I learned to fly at the ripe age of 14 in a converted Steerman PT 17, crop duster. Long before ILS come into being, commercial aircraft used light becons as a form of navigation. They were only as good as the weather. Bad weather no fly, no landings. Then along came GCA (ground control approach) approches, scared the living hell out of you in bad weather but better than the alternative. In some areas VOR approaches worked to a certain degree though not in weather below minimuns. I have made numerious RNAV approches that (obviously) worked for me. My question, do Tropic/Maya aircraft have RNAV systems on board? Unless weather is "really" below minimums, it could be used quite effectivily on approaches to SP. Again, JMHO.