Diamond da-20 pilot reported a near-mid-air-collision while entering the traffic pattern of a non-to...

Narrative:

Approaching into traffic pattern; all appropriate position radio calls were made. Just before turning onto base leg; I looked up to see a [single engine beechcraft] just above me and to my left. He had overtaken me from behind but had not seen me either visually or on his TCAS. No evasive action was required to maintain separation; but I gave way to him and turned to my right; level altitude. I glanced at my radio to discover I have been making all my radio calls on 122.7 instead of 122.8; which is ZZZ's CTAF. 122.7 is the CTAF for ZZZ1; where we had just come from. 122.8 was in my stand-by freq slot. I switched over to 122.8 and communicated with the [other aircraft]. He admitted that he never saw me as I was below him and slightly to his right; and nothing appeared on his TCAS. He also mentioned that he never heard my radio calls. I confessed that I was making radio calls; but on the wrong frequency.both aircraft landed without incident; and no evasive maneuvers were required by either aircraft. However; as stated; I gave way to the [other aircraft] by making a right 360 and re-entered the pattern on the left 45; ensuring I was on the correct radio frequency.I feel both pilots could have broken the chain of events. I; as the pilot of the diamond could have broken the chain of events simply by having been on the correct radio frequency. Having been ahead and below the [other aircraft]; it would not have been possible to have seen the plane overtake us on the downwind leg. I entered the traffic pattern on the 45 at pattern altitude and was able to complete my downwind leg and did not see the aircraft overtake us. Had I heard the [other] pilot's radio calls; I could have easily known where to look for him and maintain situational awareness. I never saw the [other aircraft] on downwind at any time.the [other] pilot could have broken the chain of events if his focus was looking for traffic. A [single engine beechcraft] in the pattern is flying at higher air speeds than a diamond da-20; so it can be surmised that the pilot had time to see the da-20 enter the downwind from the 45; as he would have had to been on crosswind or just starting his downwind at the time. The [other] pilot admitted he didn't see me on his TCAS; and never saw me visually during the entire event. His plane did not appear on my traffic information service.

Original NASA ASRS Text

Title: Diamond DA-20 pilot reported a near-mid-air-collision while entering the traffic pattern of a non-towered airport. He discovered that his radio had not been tuned to the correct CTAF frequency.

Narrative: Approaching into traffic pattern; all appropriate position radio calls were made. Just before turning onto Base leg; I looked up to see a [single engine Beechcraft] just above me and to my left. He had overtaken me from behind but had not seen me either visually or on his TCAS. No evasive action was required to maintain separation; but I gave way to him and turned to my right; level altitude. I glanced at my radio to discover I have been making all my radio calls on 122.7 instead of 122.8; which is ZZZ's CTAF. 122.7 is the CTAF for ZZZ1; where we had just come from. 122.8 was in my stand-by freq slot. I switched over to 122.8 and communicated with the [other aircraft]. He admitted that he never saw me as I was below him and slightly to his right; and nothing appeared on his TCAS. He also mentioned that he never heard my radio calls. I confessed that I was making radio calls; but on the wrong frequency.Both aircraft landed without incident; and no evasive maneuvers were required by either aircraft. However; as stated; I gave way to the [other aircraft] by making a right 360 and re-entered the pattern on the left 45; ensuring I was on the correct radio frequency.I feel both pilots could have broken the chain of events. I; as the pilot of the Diamond could have broken the chain of events simply by having been on the correct radio frequency. Having been ahead and below the [other aircraft]; it would not have been possible to have seen the plane overtake us on the downwind leg. I entered the traffic pattern on the 45 at pattern altitude and was able to complete my downwind leg and did not see the aircraft overtake us. Had I heard the [other] pilot's radio calls; I could have easily known where to look for him and maintain situational awareness. I never saw the [other aircraft] on downwind at any time.The [other] pilot could have broken the chain of events if his focus was looking for traffic. A [single engine Beechcraft] in the pattern is flying at higher air speeds than a Diamond DA-20; so it can be surmised that the pilot had time to see the DA-20 enter the downwind from the 45; as he would have had to been on crosswind or just starting his downwind at the time. The [other] pilot admitted he didn't see me on his TCAS; and never saw me visually during the entire event. His plane did not appear on my Traffic Information Service.

Data retrieved from NASA's ASRS site 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.

Attributes
ACN	1296359
Time
Date	201509
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	DA20-A1 Katana
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	None
Person 1
Function	Instructor Pilot Flying
Qualification	Flight Crew Commercial Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 120 Flight Crew Total 575 Flight Crew Type 50
Events
Anomaly	Aircraft Equipment Problem Less Severe Conflict NMAC Deviation - Procedural Published Material / Policy
Miss Distance	Horizontal 150 Vertical 40

Diamond da-20 pilot reported a near-mid-air-collision while entering the traffic pattern of a non-towered airport. He discovered that his radio had not been tuned to the correct CTAF frequency.