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Dynon released v5.1 of software today for all current EFIS units (D10A, D100, D180), and version 1.0 for the new D6 and D60. These versions of software add a feature we are very excited about: GPS Assist.
As most Dynon customers know, the Attitude system in Dynon EFIS units use airspeed to help it calculate which way is up™. Dynon has always believed that the use of airspeed gives us superior attitude performance, due to the fact that we measure airspeed directly, instead of estimating it. Airspeed is a crucial number inside any AHRS unit, but there are multiple ways to measure or estimate it. No estimate is ever perfect, so direct measurement can really help performance, especially in aircraft that have high horsepower to weight ratios. One advantage of direct measurement is reflected in the fact that we can be powered up while in flight and only need a few seconds to get aligned, whereas other systems can need minutes on the ground, motionless, in order to perform correctly.
The use of airspeed does, of course, carry one large caveat, which is that attitude performance degrades if a pitot becomes blocked by ice or another obstruction. While this is a rare situation in a properly equipped IFR aircraft, it is clearly not one that you ever want to encounter.
Dynon has been working hard to change this situation. We have considered a lot of different solutions, and we continue to believe that direct measurement of airspeed gives us superior AHRS performance. Given this, we decided the solution was to supplement airspeed with GPS data when it was warranted. GPS data is particularly nice in that it is commonly available, and it is easy to know when the data is valid and when it is not. We feel we’re in good company with this method. Garmin uses GPS as a primary source in the G1000 AHRS, and if GPS fails they switch to pitot and magnetometer. They require “external” aiding in the same way that we do.
This GPS assist system has been thoroughly tested, and has been flown heads down for hours on end with only GPS as the reference. Based on our testing, we believe all IFR maneuvers (and even more aggressive ones than that) can be safely and accurately flown when using GPS assist. We think this is a great addition to the Dynon EFIS line and are excited to have this available for all current EFIS systems.
To use GPS assist, you must have GPS hooked up to your EFIS and properly configured. Many of you already have this connection made in order to use the HSI, autopilot, or other functions. If you do, there’s nothing you need to do besides updating to v5.1 in order to use GPS assist. If you do not have GPS hooked up yet, instructions on how to do so can be found in the EFIS install manual. The latest manuals can always be found at http://docs.dynonavionics.com
The addition of GPS assist gives the EFIS some new behaviors:
If GPS data is available, it will be used when the system considers it to be better than airspeed. This will be indicated on the screen with a magenta "GPS ASSIST" and the GPS ground speed will pop up below the IAS number, labeled "Gspd". This is also a great warning that your IAS number is probably inaccurate.
If GPS data fails while it was in use (ie when pitot had already failed and then GPS fails), "CROSS CHECK ATTITUDE" will appear on the screen. You can continue to use the attitude as a reference, but please be vigilant in cross checking the attitude against heading, turn rate, VSI, etc.
If no GPS is hooked to the system, no changes in behavior occur.
Many old annunciations that were "black and white" attitude screens now are annunciated with text below the aircraft icon.
If you wish to manually test GPS assist, the easiest way is to give your EFIS zero airspeed by venting the pitot line to the atmosphere in the cabin. Be aware that if the EFIS is your only IAS gauge in the plane, you will now have NO IAS gauge. Please fly safely. If you have backup steam gauges or an IAS gauge, please make sure you block the disconnected pitot line so they continue to work.
As most Dynon customers know, the Attitude system in Dynon EFIS units use airspeed to help it calculate which way is up™. Dynon has always believed that the use of airspeed gives us superior attitude performance, due to the fact that we measure airspeed directly, instead of estimating it. Airspeed is a crucial number inside any AHRS unit, but there are multiple ways to measure or estimate it. No estimate is ever perfect, so direct measurement can really help performance, especially in aircraft that have high horsepower to weight ratios. One advantage of direct measurement is reflected in the fact that we can be powered up while in flight and only need a few seconds to get aligned, whereas other systems can need minutes on the ground, motionless, in order to perform correctly.
The use of airspeed does, of course, carry one large caveat, which is that attitude performance degrades if a pitot becomes blocked by ice or another obstruction. While this is a rare situation in a properly equipped IFR aircraft, it is clearly not one that you ever want to encounter.
Dynon has been working hard to change this situation. We have considered a lot of different solutions, and we continue to believe that direct measurement of airspeed gives us superior AHRS performance. Given this, we decided the solution was to supplement airspeed with GPS data when it was warranted. GPS data is particularly nice in that it is commonly available, and it is easy to know when the data is valid and when it is not. We feel we’re in good company with this method. Garmin uses GPS as a primary source in the G1000 AHRS, and if GPS fails they switch to pitot and magnetometer. They require “external” aiding in the same way that we do.
This GPS assist system has been thoroughly tested, and has been flown heads down for hours on end with only GPS as the reference. Based on our testing, we believe all IFR maneuvers (and even more aggressive ones than that) can be safely and accurately flown when using GPS assist. We think this is a great addition to the Dynon EFIS line and are excited to have this available for all current EFIS systems.
To use GPS assist, you must have GPS hooked up to your EFIS and properly configured. Many of you already have this connection made in order to use the HSI, autopilot, or other functions. If you do, there’s nothing you need to do besides updating to v5.1 in order to use GPS assist. If you do not have GPS hooked up yet, instructions on how to do so can be found in the EFIS install manual. The latest manuals can always be found at http://docs.dynonavionics.com
The addition of GPS assist gives the EFIS some new behaviors:
If GPS data is available, it will be used when the system considers it to be better than airspeed. This will be indicated on the screen with a magenta "GPS ASSIST" and the GPS ground speed will pop up below the IAS number, labeled "Gspd". This is also a great warning that your IAS number is probably inaccurate.
If GPS data fails while it was in use (ie when pitot had already failed and then GPS fails), "CROSS CHECK ATTITUDE" will appear on the screen. You can continue to use the attitude as a reference, but please be vigilant in cross checking the attitude against heading, turn rate, VSI, etc.
If no GPS is hooked to the system, no changes in behavior occur.
Many old annunciations that were "black and white" attitude screens now are annunciated with text below the aircraft icon.
If you wish to manually test GPS assist, the easiest way is to give your EFIS zero airspeed by venting the pitot line to the atmosphere in the cabin. Be aware that if the EFIS is your only IAS gauge in the plane, you will now have NO IAS gauge. Please fly safely. If you have backup steam gauges or an IAS gauge, please make sure you block the disconnected pitot line so they continue to work.
