Air carrier medium large transport flight crew conducts unauthorized approach procedure at cun.

Attributes
ACN	150046
Time
Date	199007
Day	Sun
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : cun
State Reference	FO
Altitude	msl bound lower : 3000 msl bound upper : 3000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : cun
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Navigation In Use	Other Other
Flight Phase	descent : approach landing : missed approach
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 120 flight time total : 9000 flight time type : 200
ASRS Report	150046
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 7200 flight time type : 200
ASRS Report	149807
Events
Anomaly	conflict : airborne less severe non adherence : clearance non adherence : published procedure
Independent Detector	other flight crewa
Resolutory Action	other
Consequence	Other
Miss Distance	horizontal : 500 vertical : 750
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Was cleared for VOR DME 12 approach at cun. Told to maintain 3000' until 5 DME on outbnd leg. Cloud deck (ceiling), 3000'. Mindset/thought controller cleared us for visibility to maintain 3000' until 5 DME. At 5.5 DME saw airport and started turn toward airport (right turn). Was not told nor was aware of another aircraft in area. With wing up (right turn), approach path was blocked from view. We did not reconfirm clearance instructions--mexican's hard to understand. We should have flown out to 8 DME on outbnd leg, then turned as approach called for. Supplemental information from acn 149807: just as we rolled out on to the final approach course I observed an air carrier large transport Y approximately 500-1000' directly below us and faster than we were. I immediately advised the captain and he initiated a missed approach.

Original NASA ASRS Text

Title: ACR MLG FLT CREW CONDUCTS UNAUTH APCH PROC AT CUN.

Narrative: WAS CLRED FOR VOR DME 12 APCH AT CUN. TOLD TO MAINTAIN 3000' UNTIL 5 DME ON OUTBND LEG. CLOUD DECK (CEILING), 3000'. MINDSET/THOUGHT CTLR CLRED US FOR VIS TO MAINTAIN 3000' UNTIL 5 DME. AT 5.5 DME SAW ARPT AND STARTED TURN TOWARD ARPT (RIGHT TURN). WAS NOT TOLD NOR WAS AWARE OF ANOTHER ACFT IN AREA. WITH WING UP (RIGHT TURN), APCH PATH WAS BLOCKED FROM VIEW. WE DID NOT RECONFIRM CLRNC INSTRUCTIONS--MEXICAN'S HARD TO UNDERSTAND. WE SHOULD HAVE FLOWN OUT TO 8 DME ON OUTBND LEG, THEN TURNED AS APCH CALLED FOR. SUPPLEMENTAL INFO FROM ACN 149807: JUST AS WE ROLLED OUT ON TO THE FINAL APCH COURSE I OBSERVED AN ACR LGT Y APPROX 500-1000' DIRECTLY BELOW US AND FASTER THAN WE WERE. I IMMEDIATELY ADVISED THE CAPT AND HE INITIATED A MISSED APCH.

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.