Narrative:

Flight was approximately 100 NM southwest of mmcu in mexico when we experienced a rapid loss of cabin pressure. Flight descended from FL350 and recovered pressure at approximately FL180. Crew climbed back to FL310 and once again experienced pressure loss at this point. The captain decided to divert to elp and advised that he tried to contact dispatch, but was unable. The aircraft did not have HF radio, so no voice patch was available. ACARS was not in range as messages did not transmit. The captain said he asked monterey ATC to contact dispatch and gave them my desk number. Mmty center did not call dispatch. They called mazatlan center to cancel flight abc's flight plan. Mmzt center called sjd operations who then called dispatch. By then, the story was that flight abc had an emergency depressurization and mmty had lost communication with them after passing them to ZAB. I started a search for flight abc. ACARS messages were not answered. Mmty center said that they no longer had contact with them. Abz center said they did not have them as yet. They said they showed him on the tsd heading south through mexico. At that point, elp operations called and said he was on the inbound with no emergency. I then spoke to elp tower who confirmed his inbound. He was not declaring an emergency. He relayed pressure loss and getting low on fuel. The flight landed without incident. The captain explained both pressure losses as a mystery, but also expressed that he was unable to contact dispatch. This definitely qualifies as a loss of company communications. Based on the information provided to me by ATC, I had a flight in mexico airspace in terrain who had experienced an emergency depressurization whom I was unable to contact and whom both controling sectors said they did not have contact with. I was about to declare a missing aircraft when elp operations called. The time span from initial notification by sjd operations to dispatch from the time confirmed aircraft approach to elp was about 20 mins. This is the time frame I consider the flight missing. Actual loss of company communications time frame could be considerably longer.

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Original NASA ASRS Text

Title: RPT BY DISPATCHER STATES THAT UNKNOWN ACR TYPE ACFT SUFFERED LOSS OF PRESSURIZATION OVER HAZARDOUS TERRAIN IN NORTHERN MEXICO. DURING EMER DSCNT, ACFT LOST CONTACT WITH ARTCC AND WITH DISPATCH. JUST PRIOR TO INITIATING A SEARCH FOR THE ACFT, THE RPTR WAS NOTIFIED IT WAS ON FINAL TO A DOMESTIC ARPT TO WHICH IT HAD DEVIATED.

Narrative: FLT WAS APPROX 100 NM SW OF MMCU IN MEXICO WHEN WE EXPERIENCED A RAPID LOSS OF CABIN PRESSURE. FLT DSNDED FROM FL350 AND RECOVERED PRESSURE AT APPROX FL180. CREW CLBED BACK TO FL310 AND ONCE AGAIN EXPERIENCED PRESSURE LOSS AT THIS POINT. THE CAPT DECIDED TO DIVERT TO ELP AND ADVISED THAT HE TRIED TO CONTACT DISPATCH, BUT WAS UNABLE. THE ACFT DID NOT HAVE HF RADIO, SO NO VOICE PATCH WAS AVAILABLE. ACARS WAS NOT IN RANGE AS MESSAGES DID NOT XMIT. THE CAPT SAID HE ASKED MONTEREY ATC TO CONTACT DISPATCH AND GAVE THEM MY DESK NUMBER. MMTY CTR DID NOT CALL DISPATCH. THEY CALLED MAZATLAN CTR TO CANCEL FLT ABC'S FLT PLAN. MMZT CTR CALLED SJD OPS WHO THEN CALLED DISPATCH. BY THEN, THE STORY WAS THAT FLT ABC HAD AN EMER DEPRESSURIZATION AND MMTY HAD LOST COM WITH THEM AFTER PASSING THEM TO ZAB. I STARTED A SEARCH FOR FLT ABC. ACARS MESSAGES WERE NOT ANSWERED. MMTY CTR SAID THAT THEY NO LONGER HAD CONTACT WITH THEM. ABZ CTR SAID THEY DID NOT HAVE THEM AS YET. THEY SAID THEY SHOWED HIM ON THE TSD HDG S THROUGH MEXICO. AT THAT POINT, ELP OPS CALLED AND SAID HE WAS ON THE INBOUND WITH NO EMER. I THEN SPOKE TO ELP TWR WHO CONFIRMED HIS INBOUND. HE WAS NOT DECLARING AN EMER. HE RELAYED PRESSURE LOSS AND GETTING LOW ON FUEL. THE FLT LANDED WITHOUT INCIDENT. THE CAPT EXPLAINED BOTH PRESSURE LOSSES AS A MYSTERY, BUT ALSO EXPRESSED THAT HE WAS UNABLE TO CONTACT DISPATCH. THIS DEFINITELY QUALIFIES AS A LOSS OF COMPANY COMS. BASED ON THE INFO PROVIDED TO ME BY ATC, I HAD A FLT IN MEXICO AIRSPACE IN TERRAIN WHO HAD EXPERIENCED AN EMER DEPRESSURIZATION WHOM I WAS UNABLE TO CONTACT AND WHOM BOTH CTLING SECTORS SAID THEY DID NOT HAVE CONTACT WITH. I WAS ABOUT TO DECLARE A MISSING ACFT WHEN ELP OPS CALLED. THE TIME SPAN FROM INITIAL NOTIFICATION BY SJD OPS TO DISPATCH FROM THE TIME CONFIRMED ACFT APCH TO ELP WAS ABOUT 20 MINS. THIS IS THE TIME FRAME I CONSIDER THE FLT MISSING. ACTUAL LOSS OF COMPANY COMS TIME FRAME COULD BE CONSIDERABLY LONGER.

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.