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Take a look at the new Wide Area Augmentation System (WAAS). Soon, nearly all airports will have an ILS like approach. WOW. web page
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For contingency ops, we would perform self-contained precision approaches using the onboard GPS. A measured point on the runway would be selected with an inbound course and descent angle entered, and GP as well as azimuth indications would be fed to the command bars on the ADI. Of course, none of this was in any way TERPs out, but was pretty darn accurate.