After doing some maneuvers to get a student familiar with a C172, we decided to go to a nearby airport for landing practice. We have been to this airport many times before but always arriving from a different direction. I was also showing him how to use the Garmin 430 and walked him through the steps to enter the airport as a Direct to. With that done the magenta line was showing about a 5º heading to the left. Hmm, I see the runway dead ahead. I started talking about the winds may be stronger and causing us to crab some and I fiddle with North up vs Track up as we continue to the runway. We were about 10 miles out when we started. Its been about 4 minutes now and tower calls and asks if we are headed to their airport as we are 3 miles north of them. HUH?
Something is off I finally concede and look towards the area the GPS has been pointing all along. Whoops, yes I say we are as I have the student make an immediate left turn and get lined up with the correct runway. These 2 airports are only 5 miles apart and have similarly orientated runways on 10º apart.
The lesson we both learned is to pay attention and look outside as I did see a different runway layout from the airport we should have been heading to, but it didn’t rise to the level of triggering an alert in my brain. Also the magenta line is usually right as long as its correctly programmed which I checked and it was. So don’t let a runway in sight cause you to deviate from where you really want to go.