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Understanding (LDA) landing distance available and associated variables

Posted: Fri Oct 29, 2021 8:41 pm
by tu144d
So, I was looking through an airport I grew up fairly close to (TJPS).

https://www.airnav.com/airport/TJPS

I'm trying to understand what goes into the computation of LDA for my own satisfaction. Runway 12 is 8004 ft long with a 1882 ft displaced threshold which should yield a landing distance of 6122 ft. I've seen terms such as runway clearway and stopway and even if you include the reciprocal runway's displaced threshold for the roll out which would give you an available landing distance of 5874 ft so I don't understand how the LDA of 5488 ft is obtained. I'd love to understand how this is calculated for my own curiosity

Re: Understanding (LDA) landing distance available and associated variables

Posted: Fri Oct 29, 2021 10:53 pm
by GalaxyFlyer
It’s all here and more. Start with Chapter 3, Runway Design

https://www.faa.gov/documentLibrary/med ... pdf#page57

In brief, it’s not just about declared distances, but application of safety standards for runway protection zone and runway obstacle free zone. If your airport can’t meet the requirements OFF the runway, block off portions of the runway to met those requirements. Runway safe areas is a big improvement and airports that meet them are safer because events resulting in runway excursions don’t become fatal.

Re: Understanding (LDA) landing distance available and associated variables

Posted: Sat Oct 30, 2021 5:45 pm
by tu144d
GalaxyFlyer wrote:
It’s all here and more. Start with Chapter 3, Runway Design

https://www.faa.gov/documentLibrary/med ... pdf#page57

In brief, it’s not just about declared distances, but application of safety standards for runway protection zone and runway obstacle free zone. If your airport can’t meet the requirements OFF the runway, block off portions of the runway to met those requirements. Runway safe areas is a big improvement and airports that meet them are safer because events resulting in runway excursions don’t become fatal.


Much obliged! Very interesting reading on a cold "stay at home" day where I've binged I've everything on Netflix I care too and I can't bear to watch the news.

Re: Understanding (LDA) landing distance available and associated variables

Posted: Sun Oct 31, 2021 1:27 am
by Starlionblue
Skybrary has a good introductory article on Landing Distance Available.

https://www.skybrary.aero/index.php/Landing_Distances

Re: Understanding (LDA) landing distance available and associated variables

Posted: Sun Oct 31, 2021 2:00 am
by GalaxyFlyer
That airport has some interesting declared distances—TORA = TODA, but ASDA was a thousand feet less than either.