I certainly hope your IRS position is not several kilometers off from actual!
Well I hoped that too, but reality proved me wrong. Look through a day of data on a site like casperflights and see how often a B733 or F70 lands next to a runway according to their ADS-B data. These aircraft typically have no GPS receiver connected to the transponder and send out IRS data instead. Sometimes they are far off.
Departing aircraft sometimes seem to have the wrong runway set (e.g. L instead of R, or opposite threshold) when they start their takeoff roll, although this happens not so frequently.