What type of altitude input is required for TAWS?
Most TAWS installations require only uncorrected barometric pressure altitude information from an existing encoding altimeter. This altitude information is combined together with the altitude dervied from the connected GPS to provide accurate altitude information. This combination of pressure altitude and GPS altitude is called “Geometric Altitude” which is less susceptible to errors or malfunctions from normal altimeter systems.

What type of altitude input is required for TAWS?
Most TAWS installations require only uncorrected barometric pressure altitude information from an existing encoding altimeter. This altitude information is combined together with the altitude dervied from the connected GPS to provide accurate altitude information. This combination of pressure altitude and GPS altitude is called “Geometric Altitude” which is less susceptible to errors or malfunctions from normal altimeter systems.Most TAWS installations require only uncorrected barometric pressure altitude information from an existing encoding altimeter. This altitude information is combined together with the altitude dervied from the connected GPS to provide accurate altitude information. This combination of pressure altitude and GPS altitude is called “Geometric Altitude” which is less susceptible to errors or malfunctions from normal altimeter systems.

Is the GPS Altitude Accurate?
Now that SA (Selective Availability) has been turned off, the general answer to this is Yes. GPS altitude is at least as accurate as the reading from a barometric altimeter. However, to determine altitude a GPS MUST be receiving information from at least three satellites and the more it is tracking, the better. If you want more information on this subject, there have been NUMEROUS postings on the rec.aviation.soaring and sci.geo.satellite-nav newsgroups. I encourage you to check them out.

When starting FsXPand, I am unable to taxi away. What is happening?
There was a bug in version 4.3 causing the parking brakes to lock. If this behaviour is still present in version 5.1, please check if you have assigned brakes to a analog channel and wired it up reversely (a common error). You should be able to taxi when the brakes are fully down. Reverse the wiring in that case.

When starting FsXPand, I am unable to taxi away. What is happening?
There was a bug in version 4.3 causing the parking brakes to lock. If this behaviour is still present in version 5.1, please check if you have assigned brakes to a analog channel and wired it up reversely (a common error). You should be able to taxi when the brakes are fully down. Reverse the wiring in that case. After resizing the panel, the tics in my fuel gauges are gone, and there are no digits anymore. There is a bug causing this to disappear.Now that SA (Selective Availability) has been turned off, the general answer to this is Yes. GPS altitude is at least as accurate as the reading from a barometric altimeter. However, to determine altitude a GPS MUST be receiving information from at least three satellites and the more it is tracking, the better. If you want more information on this subject, there have been NUMEROUS postings on the rec.aviation.soaring and sci.geo.

How accurate are the heights or depths?
The aircraft vertical position was determined using the navigational positioning equipment on the aircraft, which were radar altimeter and barometric altimeter. Radar altimeters are estimated to have an error of 2-5% of the altitude (Richard Hansen, PRJ, Inc., written communication). Barometric altimeters are quite accurate, but are typically operated in an uncorrected mode.Some high-end GPS devices offer barometric pressure to obtain a measurement for elevation when signal reception is not very good. The result is that you will have a smoother elevation profile in the Dashboard and Map Player. Without an altimeter, the GPS assumes your elevation is not changing when the signal goes bad. This results in a blocky elevation profile.