Narrative:

I was inbound to osh for an event VFR in the low (1;800 MSL 90 KT) pattern. Having been holding with other traffic around rush lake due to outbound traffic congestion; I was inbound over the railroad tracks approaching fisk; was identified by ATC and acknowledged with a wing rock; and received ATC instructions to continue along the tracks for a right base for runway 9; departed fisk when directed. I subsequently received instructions to switch to the tower frequency. There was some discussion by ATC on the radio of there being more than one cessna in close proximity to fisk at the same time; but I came to the conclusion that the instructions were indeed directed at me. Inbound on the left base; the tower requested a deviation to the left and/or to slow down to accommodate inbound traffic on the left base; which I could see; so I turned and slowed as requested to follow the traffic in front. Shortly thereafter; about 0.5 NM from the approach end of runway 9; I heard a query from the tower asking about a 'flight of two cessnas'; was unsure if this question was directed at me; and grew concerned that there may be conflicting traffic. Then I heard another pilot state; somewhat anxiously; that he was 'slightly ahead and faster'; or something to that effect; looked to my right and was surprised to see at my 3 o'clock position another cessna flying parallel to my course and slightly faster; roughly one hundred feet away. At this point; since we were clearly converging on the same runway; since I had no prior arrangement with the other pilot to land as a flight; and since I had no experience in formation flight or formation landing; I considered that it would be unsafe to continue on final. Not receiving any instructions from the tower; and considering that a collision was potentially imminent; I made an immediate turn of 90 degrees to the left; maintaining altitude; and at the same time announced to the tower that I was the left cessna of the pair and that I was breaking off the approach to the left. I did not make this as a request and await instructions; since I was concerned that there was insufficient time in which to avoid a collision to do so; I was unsure of the state of mind and intentions of the other pilot; and visual observation of the area to the left as well as the information provided in the events NOTAM suggested that the area to the left would be clear. Subsequently; I continued a 360 turn back to the final approach course in 90 degree increments and was cleared to land on the white dot; and landed uneventfully. Reviewing the event afterward; three questions come to mind - how did the two of us inadvertently come to be at more or less the same location on short final; was my action to avoid a potential collision appropriate; and was rejoining the final after deviating the appropriate action? Since I had not previously observed the conflicting cessna; one possibility is that we had converged earlier; prior to or at fisk. I do recall some confusion on the radio at fisk but not the specific details. Alternatively; and I think more likely; the deviation to the left and request to slow for the left base traffic had perhaps allowed a cessna in trail to catch up; this seems likely; particularly if the following cessna did not have visual contact with my aircraft. Given the volume of traffic; I was maintaining a high state of alertness and vigilance; and was attempting to maintain a thorough visual scan; but it was largely concentrated forward; and I was not consciously looking for traffic that might be directly behind me and overtaking me; since I had not considered that possibility. A confounding factor seems to be the reliability of a pilot being sure that they have been identified by ATC over fisk. Even rocking one's wings in acknowledgment and having the rock confirmed; does not eliminate the possibility that another similar aircraft rocked their wings and was observed; with the result that two aircraft end up followingthe same instructions. On a previous visit to last years event I recall having no such confusion; even though conditions were less favorable in terms of visibility; the traffic volume was much lower and the time of day was mid-morning. At the time that I made the left turn away from final to avoid collision; I recall being surprised that I had not received an instruction from the tower to do so already; and this caused me some anxiety. The other alternative I considered was to continue straight ahead; stop the descent and climb; and go around; but having observed traffic in that direction earlier and being aware that runway 18/36 was also in use; this did not seem like a good choice; and I thought that had the tower wanted me to go around; they would have instructed me to do so. Further; had the tower not approved of my action to turn to the left; I expected that I would have received urgent instructions to do otherwise. After turning to the left; the possibilities were to leave the pattern and return to rippon or fisk; or to return to the final approach course. Assuming that the tower would expect me to rejoin and was instructed to continue the turn to rejoin; and no other traffic was pointed out. Hence in the absence of instructions to the contrary; it would seem that the decision to rejoin was correct. To prevent a similar situation; in future if in any doubt whatsoever about whether or not my aircraft is the one for which ATC instructions are intended; I would query on the radio; despite the admonition to avoid unnecessary radio calls in the NOTAM and despite the frequency being busy. Further; I might include the 6 o'clock position in my visual scan at regular intervals while on base and final; even though this is relatively awkward and potentially distracting from the attention needed to control the aircraft. Ideally ATC would identify the conflict earlier and issue explicit instructions; rather than presuming that two aircraft in close proximity are landing as a flight (which is I gather relatively unusual; even at this event); indeed; landing as a flight might better be prohibited to avoid this confusion.

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Original NASA ASRS Text

Title: A Cessna pilot on approach to OSH realized approaching final that two aircraft had taken the same landing clearance and so he was unintentionally flying a formation approach with another Cessna. He conducted an evasive maneuver and returned to land.

Narrative: I was inbound to OSH for an event VFR in the low (1;800 MSL 90 KT) pattern. Having been holding with other traffic around Rush Lake due to outbound traffic congestion; I was inbound over the railroad tracks approaching FISK; was identified by ATC and acknowledged with a wing rock; and received ATC instructions to continue along the tracks for a right base for Runway 9; departed FISK when directed. I subsequently received instructions to switch to the Tower frequency. There was some discussion by ATC on the radio of there being more than one Cessna in close proximity to FISK at the same time; but I came to the conclusion that the instructions were indeed directed at me. Inbound on the left base; the Tower requested a deviation to the left and/or to slow down to accommodate inbound traffic on the left base; which I could see; so I turned and slowed as requested to follow the traffic in front. Shortly thereafter; about 0.5 NM from the approach end of Runway 9; I heard a query from the Tower asking about a 'flight of two Cessnas'; was unsure if this question was directed at me; and grew concerned that there may be conflicting traffic. Then I heard another pilot state; somewhat anxiously; that he was 'slightly ahead and faster'; or something to that effect; looked to my right and was surprised to see at my 3 o'clock position another Cessna flying parallel to my course and slightly faster; roughly one hundred feet away. At this point; since we were clearly converging on the same runway; since I had no prior arrangement with the other pilot to land as a flight; and since I had no experience in formation flight or formation landing; I considered that it would be unsafe to continue on final. Not receiving any instructions from the Tower; and considering that a collision was potentially imminent; I made an immediate turn of 90 degrees to the left; maintaining altitude; and at the same time announced to the Tower that I was the left Cessna of the pair and that I was breaking off the approach to the left. I did not make this as a request and await instructions; since I was concerned that there was insufficient time in which to avoid a collision to do so; I was unsure of the state of mind and intentions of the other pilot; and visual observation of the area to the left as well as the information provided in the events NOTAM suggested that the area to the left would be clear. Subsequently; I continued a 360 turn back to the final approach course in 90 degree increments and was cleared to land on the white dot; and landed uneventfully. Reviewing the event afterward; three questions come to mind - how did the two of us inadvertently come to be at more or less the same location on short final; was my action to avoid a potential collision appropriate; and was rejoining the final after deviating the appropriate action? Since I had not previously observed the conflicting Cessna; one possibility is that we had converged earlier; prior to or at FISK. I do recall some confusion on the radio at FISK but not the specific details. Alternatively; and I think more likely; the deviation to the left and request to slow for the left base traffic had perhaps allowed a Cessna in trail to catch up; this seems likely; particularly if the following Cessna did not have visual contact with my aircraft. Given the volume of traffic; I was maintaining a high state of alertness and vigilance; and was attempting to maintain a thorough visual scan; but it was largely concentrated forward; and I was not consciously looking for traffic that might be directly behind me and overtaking me; since I had not considered that possibility. A confounding factor seems to be the reliability of a pilot being sure that they have been identified by ATC over FISK. Even rocking one's wings in acknowledgment and having the rock confirmed; does not eliminate the possibility that another similar aircraft rocked their wings and was observed; with the result that two aircraft end up followingthe same instructions. On a previous visit to last years event I recall having no such confusion; even though conditions were less favorable in terms of visibility; the traffic volume was much lower and the time of day was mid-morning. At the time that I made the left turn away from final to avoid collision; I recall being surprised that I had not received an instruction from the Tower to do so already; and this caused me some anxiety. The other alternative I considered was to continue straight ahead; stop the descent and climb; and go around; but having observed traffic in that direction earlier and being aware that Runway 18/36 was also in use; this did not seem like a good choice; and I thought that had the Tower wanted me to go around; they would have instructed me to do so. Further; had the Tower not approved of my action to turn to the left; I expected that I would have received urgent instructions to do otherwise. After turning to the left; the possibilities were to leave the pattern and return to Rippon or FISK; or to return to the final approach course. Assuming that the Tower would expect me to rejoin and was instructed to continue the turn to rejoin; and no other traffic was pointed out. Hence in the absence of instructions to the contrary; it would seem that the decision to rejoin was correct. To prevent a similar situation; in future if in any doubt whatsoever about whether or not my aircraft is the one for which ATC instructions are intended; I would query on the radio; despite the admonition to avoid unnecessary radio calls in the NOTAM and despite the frequency being busy. Further; I might include the 6 o'clock position in my visual scan at regular intervals while on base and final; even though this is relatively awkward and potentially distracting from the attention needed to control the aircraft. Ideally ATC would identify the conflict earlier and issue explicit instructions; rather than presuming that two aircraft in close proximity are landing as a flight (which is I gather relatively unusual; even at this event); indeed; landing as a flight might better be prohibited to avoid this confusion.

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.