# Confused about screen height definition

I’m a bit confused about screen height definition and I’m seeking help to understand it. I understand that this height for landings is at least 50 ft above the landing threshold for all airplane categories. For takeoff is at least 50 ft or more for Normal and Utility categories and at least 35 ft or more for the Transport category. My question is: For takeoffs is this screen height measured above the departure end of the runway (or above the end of the clearway if any) or it’s measured when a Piper for example is 50 ft above the runway after taking off?

If it’s measured above the DER, does that mean that the actual takeoff DISTANCE of a runway with no clearway will be the entire runway length always? Since the definition of Takeoff Distance is the distance from the Brake Release Point to when the plane crosses the screen height?

Thank you!

For takeoffs is this screen height measured above the departure end of the runway (or above the end of the clearway if any)

For the takeoff distance available calculation, yes this is correct

or it’s measured when a Piper for example is 50 ft above the runway after taking off?

This is correct for the takeoff distance required calculation.

If it’s measured above the DER, does that mean that the actual takeoff DISTANCE of a runway with no clearway will be the entire runway length always?

Yes, this is known as the "balanced field length", when TODA = TORA = ASDA

• This post is 5mo old so maybe something has changed but IFR departure procedure is 35ft over the departure end of runway for Cat A aircraft (Pipers). This 35ft is measured for the usable runway length for takeoff. The answer above is correct but just know 35ft is your magic number in the US. It may be 50ft in other countries not sure though. Commented Feb 12 at 18:21