FAA Approves More Precise GPS At SFO


The FAA is allowing San Francisco International Airport to implement a new instrument landing system the airport hopes will allow it to design approaches that reduce noise for its neighbors. The Ground-Based Augmentation System (GBAS) uses ground stations arrayed at the airport to make corrections to errors inherent in the GPS signals that are broadcast by the satellites. The corrected signals are then transmitted to aircraft, offering position accuracy to within an inch compared to 150 feet from regular GPS. That will allow for much higher precision for operations in bad weather.

For now, SFO will use the system on instrument approaches that are already in use but within a few years it hopes to design new approaches that will allow inbound aircraft to stay higher for longer and lessen noise impact. “There are many potential benefits to GBAS, but our primary hope for this technology is to help reduce aircraft noise in our communities,” said Airport Director Ivar Satero. “We have much more work to do, but this is a critical first step.” The SFO implementation is also expected to pave the way for other airports to install the system.

Russ Niles
Russ Niles is Editor-in-Chief of AVweb. He has been a pilot for 30 years and joined AVweb 22 years ago. He and his wife Marni live in southern British Columbia where they also operate a small winery.

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  1. “This is the first certification of the system in the U.S.” – Apart from Houston KIAH and Newark KEWR which have had these approaches for several years now.

    • Hello Mike! I was going to say the same thing. Also, Boeing/Honeywell have had the system up and running in Moses Lake (MWH) where they have used it for testing and certification even longer. For a very long time (until Continental/United lit up EWR and IAH) the MWH system was the only operational GBAS/LAAS anywhere.

  2. It says – to reduce noise – keep em up higher & longer.
    I take it to mean before getting to the outer M.
    If so, ATC can do that now.

    • The GBAS-supported GPS Landing System (GLS) can also allow for curved approaches, which at SFO could mean keeping planes farther out over the water and away from land/people. I don’t know if any of the (few) operational GLS approaches actually USE that capability today, but it’s there.

  3. Well, with universal full hands-off landing, standardized automatic braking profiles and automated turnoff-taxi and we can reduce sequence time to 30 seconds or so. DING – “Captain, this is the flight management system. You have arrived at the gate. Thank you for riding with me.”

  4. So, I know it wasn’t rocking that 1 inch accuracy like this thing does, but isn’t this just WAAS v2?

    Also, that level of precision is nothing short of remarkable, without a doubt. But is that actually getting us much more than say, 6 inches? I fly a Piper Tomahawk Rocket Sled Chick Magnet, and even in that little sports car, there is no procedure, maneuver, or need to ever measure anything with inches. I suppose if I REALLY get froggy some day and decide I want to be featured in one of those creepy AOPA ASN accident chain reenactment videos where they count down the seconds left for a foolish pilot who made a series of bad decisions, I could see if I could measure the rime ice collecting on the surface of the wings in inches… Why do I hear creepy crash video guy saying numbers!?!

    Anyway, far be it for me to criticize an evolution in a technological system. I’m actually known in some circles to consistently bemoan the lack of innovation in our GA sector, which in soooo many cases evolves into a situation where the FAA decreases safety in the name of ensuring safety. Oh no, you can’t replace both 1940’s era tractor magnetos which are designed with a few dozen single points of potential failure and begin self-canibalizing themselves from the inside the moment it gets installed with a pair of solid state, fully digital, variable timing electronic ignition systems which have no moving parts and are so durable that they have no time or life limited components to worry about. You can only install one of those EISs because we must keep you safe by forcing you to retain one of those 1940’s era tractor magnetos to act as a backup to that one EIS. Hmmmmmm What’s that? Those electronic ignition systems are just too new and the FAA wants to wait to see if they actually are safe… I’m sorry, I missed that last part, I couldn’t hear you over that sound of the last 25 years of the entire experimental fleet running on two EISs and not failing… Weird, yeah, let’s wait and see. Smart…

    Anyway, yay for one inch! So I think you guys can move on to something else. Hey, I have an idea! Instead of chasing those steep exponential curves called “diminishing margins of returns”, maybe put that development funding into something that would represent a LOT of juice for a little squeeze! I’ve got an idea, how about we finally make happen what is the promised fusion power in 30 years of the GA sector, unleaded fuel!! Can someone actually go beyond the self congregation, promise heavy press conferences which celebrate the fact that THIS one is different from the previous 45 press conferences announcing a drop in replacement for the long over due for retirement 100LL fuel has been developed and approved and yay! And then nothing. 100LL is nothing short of slow acting poison for our engines, and is the cause of so many of the issues which have plagued this sector for ¾ of a century. Gee, wouldn’t it be nice if our airplane engines didn’t disintegrate from the inside out because we had the audacity to let a week go between flights!!?? If only we could get rid of yet another one of the antiquated relics which were replaced 12 generations ago by everyone else, basic mineral oil used as engine oil…

    I shouldn’t have to regret buying a certified aircraft and not an experimental. Certified aircraft should be safer than experimental, not the other way around like it has become.