Narrative:

I was on an IFR flight plan. My flight plan as assigned had a dogleg in it; at abc VOR; then direct to my destination. Just after abc VOR; I was handed off to approach at 6000 ft. I requested direct to the airport. I heard that I was cleared to direct after leaving 7000 ft. I read back that I was cleared direct with my call sign; and that I was leaving 6000 ft. (I probably used my abbreviated call sign; rather than my full call sign.) shortly; I was told by ATC that I should immediately climb to 6000 ft and to deviate 30 degrees to the right. I heard another plane told to deviate 30 degrees to the left. Although I certainly thought that I heard the correct call sign; listening to other planes on the frequency; there was another plane on the frequency that had a similar call sign to mine; also going to my destination. I would presume that either I misheard the clearance; and assumed that the clearance for the other similar call sign was for me; or that ATC had gotten my call sign incorrect and gave the wrong call sign to me. Some contributing factors: 1) two or three times previously in this flight; other ATC controllers had gotten my call sign wrong. I had corrected them on this; and they acknowledged their errors. This probably lulled me into thinking that controllers were having trouble for some reason with my call sign. (Perhaps the flight strip was incorrect.) 2) there are several planes headed to my destination. The weather was very good; and there was significant traffic.3) I did hear that the clearance was a bit strange. I was only at 6000 ft but was cleared direct on leaving 7000 ft. I could have confirmed that this clearance was for me and that I could leave 6000 ft immediately.

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Original NASA ASRS Text

Title: An IFR single pilot had an altitude deviation because of a hearback/readback error. Similar sounding call signs and failure to use complete aircraft call signs for communications caused the pilot to take another aircraft's clearance.

Narrative: I was on an IFR flight plan. My flight plan as assigned had a dogleg in it; at ABC VOR; then direct to my destination. Just after ABC VOR; I was handed off to Approach at 6000 FT. I requested direct to the airport. I heard that I was cleared to direct after leaving 7000 FT. I read back that I was cleared direct with my call sign; and that I was leaving 6000 FT. (I probably used my abbreviated call sign; rather than my full call sign.) Shortly; I was told by ATC that I should immediately climb to 6000 FT and to deviate 30 degrees to the right. I heard another plane told to deviate 30 degrees to the left. Although I certainly thought that I heard the correct call sign; listening to other planes on the frequency; there was another plane on the frequency that had a similar call sign to mine; also going to my destination. I would presume that either I misheard the clearance; and assumed that the clearance for the other similar call sign was for me; or that ATC had gotten my call sign incorrect and gave the wrong call sign to me. Some contributing factors: 1) Two or three times previously in this flight; other ATC Controllers had gotten my call sign wrong. I had corrected them on this; and they acknowledged their errors. This probably lulled me into thinking that controllers were having trouble for some reason with my call sign. (Perhaps the flight strip was incorrect.) 2) There are several planes headed to my destination. The weather was very good; and there was significant traffic.3) I did hear that the clearance was a bit strange. I was only at 6000 FT but was cleared direct on leaving 7000 FT. I could have confirmed that this clearance was for me and that I could leave 6000 FT immediately.

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.