Narrative:

This was an instructional flight and we were working on pilotage and dead reckoning navigation. Our destination was orange county (mgj) which is 7 NM to the west of stewart (swf). I had mentioned to my student that if he conducted the flight to my satisfaction I would sign him off for solo cross country privileges. He was doing well with navigation as well as overall operation of the flight. As a result; I relaxed my vigilance. My student started having difficulties approximately 15 miles south of mgj. The current ny sectional chart shows a prominent lake approximately 9 NM southwest of mgj that he had planned to use as a visual checkpoint. He was not able to locate the lake; and when I tried looking for it I couldn't see it either. Eventually I spotted a lake east of the expected location and concluded that was the lake we were looking for even though it didn't seem to be exactly the right shape and size. In any case I wasn't concerned because I could see hangars in front of us in the approximate direction and distance that I expected mgj to be. In addition to the confusion about the visual landmark; my student was having a hard time in managing the radios to obtain the ASOS weather at mgj as well as tune in the CTAF frequency. Since I had planned to sign him off after today's flights; I was monitoring his operation of the radios more closely than usual. Again; I was not overly concerned about the navigation as I could see airport buildings and other cues getting closer in the approximate location I expected. By the time my student had sorted out the radios; we were within a few NM of the airport I had seen. My student saw it as well and as we approached the airport; I took a quick look at mgj's airport diagram. It has two runways 26-8 and 21-3. Since I had been extremely rushed during the last portion of the flight; I did not notice that the airport we were almost directly over did not have the proper runway layout. We crossed over stewart (swf) at 2;000 MSL; and my student entered what he thought was a right hand pattern for runway 21 at mgj when he was really on a right downwind for runway 27 at swf. I could see the indications on his dg were not consistent with runway 21 but I let him continue since I wanted to see how far he would go before realizing his mistake. Unfortunately; I was making a mistake as well since I thought he was on downwind for runway 26 at mgj; and the dg indications supported that conclusion. On short final I asked him to go-around and we climbed back up to 2;000 ft for another pattern entry. He again set himself up on a right downwind for runway 27 thinking it was runway 21 at mgj. This time I was much more aware of the inconsistent dg indications and other cues and realized we had been operating in swf class D airspace without communicating with the tower. Shortly after realizing the error I radioed swf tower and explained the circumstances on the telephone after landing. Summary of factors contributing to the situation: 1. Lake on chart to be used as a visual landmark not visible on the ground. 2. Lack of vigilance on my part during the first two-thirds of the flight since student was doing very well. This allowed us to end up east of our intended track heading toward swf. 3. Overly engrossed in student's operation and management of the radios during the last third of the flight. 4. Seeing an airport environment 10 - 15 miles out and assuming it's the airport of destination since up to that point the navigation exercise had gone well. 5. Mgj and swf having similar runways (26 at mgj and 27 at swf). 6. Not having been to mgj in the past. Note: I flew the same route with my student a few days later. The lake that shows on the ny sectional on a bearing of 225 degrees magnetic and 9.5 NM from mgj was not visible from the air. After the flight I checked an older sectional (79th edition effective 7 may 2009) and the lake is not on it. I wonder if the lake is indicated on newer sectionals in error.

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Original NASA ASRS Text

Title: An instructor pilot discovered the New York Sectional map depicted a lake about nine miles bearing about 225 degrees from MGJ; but the lake cannot be seen from air and presents a false visual navigation landmark.

Narrative: This was an instructional flight and we were working on pilotage and dead reckoning navigation. Our destination was Orange County (MGJ) which is 7 NM to the west of Stewart (SWF). I had mentioned to my student that if he conducted the flight to my satisfaction I would sign him off for solo cross country privileges. He was doing well with navigation as well as overall operation of the flight. As a result; I relaxed my vigilance. My student started having difficulties approximately 15 miles south of MGJ. The current NY sectional chart shows a prominent lake approximately 9 NM southwest of MGJ that he had planned to use as a visual checkpoint. He was not able to locate the lake; and when I tried looking for it I couldn't see it either. Eventually I spotted a lake east of the expected location and concluded that was the lake we were looking for even though it didn't seem to be exactly the right shape and size. In any case I wasn't concerned because I could see hangars in front of us in the approximate direction and distance that I expected MGJ to be. In addition to the confusion about the visual landmark; my student was having a hard time in managing the radios to obtain the ASOS weather at MGJ as well as tune in the CTAF frequency. Since I had planned to sign him off after today's flights; I was monitoring his operation of the radios more closely than usual. Again; I was not overly concerned about the navigation as I could see airport buildings and other cues getting closer in the approximate location I expected. By the time my student had sorted out the radios; we were within a few NM of the airport I had seen. My student saw it as well and as we approached the airport; I took a quick look at MGJ's airport diagram. It has two runways 26-8 and 21-3. Since I had been extremely rushed during the last portion of the flight; I did not notice that the airport we were almost directly over did not have the proper runway layout. We crossed over Stewart (SWF) at 2;000 MSL; and my student entered what he thought was a right hand pattern for Runway 21 at MGJ when he was really on a right downwind for Runway 27 at SWF. I could see the indications on his DG were not consistent with Runway 21 but I let him continue since I wanted to see how far he would go before realizing his mistake. Unfortunately; I was making a mistake as well since I thought he was on downwind for Runway 26 at MGJ; and the DG indications supported that conclusion. On short final I asked him to go-around and we climbed back up to 2;000 FT for another pattern entry. He again set himself up on a right downwind for Runway 27 thinking it was Runway 21 at MGJ. This time I was much more aware of the inconsistent DG indications and other cues and realized we had been operating in SWF Class D airspace without communicating with the Tower. Shortly after realizing the error I radioed SWF Tower and explained the circumstances on the telephone after landing. Summary of factors contributing to the situation: 1. Lake on chart to be used as a visual landmark not visible on the ground. 2. Lack of vigilance on my part during the first two-thirds of the flight since student was doing very well. This allowed us to end up east of our intended track heading toward SWF. 3. Overly engrossed in student's operation and management of the radios during the last third of the flight. 4. Seeing an airport environment 10 - 15 miles out and assuming it's the airport of destination since up to that point the navigation exercise had gone well. 5. MGJ and SWF having similar runways (26 at MGJ and 27 at SWF). 6. Not having been to MGJ in the past. Note: I flew the same route with my student a few days later. The lake that shows on the NY sectional on a bearing of 225 degrees magnetic and 9.5 NM from MGJ was not visible from the air. After the flight I checked an older sectional (79th edition effective 7 May 2009) and the lake is not on it. I wonder if the lake is indicated on newer sectionals in error.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.