Narrative:

Air carrier X took off from cuidad, or, en route to hermosillo, mexico. An ATR had taken off ahead of us also inbound to hermosillo (hmo). The ATR was at all times at least 13 mi ahead of us, according to position reports (non radar environment). Upon arrival into hmo, WX was IMC, approach cleared X and the ATR for the same arrival and approach into hermosillo. X started the published arrival and approach. We followed our company procedures and instrument procedures, we executed the arrival and approach and landing at hermosillo without incident. When X was clearing the runway, we noticed an ATR go overhead on the missed. We had never seen the ATR throughout the arrival or approach. In fact, we weren't even certain that the ATR on the miss was the same ATR we were following. While we were on the ramp, I monitored tower frequency, I heard the ATR pilot ask the tower what had happened. He said he had to use evasive action to avoid hitting aircraft on final approach. In spanish, I heard the tower ask the ATR pilot to come up to the tower and that they would explain what had happened. I realized it was the same ATR we were following, confused as to what had happened and how and when we had passed the ATR on the approach. I proceeded to go to the tower. When both pilots arrived at the tower, approach control told us that he shouldn't have cleared us both for the same arrival, but that he thought, based on our position reports, that we had adequate separation. He also said that he didn't think X had executed the arrival as published, the ATR pilot agreed that X hadn't executed the published arrival. I (captain of X) told them that we had executed the published arrival and approach and hadn't deviated from any clearance. We discussed several possible factors that could have caused this incident, including didn't slow down enough on the arrival and ATR slowed down too much. Ultimately, we all agreed that approach control should not clear 2 aircraft for the same arrival or approach in a non radar environment. Supplemental information from acn 296481: ATR took off before us, also headed to hmo, mexico. Hmo approach told us that the ATR was 13 DME ahead of us. All communication with the ATR and all other aircraft were in spanish. We were cleared for the miura 1 arrival to runway 23 hmo. The miura DME consists of a 10 DME arc. We followed all published instrument procedures for the arrival and approach but sometime while on the approach and IMC we passed the ATR. I feel the #1 problem is the language barrier. Not knowing what the other aircraft are saying and having to repeat everything ties up the radios. #2 problem is not knowing airspeed of other aircraft on same arrival. Another problem having 2 aircraft on the same arrival. The biggest problem and most dangerous problem in mexico for everyone is not having radar coverage below FL200.

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Original NASA ASRS Text

Title: NON RADAR APCH CTL ACR X HAD NMAC LTSS FROM ACR Y ON APCH. SYS ERROR.

Narrative: ACR X TOOK OFF FROM CUIDAD, OR, ENRTE TO HERMOSILLO, MEXICO. AN ATR HAD TAKEN OFF AHEAD OF US ALSO INBOUND TO HERMOSILLO (HMO). THE ATR WAS AT ALL TIMES AT LEAST 13 MI AHEAD OF US, ACCORDING TO POS RPTS (NON RADAR ENVIRONMENT). UPON ARR INTO HMO, WX WAS IMC, APCH CLRED X AND THE ATR FOR THE SAME ARR AND APCH INTO HERMOSILLO. X STARTED THE PUBLISHED ARR AND APCH. WE FOLLOWED OUR COMPANY PROCS AND INST PROCS, WE EXECUTED THE ARR AND APCH AND LNDG AT HERMOSILLO WITHOUT INCIDENT. WHEN X WAS CLRING THE RWY, WE NOTICED AN ATR GO OVERHEAD ON THE MISSED. WE HAD NEVER SEEN THE ATR THROUGHOUT THE ARR OR APCH. IN FACT, WE WEREN'T EVEN CERTAIN THAT THE ATR ON THE MISS WAS THE SAME ATR WE WERE FOLLOWING. WHILE WE WERE ON THE RAMP, I MONITORED TWR FREQ, I HEARD THE ATR PLT ASK THE TWR WHAT HAD HAPPENED. HE SAID HE HAD TO USE EVASIVE ACTION TO AVOID HITTING ACFT ON FINAL APCH. IN SPANISH, I HEARD THE TWR ASK THE ATR PLT TO COME UP TO THE TWR AND THAT THEY WOULD EXPLAIN WHAT HAD HAPPENED. I REALIZED IT WAS THE SAME ATR WE WERE FOLLOWING, CONFUSED AS TO WHAT HAD HAPPENED AND HOW AND WHEN WE HAD PASSED THE ATR ON THE APCH. I PROCEEDED TO GO TO THE TWR. WHEN BOTH PLTS ARRIVED AT THE TWR, APCH CTL TOLD US THAT HE SHOULDN'T HAVE CLRED US BOTH FOR THE SAME ARR, BUT THAT HE THOUGHT, BASED ON OUR POS RPTS, THAT WE HAD ADEQUATE SEPARATION. HE ALSO SAID THAT HE DIDN'T THINK X HAD EXECUTED THE ARR AS PUBLISHED, THE ATR PLT AGREED THAT X HADN'T EXECUTED THE PUBLISHED ARR. I (CAPT OF X) TOLD THEM THAT WE HAD EXECUTED THE PUBLISHED ARR AND APCH AND HADN'T DEVIATED FROM ANY CLRNC. WE DISCUSSED SEVERAL POSSIBLE FACTORS THAT COULD HAVE CAUSED THIS INCIDENT, INCLUDING DIDN'T SLOW DOWN ENOUGH ON THE ARR AND ATR SLOWED DOWN TOO MUCH. ULTIMATELY, WE ALL AGREED THAT APCH CTL SHOULD NOT CLR 2 ACFT FOR THE SAME ARR OR APCH IN A NON RADAR ENVIRONMENT. SUPPLEMENTAL INFO FROM ACN 296481: ATR TOOK OFF BEFORE US, ALSO HEADED TO HMO, MEXICO. HMO APCH TOLD US THAT THE ATR WAS 13 DME AHEAD OF US. ALL COM WITH THE ATR AND ALL OTHER ACFT WERE IN SPANISH. WE WERE CLRED FOR THE MIURA 1 ARR TO RWY 23 HMO. THE MIURA DME CONSISTS OF A 10 DME ARC. WE FOLLOWED ALL PUBLISHED INST PROCS FOR THE ARR AND APCH BUT SOMETIME WHILE ON THE APCH AND IMC WE PASSED THE ATR. I FEEL THE #1 PROB IS THE LANGUAGE BARRIER. NOT KNOWING WHAT THE OTHER ACFT ARE SAYING AND HAVING TO REPEAT EVERYTHING TIES UP THE RADIOS. #2 PROB IS NOT KNOWING AIRSPD OF OTHER ACFT ON SAME ARR. ANOTHER PROB HAVING 2 ACFT ON THE SAME ARR. THE BIGGEST PROB AND MOST DANGEROUS PROB IN MEXICO FOR EVERYONE IS NOT HAVING RADAR COVERAGE BELOW FL200.

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.