Upgrading the Garmin 430/530 for WAAS
In the summer of 2007 I upgraded my Garmin 530 to the WAAS enabled 530W. It seemed from my research beforehand and then my observations afterwards that Garmin really hadn't done a very good job of going into detail on just what you get with the upgrade. So let me try to paint a more complete picture, with some of this text quoting Garmin sources.
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5 Hz Refresh
A few notes on flying WAAS Approaches
Squawks as of Sep 18, 2007
Breaking News (Sep 21 2007)
GNS 430W/530W Software 3.30 released (Aug 2009)
First and foremost (and most obviously), you do gain the WAAS capability. This lets you fly WAAS precision approaches, which are growing in number at a very rapid pace. Glide slope information will be displayed for GPS approaches on the glide slope indicator, and in my case couples very nicely with my KAP140 autopilot. You also receive vertical guidance on many non-precision approaches. You also are provided integrity information and alarms in near real-time (within 6-8 seconds), vs notifications that previously could take up to 15 minutes. I'm not going to cover all the ins and outs of WAAS approaches here.
5 Hz Refresh
A few notes on flying WAAS approaches
There is some training involved in learning how to fly the WAAS approaches. The best explanation I've seen comes not from Garmin's documentation, but this description from IFR Refresher magazine:
If an approach is a standard GPS approach with no vertical guidance then "LNAV" will be displayed. If a GPS approach with LNAV-only minimums has a vertical profile coded into the database - referred to as advisory vertical guidance (Jeppesen chart users will see this as a dashed line on the vertical profile) - then "LNAV+V" will be annunciated, meaning that an electronic glidepath is provided via the glidescope pointer, allowing for a stabilized descent to the LNAV MDA. This vertical guidance is advisory and therefore may be ignored, which is good news for pilots who prefer the "chop and drop" method of flying a non-precision approach. If the GPS approach has LNAV/VNAV minima, "L/VNAV" will be annunciated and the approach is flown just like an ILS, using the vertical deviation information displayed via the glidescope pointer.
If the GPS approach has LPV minima, then the unit has a bit more work to do. About one minute prior to reaching the FAF, the unit will check the required Horizontal Alarm Limit (HAL) and Vertical Alarm Limit (VAL) to ensure the GPS position integrity is within the limits to complete the LPV approach. If the HAL or VAL limits are exceeded, the approach will be downgraded to a non-precision approach indicated by "LNAV" on the moving map, a message will display indicating that the approach is downgraded ("Approach downgraded - Use LNAV minima"), and the glidescope pointer will be flagged. In this case, you may continue the approach using the published LNAV non-precision minimums.
When flying the vertically guided approaches (LPV, LNAV/VNAV, and LNAV with advisory vertical guidance), the glidescope pointer will come into view prior to the final approach fix and you intercept it and fly it down to the DA or MDA, just as you would an ILS.
Squawks as of Sep 18, 2007
Breaking News (Sep 21) - There's a free warranty software update (Ver 3.0) that is scheduled for release at the end of October for the 430W and 530W. The upgrade will be performed by your local Avionics shop just by inserting an upgrade card into the right side 430W slot or the appropriate slot in the 530W. Here are the new capabilities that can be expected:
GNS 430W/530W software 3.30 released (Aug 2009) - This is a warranty field upgrade listed as "mandatory", free if installed by July 31, 2010. It's odd that the panning bug reported by some is not "fixed". Here's what Garmin says it fixed:
Last edited: 05.Aug.2009