Narrative:

On a training flight we had crossed gep VOR 2;500 ft heading toward ane airport where we had been training earlier in the flight. We were in communication with the tower at ane about 8 NM west of ane. We were instructed to continue for straight-in to runway 9 which we had in sight. Other aircraft were on the frequency but no other aircraft were in our area. We caught sight of an aircraft north of us and much lower than us and appeared to be within a couple hundred feet from the trees heading north. I considered them 'no factor' but asked the tower if they had that aircraft and they replied no. We proceeded for the visual approach to runway 9 and just after leaving the pattern altitude about 1;800 ft the student in the left seat caught an aircraft out his window just below us. It appeared to be the same aircraft we had identified just a couple minutes earlier. He was heading slightly southeastward. They were pushing us off our final approach to runway 9. As we corrected to the southeast to avoid this aircraft I told tower we had an aircraft out our left window within probably 200 ft. He did not have him on a transponder and was able to visually see him with field glasses out the tower window. The tower at ane tried several times to call this aircraft with no joy. We were faster than this aircraft and got ahead of them and made our way back to our visual approach. This unidentified aircraft then proceeded southeast bound conflicting with an aircraft on right down wind for runway 9. When this event happened we were 2 to 2.5 miles from runway 9 threshold within class D airspace. No further event occurred. This unidentified aircraft appeared to be a homebuilt (ultralight?) with an enclosed cabin that looked as if it seated two. It looked similar to a flying egg.

Related reports:

Google
 

Original NASA ASRS Text

Title: An Instructor pilot reported taking evasive action to avoid an apparently home built aircraft in the ANE traffic pattern.

Narrative: On a training flight we had crossed GEP VOR 2;500 FT heading toward ANE airport where we had been training earlier in the flight. We were in communication with the Tower at ANE about 8 NM west of ANE. We were instructed to continue for straight-in to Runway 9 which we had in sight. Other aircraft were on the frequency but no other aircraft were in our area. We caught sight of an aircraft north of us and much lower than us and appeared to be within a couple hundred feet from the trees heading north. I considered them 'no factor' but asked the Tower if they had that aircraft and they replied no. We proceeded for the visual approach to Runway 9 and just after leaving the pattern altitude about 1;800 FT the student in the left seat caught an aircraft out his window just below us. It appeared to be the same aircraft we had identified just a couple minutes earlier. He was heading slightly southeastward. They were pushing us off our final approach to Runway 9. As we corrected to the southeast to avoid this aircraft I told Tower we had an aircraft out our left window within probably 200 FT. He did not have him on a transponder and was able to visually see him with field glasses out the Tower window. The Tower at ANE tried several times to call this aircraft with no joy. We were faster than this aircraft and got ahead of them and made our way back to our visual approach. This unidentified aircraft then proceeded southeast bound conflicting with an aircraft on right down wind for Runway 9. When this event happened we were 2 to 2.5 miles from Runway 9 threshold within Class D airspace. No further event occurred. This unidentified aircraft appeared to be a homebuilt (ultralight?) with an enclosed cabin that looked as if it seated two. It looked similar to a flying egg.

Data retrieved from NASA's ASRS site as of April 2012 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.