-3-3. Runway Markings for details. $\endgroup$ – JScarry Sep 10 '17 at 14:55
  • $\begingroup$ @kevin There are a few options, from just looking out the window to GPS tracking. You only have to be accurate enough for whatever your own scenarios are. $\endgroup$ – Pondlife Sep 10 '17 at 15:00
  • $\begingroup$ @Kinmount I don't really know what you mean about a safety margin. POH values are typically best case, because they're gathered using an expert pilot. But in this specific case, the figure is given with no wind, so if you have a headwind on takeoff then you should need much less distance. As the POH says, there are a lot of variables involved. $\endgroup$ – Pondlife Sep 10 '17 at 15:04

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