WAAS Now Available

Guest Discussion
1

WAAS IS NOW AVAILABLE, FAA SAYS

After a successful 21-day stability test, the
From today’s AOPA e-Pilot. Although the WAAS system is only available for VFR right now, soon it will be available for IFR too. When will Garmin be selling WAAS upgraded units?

Wide Area Augmentation System (WAAS) is now available for aviation use, the FAA announced Thursday. The test demonstrated that the system can operate without interruption, providing a stable and reliable signal to augment GPS units. Raytheon will operate the system for the FAA on a continuous basis, but will interrupt it occasionally to upgrade or test the system. The current WAAS signal is available to pilots to increase situational awareness during VFR operations and on the airport surface. Until the system design is completed and initial operational capability is declared, WAAS is not approved for IFR.

2

Does anybody know what this actually means? Do you need a special GPS receiver to take advantage of this? I know that the WAAS correction data is broadcast on the same frequencies as the GPS satellites, so the same hardware can presumably receive the signal, but it’s not clear (to me) if this just means the GPS receiver sees additional “virtual” satellites, or if the receiver needs extra capabilities to use it.

I’m also puzzled as to just what the WAAS is meant to achieve. While it improves accuracy, it’s still not good enough for precision approaches, and it can’t improve availability, since if the GPS is turned off, WAAS can’t function. So the only real benefit is integrity, since it can presumably detect errors in GPS data.

Can anyone out there enlighten me?

3

What follows is an official response to my inquiry to Garmin regarding the WAAS capability of the GNS 430/530 series, and the effect of the availability of VFR and future IFR WAAS capaibility:

TSO C146 (Stand-Alone Airborne Navigation Equipment using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS)) is now released. We have begun to analyze exactly what it will take to incorporate WAAS into the GNS 430/530 products.

Recently, the FAA has announced that the WAAS signals are available for “VFR use”. Essentially, these are test signals which may be discontinued at any time without notice. Unfortunately, this provides no benefit to the users. (no IFR use, no enhanced integrity, little additional accuracy over GPS now that Selective Availability (SA) has been discontinued). As there is currently no immediate benefit to the user from WAAS (no precision approaches yet defined, and the aforementioned), we also do not see immediate pressure to offer this functionality in a hurry, but rather we will take our time and do it right.

We currently do not envision offering WAAS augmentation to our GNS 430/530 products until Initial Operational Capability (IOC) is declared on the system, which is currently scheduled for 2002.

As the precise details of what will be required to upgrade the GNS 430 to WAAS are currently unknown, pricing for this future upgrade has not yet been established. At a minimum, the unit will need to be returned to the factory to have new TSO markings applied. There will be a software upgrade required, and as of yet we do not know if a hardware upgrade will be necessary.

Thank you and best Regards,

Bill Stone
Avionics Product Manager

GARMIN International

WAAS IS NOW AVAILABLE, FAA SAYS

After a successful 21-day stability test, the
From today’s AOPA e-Pilot. Although the WAAS system is only available for VFR right now, soon it will be available for IFR too. When will Garmin be selling WAAS upgraded units?

Wide Area Augmentation System (WAAS) is now available for aviation use, the FAA announced Thursday. The test demonstrated that the system can operate without interruption, providing a stable and reliable signal to augment GPS units. Raytheon will operate the system for the FAA on a continuous basis, but will interrupt it occasionally to upgrade or test the system. The current WAAS signal is available to pilots to increase situational awareness during VFR operations and on the airport surface. Until the system design is completed and initial operational capability is declared, WAAS is not approved for IFR.

4

Does anybody know what this actually means? Do you need a special GPS receiver to take advantage of this? I know that the WAAS correction data is broadcast on the same frequencies as the GPS satellites, so the same hardware can presumably receive the signal, but it’s not clear (to me) if this just means the GPS receiver sees additional “virtual” satellites, or if the receiver needs extra capabilities to use it.

Yes, you will need to upgrade an existing GPS receiver, if it is WAAS upgradable . . . and the Garmin GNS 430 is supposed to be. However, Garmin has yet to offer the upgrade or provide a WAAS enhanced version of its product as yet. The upgrade, I understand, is not going to be inexpensive and may involve replacement of some major components. I’m sure some people are waiting in the sidelines to buy a Garmin when WAAS is built-in so that they don’t have to pay again for an upgrade.

I’m also puzzled as to just what the WAAS is meant to achieve. While it improves accuracy, it’s still not good enough for precision approaches, and it can’t improve availability, since if the GPS is turned off, WAAS can’t function. So the only real benefit is integrity, since it can presumably detect errors in GPS data.

Can anyone out there enlighten me?

WAAS will be the greatest thing since sliced bread for IFR pilots, but only when it is approved for IFR. You will be able to make precision approaches because it will provide altitude correction to precise standards, which is currently lacking.

5

Good question. I’m sure (at least I hope) that someone out there really knows, but here’s my humble 2 cents. Yes, you do need a special receiver to take full advantage of WAAS. (There are some WAAS geosynchronous satellites that do look like extra GPS satellites to an ordinary receiver, so there is that small benefit.) But the specially formatted WAAS messages are only legible to a WAAS enabled receiver.

I’ve heard that once WAAS is cleared for IFR, it will allow “semi-precision” approaches with slightly higher minimums that CAT 1 (350’ instead of 200’, I think). It’s supposed to give a vertical and horizontal accuracy of 7 meters.

Garmin 430 claims to be WAAS compatible. If so, then your 430 should be giving you that accuracy as of today. Some of you owners out there might want to give them a call and ask. Is there a WAAS annunciator on the display, or any way to tell? Does the DOP number (dilution of position) that shows during powerup indicate anything?

Does anybody know what this actually means? Do you need a special GPS receiver to take advantage of this?

6

Does anybody know what this actually means? Do you need a special GPS receiver to take advantage of this? I know that the WAAS correction data is broadcast on the same frequencies as the GPS satellites, so the same hardware can presumably receive the signal, but it’s not clear (to me) if this just means the GPS receiver sees additional “virtual” satellites, or if the receiver needs extra capabilities to use it.

I’m also puzzled as to just what the WAAS is meant to achieve. While it improves accuracy, it’s still not good enough for precision approaches, and it can’t improve availability, since if the GPS is turned off, WAAS can’t function. So the only real benefit is integrity, since it can presumably detect errors in GPS data.

Can anyone out there enlighten me?

WAAS is a set of ground stations and geosynchronous satellites that provides error corrections and notification of failures over a wide area, hence “Wide Area Augmentation System”. It is needed because the basic GPS signal that is available to the public is neither accurate enough nor available enough for precision approaches. The big things WAAS brings is vertical accuracy and a fast (like 6 seconds) way to alert the pilot that the data from the satellites he is using is bad.

At the cockpit what this means is that today, if you have a WAAS capable receiver, it will do all off the wonderful things it is supposed to. You can take advantage of the improved information but you cannot use it as your only equipment for IFR. Of course if you have the WAAS capable receiver and don’t use it in conjunction with your LOC and glide slope for an ILS approach you are stupid. If you don’t use it for an NDB aproach, well enough said.

The reason it has not been certified is that the current test data showed that the signal from a satellite could have bad data and it might not be reported to the cockpit in the required time. The latest plan is to certify it for something like 300 and a mile until they get the bugs out of the integrity monitoring part so they can lower it to 200 and 1/2.

In a nutshell, use it but don’t bet your life on it. The GPS manufacturers can now build WAAS capable recievers without too much worry that just as they release one, the specs will change and make the new unit junk. It is a big deal to the FAA because they want to be able to say they are shutting off the ILS’s in their outyear budgets.

7

This is a disappointment. Stone says that WAAS provides “little additional accuracy over GPS now that Selective Availability has been discontinued”. Well, turning off SA improved vertical accuracy from 156 meters to 28 meters. But WAAS improves this still further to 7 meters. I’d call that significant, even before it’s approved for IFR.

Perhaps Garmin feels no “immediate pressure” due to lack of competition.

TSO C146 (Stand-Alone Airborne Navigation Equipment using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS)) is now released. We have begun to analyze exactly what it will take to incorporate WAAS into the GNS 430/530 products.

Recently, the FAA has announced that the WAAS signals are available for “VFR use”. Essentially, these are test signals which may be discontinued at any time without notice. Unfortunately, this provides no benefit to the users. (no IFR use, no enhanced integrity, little additional accuracy over GPS now that Selective Availability (SA) has been discontinued). As there is currently no immediate benefit to the user from WAAS (no precision approaches yet defined, and the aforementioned), we also do not see immediate pressure to offer this functionality in a hurry, but rather we will take our time and do it right.

We currently do not envision offering WAAS augmentation to our GNS 430/530 products until Initial Operational Capability (IOC) is declared on the system, which is currently scheduled for 2002.

As the precise details of what will be required to upgrade the GNS 430 to WAAS are currently unknown, pricing for this future upgrade has not yet been established. At a minimum, the unit will need to be returned to the factory to have new TSO markings applied. There will be a software upgrade required, and as of yet we do not know if a hardware upgrade will be necessary.

Thank you and best Regards,

Bill Stone
Avionics Product Manager
GARMIN International

8

This is a disappointment. Stone says that WAAS provides “little additional accuracy over GPS now that Selective Availability has been discontinued”. Well, turning off SA improved vertical accuracy from 156 meters to 28 meters. But WAAS improves this still further to 7 meters. I’d call that significant, even before it’s approved for IFR.

Perhaps Garmin feels no “immediate pressure” due to lack of competition.

TSO C146 (Stand-Alone Airborne Navigation Equipment using the Global Positioning System (GPS) Augmented by the Wide Area Augmentation System (WAAS)) is now released. We have begun to analyze exactly what it will take to incorporate WAAS into the GNS 430/530 products.

Recently, the FAA has announced that the WAAS signals are available for “VFR use”. Essentially, these are test signals which may be discontinued at any time without notice. Unfortunately, this provides no benefit to the users. (no IFR use, no enhanced integrity, little additional accuracy over GPS now that Selective Availability (SA) has been discontinued). As there is currently no immediate benefit to the user from WAAS (no precision approaches yet defined, and the aforementioned), we also do not see immediate pressure to offer this functionality in a hurry, but rather we will take our time and do it right.

We currently do not envision offering WAAS augmentation to our GNS 430/530 products until Initial Operational Capability (IOC) is declared on the system, which is currently scheduled for 2002.

As the precise details of what will be required to upgrade the GNS 430 to WAAS are currently unknown, pricing for this future upgrade has not yet been established. At a minimum, the unit will need to be returned to the factory to have new TSO markings applied. There will be a software upgrade required, and as of yet we do not know if a hardware upgrade will be necessary.

Thank you and best Regards,

Bill Stone
Avionics Product Manager
GARMIN International
The main purpose to have WAAS in the future is to increase the accuracy of GPS error down to a level that is comparible to an ILS or localizer. There has been considerable difficulty over the last few years getting this tp work correctly.When perfected, it will not change enroute navigation with GPS nor non-precision approach information at all as the PRESENT system already does this quite well and far better than the VOR’s. So the main utility to WAAS will be to provide precision GPS approachs and not much more. But this is a big deal when finally done as it will make VOR/ILS systems obsolete.
Why should Garmin be in a rush? There are NO approved GPS precision approaches now. It would be foolish for the company to add a system still not fully tested when it currently could not be used for anything. Better to wait until there is a use for it and a perfected system.