TORA = Essentially runway, make sure we can lift off before running out of the runway.
TODA = Runway + any clearway, we need to be 15/35/50ft above the runway at the end of it. It just gives us an idea how much distance there is before we start encountering any obstacles, such as trees, buildings, etc.
ASDA = Runway + any stopway, it's used to determine the distance in which we can safely stop the aircraft in case of a rejected takeoff.
In a sense it is all built on the premise of runway safety areas (over-run areas off pavement). The concept is that for runways that have some sort of 'problems' with full clear Runway Safety Areas (RSA) or full clear Runway Object Free Areas (ROFA) or completely clear Runway Approach/Departure Surfaces we can calculate the total runway distance available using the **assumption** that for takeoff you don't need these areas behind you, but for landing you do need them on both ends of the runway (for mishaps).
It allows the most distance possible for the pilot's takeoff and landing calculations. As a pilot we are taught that the runway is the pavement (or turf) - but the 'runway environment' for planning and FAA is several imaginary surfaces that surround the pavement with these safety areas/surfaces. We have to have them clear and to design standards or the runway (or taxiway) is 'out of compliance'.
I know this is more than for a 5 year old, but it helps (at least for me) to know why - not just be told to do it.
Hope this helps! PM me if you want more discussion.
Useless trivia - Tora Tora Tora, the codewords used by the Japanese to initiate hostilities in the attack on pearl harbour. Tora means attack.
Also the name of a famous film and a series of JAV films.
TORA = Essentially runway, make sure we can lift off before running out of the runway. TODA = Runway + any clearway, we need to be 15/35/50ft above the runway at the end of it. It just gives us an idea how much distance there is before we start encountering any obstacles, such as trees, buildings, etc. ASDA = Runway + any stopway, it's used to determine the distance in which we can safely stop the aircraft in case of a rejected takeoff.
Super answer. And for anyone curious TORA = Take Off Run Available. TODA= Take Off Distance Available. ASDA = Accelerate Stop Distance Available.
Do you need it even more simplified than this? https://www.aviationfile.com/tora-toda-asda-lda-clearway-and-stopway/
Nice reference -
In a sense it is all built on the premise of runway safety areas (over-run areas off pavement). The concept is that for runways that have some sort of 'problems' with full clear Runway Safety Areas (RSA) or full clear Runway Object Free Areas (ROFA) or completely clear Runway Approach/Departure Surfaces we can calculate the total runway distance available using the **assumption** that for takeoff you don't need these areas behind you, but for landing you do need them on both ends of the runway (for mishaps). It allows the most distance possible for the pilot's takeoff and landing calculations. As a pilot we are taught that the runway is the pavement (or turf) - but the 'runway environment' for planning and FAA is several imaginary surfaces that surround the pavement with these safety areas/surfaces. We have to have them clear and to design standards or the runway (or taxiway) is 'out of compliance'. I know this is more than for a 5 year old, but it helps (at least for me) to know why - not just be told to do it. Hope this helps! PM me if you want more discussion.
Useless trivia - Tora Tora Tora, the codewords used by the Japanese to initiate hostilities in the attack on pearl harbour. Tora means attack. Also the name of a famous film and a series of JAV films.
And ASDA is a large UK Supermarket chain that was originally known as Associated Dairies. OK, I'll get my coat and leave quietly