How to Calculate Takeoff Distance | Soft Field Takeoff

Calculating takeoff distances isn’t just for the FAA knowledge exam—it’s a critical skill for real-world flying, especially on short grass runways. In this video, we break down how small changes in temperature and surface conditions can make a big difference in your takeoff performance in a Cessna 172.

📌 Topics Covered:
✅ How to use the Cessna 172 POH (Section 5) to calculate takeoff distance
✅ The impact of temperature and pressure altitude on takeoff performance
✅ Interpolation between chart values when exact temperatures aren’t listed
✅ Adjusting for grass runways and why it matters
✅ Why a buffer factor is critical for safe departures

🌡️ Real-World Example:

5°C vs. 20°C takeoff performance comparison
The impact of hotter air (less dense) on runway requirements
Why a 15-degree temperature increase adds over 200 feet to your takeoff run

[stevekirk]

That is explained so well - thank you.

[klausbellroth]

This calculation should always be done prior to landing at a soft and/or short field as the required landing distance is usually shorter than the takeoff distance. You don't want to find yourself in a situation where a takeoff is impossible.

[garyxu]

Will the soft-field technique take a longer distance than the short-field distance that the POH is based on?

[rodrigoehnis]

As you mentioned, it is based on zero-wind. Could you do an example with NON zero-winds? Or to do that we would only have to follow the notes regarding wind? Thanks!

[bartoszskowronski]

I would also want to know how to calculate TIME to rotate. (or smaller speed if runway is very short, and at that speed I can safely stop on remaining runway. something like V1 but for single engine) and start stopwatch at brake release if I don't achieve Vr or (V1) before alarm than abort takeoff.
if that require complex calculations we ALL have powerful computers in our pockets
that would be last call to abort takeoff if performance is NOT like expected,
in case engine not producing expected power and also if pilot make mistake at weather influence on performance or in weight and balance calculations.