Some areas are harder to triangulate as the satellites are close to the horizon (north & south polar areas).
When you are in a dense city triangulation can be tough as well as the line of sight can be blocked by large buildings.
This is why a hybrid solution using satellites, Cell towers & WiFi AP's is used to improve the accuracy of global positioning.
Also remember the public GPS signals are slightly phased over the military GPS signals which can do ionospheric correction (8 meters/26 feet or more near the poles). Here's the US Governments web site that gets into all of this: GPS Accuracy
With that said, compare your iPad to another iPad (or other like GPS device) to see if the GPS services are damaged. If they both react the same the issue is your location.