Taxi plate won't show actual location aircraft

[mdragon]

I've been having this issue for months. Wondering if anybody knows the cause. I use Seattle avionics for airport taxi information. Lately, it shows the magenta airplane that indicates location significantly off from actual location when the taxi diagrams pulled up. Sometimes a mile away from where the airplane actually is. Despite updating the Seattle avionics database several times, the problem persists. Any ideas?

GPS shows a very specific latitude and longitude and appears to be properly synced with satellites when this occurs.

 

[airguy]

Try other airports - it could be an error on just the one plate, or it could be that your GPS is giving a false location.

 

[swatson999]

Most likely the plate. False positions for GPS are usually due to cycle slips, such as a millisecond interrupt slip which will cause a 300 km sudden jump in position followed by a return to the correct location. The GPS solution is pretty robust and if it were wrong on a plate, it'd likely be wrong on all mapping.

My guess...the georeferencing data on the plate is bad. It happens.