Originally Posted by
back to Boeing
Cat 1 minima are generally 200’/550m. Out of curiosity. How long have those limits been imposed and why. Did some person one day just decide “yup that’s what pilots can fly to so that’ll be the minima”. Or is there a more technical reason?
ILS technology goes back to the 1930's. I'm not sure when the 200' basic minimum was adopted, but it's been at least 40 years, and I presume it is a function of the position tolerances of the equipment (ground and aircraft). Assuming there are no issues with terrain, obstacles or antenna interference, lower minimums are possible with the additional equipment and crew training, but all of those cost money to provide. Airports and operators have to decide if the need for the lower minimums justify the investment.