Narrative:

Upon returning to land at chd, I radioed the control tower and advised that I was over memorial airfield (L07) and inbound for a touch-and-go landing. The controller acknowledged my request and directed me to make right traffic for runway 22R and to report entering the downwind. Just prior to reaching the downwind leg, I noticed a piper twin comanche that appeared to be approaching (or already on) a left downwind for runway 4L. The twin comanche was at my approximately altitude (2200 ft MSL) and appeared to be traveling at an unreasonably high rate of speed. The 2 aircraft were separated by less than 100 ft vertically and by less than 3000 ft laterally. When the tower controller requested that I report my position, I replied that I had just entered a right downwind for runway 22R and that I had been cut off by the twin comanche. The tower controller then advised the twin comanche pilot that he was not in the correct traffic pattern, and to enter the correct pattern immediately. Just prior to turning base for runway 22R (and with a clearance to land on runway 22R), I observed the twin comanche pass underneath my aircraft at an unreasonably high rate of speed. The 2 aircraft were separated by less than 100 ft vertically and by less than 50 ft laterally. I immediately took evasive action to avoid colliding with the twin comanche. Upon observing this, the tower controller canceled my landing clearance and cleared the twin comanche to land ahead of me. The remainder of my flight was completed without incident. Upon returning home after the flight, I called the chd tower and requested the registration number of the twin comanche. I received that information, and was advised that the pilot of the twin comanche had been instructed to 'call the tower' upon landing. I later filed an near midair collision report with the prescott FSS.

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Original NASA ASRS Text

Title: A VERY LOW TIME PLT, CLRED FOR LNDG AT CHD, WAS TWICE CUT OFF BY A TWIN COMANCHE. HE RPTED AN NMAC WITH PRESCOTT FSS.

Narrative: UPON RETURNING TO LAND AT CHD, I RADIOED THE CTL TWR AND ADVISED THAT I WAS OVER MEMORIAL AIRFIELD (L07) AND INBOUND FOR A TOUCH-AND-GO LNDG. THE CTLR ACKNOWLEDGED MY REQUEST AND DIRECTED ME TO MAKE R TFC FOR RWY 22R AND TO RPT ENTERING THE DOWNWIND. JUST PRIOR TO REACHING THE DOWNWIND LEG, I NOTICED A PIPER TWIN COMANCHE THAT APPEARED TO BE APCHING (OR ALREADY ON) A L DOWNWIND FOR RWY 4L. THE TWIN COMANCHE WAS AT MY APPROX ALT (2200 FT MSL) AND APPEARED TO BE TRAVELING AT AN UNREASONABLY HIGH RATE OF SPD. THE 2 ACFT WERE SEPARATED BY LESS THAN 100 FT VERTLY AND BY LESS THAN 3000 FT LATERALLY. WHEN THE TWR CTLR REQUESTED THAT I RPT MY POS, I REPLIED THAT I HAD JUST ENTERED A R DOWNWIND FOR RWY 22R AND THAT I HAD BEEN CUT OFF BY THE TWIN COMANCHE. THE TWR CTLR THEN ADVISED THE TWIN COMANCHE PLT THAT HE WAS NOT IN THE CORRECT TFC PATTERN, AND TO ENTER THE CORRECT PATTERN IMMEDIATELY. JUST PRIOR TO TURNING BASE FOR RWY 22R (AND WITH A CLRNC TO LAND ON RWY 22R), I OBSERVED THE TWIN COMANCHE PASS UNDERNEATH MY ACFT AT AN UNREASONABLY HIGH RATE OF SPD. THE 2 ACFT WERE SEPARATED BY LESS THAN 100 FT VERTLY AND BY LESS THAN 50 FT LATERALLY. I IMMEDIATELY TOOK EVASIVE ACTION TO AVOID COLLIDING WITH THE TWIN COMANCHE. UPON OBSERVING THIS, THE TWR CTLR CANCELED MY LNDG CLRNC AND CLRED THE TWIN COMANCHE TO LAND AHEAD OF ME. THE REMAINDER OF MY FLT WAS COMPLETED WITHOUT INCIDENT. UPON RETURNING HOME AFTER THE FLT, I CALLED THE CHD TWR AND REQUESTED THE REGISTRATION NUMBER OF THE TWIN COMANCHE. I RECEIVED THAT INFO, AND WAS ADVISED THAT THE PLT OF THE TWIN COMANCHE HAD BEEN INSTRUCTED TO 'CALL THE TWR' UPON LNDG. I LATER FILED AN NMAC RPT WITH THE PRESCOTT FSS.

Data retrieved from NASA's ASRS site as of July 2007 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.