Narrative:

Flight scheduled between gva-sal departed gva XX56 GMT. The WX was not a factor during the entire flight. Clearance was as filed. When handed over to cenamer control we were cleared to FL270 and down to FL190 at our discretion. Neither cenamer control nor el salvador approach have radar. We called cenamer control leaving FL270 for FL190 and were asked to report passing FL230. We reported passing FL230 for FL190 and were switched to san salvador approach control. We called san salvador approach control descending to FL190. We were passing about FL225 at the time of the call to approach control. Approach control asked our CAT DME and first officer replied 49 DME. Approach control twice asked our CAT DME. Our last reported DME was 46. Our rate of descent had been approximately 2500 FPM. I observed an aircraft below our altitude and at about our 12 O'clock position. The lights I saw were white wing tip lights, as neither rotating beacon nor strobes were on. Our strobes and beacon and logo lights were on. Visibility was unrestricted with no moon. We were given descent clearance to 15000' and interrupt 258 degree right to CAT VOR. We were on the arwy V6 436 on the 306 degree right off lan NDB. The first officer read back the clearance and we departed FL190 for 15000'. I watched the other aircraft which now seemed very close to our altitude. The first officer called out the traffic. I disengaged the autoplt and rolled left. The other aircraft also turned left and we passed starboard to starboard with the other aircraft below us. The other aircraft immediately started talking to san salvador approach control for about 2 mins. Approach control then told us that an air carrier plane had reported a near miss. We also reported the near miss. We asked for a reread of our clearance. Approach control never addressed a reread but instead said we were cleared to 17000' direct to VOR. We completed the descent and approach west/O further problem. I believe the air carrier aircraft was at the correct altitude. We should have been left at FL190 until passed traffic. Conversation between other aircraft and approach control was in spanish, which we could not understand. The controller at approach control should have confirmed the air carrier aircraft's DME off CAT. The air carrier aircraft should have had his beacon on. As we were above him I understand why he did not see us until we took evasive action. In a non radar area I think aircraft should keep all available lights on below FL250. The controller's english was very difficult to understand. As a result we read back clearance slowly and delayed departing FL190 until confirmed. If WX had been IFR we would not have seen the other aircraft and filed this report. At night it is very difficult to judge closure rate, especially head on. In a radar area there is a tendency to let the controller assume responsibility for traffic sep. In a VMC see and avoid sep responsibility rests with the pilot. Although I was looking I did not immediately judge the lights I saw as a threat until it was almost too late.

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Original NASA ASRS Text

Title: CTLR CLEARED MLG TO DESCEND THROUGH OCCUPIED ALT AND CAUSED A HEAD ON NMAC.

Narrative: FLT SCHEDULED BTWN GVA-SAL DEPARTED GVA XX56 GMT. THE WX WAS NOT A FACTOR DURING THE ENTIRE FLT. CLRNC WAS AS FILED. WHEN HANDED OVER TO CENAMER CTL WE WERE CLRED TO FL270 AND DOWN TO FL190 AT OUR DISCRETION. NEITHER CENAMER CTL NOR EL SALVADOR APCH HAVE RADAR. WE CALLED CENAMER CTL LEAVING FL270 FOR FL190 AND WERE ASKED TO RPT PASSING FL230. WE RPTED PASSING FL230 FOR FL190 AND WERE SWITCHED TO SAN SALVADOR APCH CTL. WE CALLED SAN SALVADOR APCH CTL DSNDING TO FL190. WE WERE PASSING ABOUT FL225 AT THE TIME OF THE CALL TO APCH CTL. APCH CTL ASKED OUR CAT DME AND F/O REPLIED 49 DME. APCH CTL TWICE ASKED OUR CAT DME. OUR LAST RPTED DME WAS 46. OUR RATE OF DSCNT HAD BEEN APPROX 2500 FPM. I OBSERVED AN ACFT BELOW OUR ALT AND AT ABOUT OUR 12 O'CLOCK POS. THE LIGHTS I SAW WERE WHITE WING TIP LIGHTS, AS NEITHER ROTATING BEACON NOR STROBES WERE ON. OUR STROBES AND BEACON AND LOGO LIGHTS WERE ON. VISIBILITY WAS UNRESTRICTED WITH NO MOON. WE WERE GIVEN DSCNT CLRNC TO 15000' AND INTERRUPT 258 DEG R TO CAT VOR. WE WERE ON THE ARWY V6 436 ON THE 306 DEG R OFF LAN NDB. THE F/O READ BACK THE CLRNC AND WE DEPARTED FL190 FOR 15000'. I WATCHED THE OTHER ACFT WHICH NOW SEEMED VERY CLOSE TO OUR ALT. THE F/O CALLED OUT THE TFC. I DISENGAGED THE AUTOPLT AND ROLLED LEFT. THE OTHER ACFT ALSO TURNED LEFT AND WE PASSED STARBOARD TO STARBOARD WITH THE OTHER ACFT BELOW US. THE OTHER ACFT IMMEDIATELY STARTED TALKING TO SAN SALVADOR APCH CTL FOR ABOUT 2 MINS. APCH CTL THEN TOLD US THAT AN ACR PLANE HAD RPTED A NEAR MISS. WE ALSO RPTED THE NEAR MISS. WE ASKED FOR A REREAD OF OUR CLRNC. APCH CTL NEVER ADDRESSED A REREAD BUT INSTEAD SAID WE WERE CLRED TO 17000' DIRECT TO VOR. WE COMPLETED THE DSCNT AND APCH W/O FURTHER PROB. I BELIEVE THE ACR ACFT WAS AT THE CORRECT ALT. WE SHOULD HAVE BEEN LEFT AT FL190 UNTIL PASSED TFC. CONVERSATION BTWN OTHER ACFT AND APCH CTL WAS IN SPANISH, WHICH WE COULD NOT UNDERSTAND. THE CTLR AT APCH CTL SHOULD HAVE CONFIRMED THE ACR ACFT'S DME OFF CAT. THE ACR ACFT SHOULD HAVE HAD HIS BEACON ON. AS WE WERE ABOVE HIM I UNDERSTAND WHY HE DID NOT SEE US UNTIL WE TOOK EVASIVE ACTION. IN A NON RADAR AREA I THINK ACFT SHOULD KEEP ALL AVAILABLE LIGHTS ON BELOW FL250. THE CTLR'S ENGLISH WAS VERY DIFFICULT TO UNDERSTAND. AS A RESULT WE READ BACK CLRNC SLOWLY AND DELAYED DEPARTING FL190 UNTIL CONFIRMED. IF WX HAD BEEN IFR WE WOULD NOT HAVE SEEN THE OTHER ACFT AND FILED THIS RPT. AT NIGHT IT IS VERY DIFFICULT TO JUDGE CLOSURE RATE, ESPECIALLY HEAD ON. IN A RADAR AREA THERE IS A TENDENCY TO LET THE CTLR ASSUME RESPONSIBILITY FOR TFC SEP. IN A VMC SEE AND AVOID SEP RESPONSIBILITY RESTS WITH THE PLT. ALTHOUGH I WAS LOOKING I DID NOT IMMEDIATELY JUDGE THE LIGHTS I SAW AS A THREAT UNTIL IT WAS ALMOST TOO LATE.

Data retrieved from NASA's ASRS site as of August 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.