B737 captain reported being cleared to land at mmun by tower. At 400 feet an unidentified voice repo...

Attributes
ACN	1338758
Time
Date	201603
Local Time Of Day	1201-1800
Place
Locale Reference	MMUN.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	IFR
Aircraft 2
Make Model Name	Skyhawk 172/Cutlass 172
Flight Phase	Taxi
Person 1
Function	Pilot Flying Captain
Qualification	Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 235 Flight Crew Total 18700 Flight Crew Type 1126
Events
Anomaly	ATC Issue All Types Conflict Ground Conflict Less Severe

Narrative:

Landing clearance issued by cancun tower by about 1200 feet AGL. Normal approach VMC with good visibility but with some haze due to opaque sky cover and humidity. At 400 feet AGL; an unidentified aircraft holding short 12R announced 'there is a cessna on the runway and you have an aircraft on short final'. At this we could now see the cessna 172 stopped on the runway obscured by its blending in with runway colors. We initiated go around and notified tower. Control tower made no reference to aircraft on runway and later asked us reason for go around. Normal go around and circle back to 12R for normal landing. Tower seemed completely unaware of conflict. We believe we would have seen the cessna prior to touchdown but at 400 feet we were in a position to land without aircraft in sight as yet due to its position 1000 feet down from runway takeoff end.

Original NASA ASRS Text

Title: B737 Captain reported being cleared to land at MMUN by Tower. At 400 feet an unidentified voice reported a C172 on the runway; which the crew could now see; and a go-around was initiated. The Tower was unaware of why the crew went around.

Narrative: Landing clearance issued by Cancun tower by about 1200 feet AGL. Normal approach VMC with good visibility but with some haze due to opaque sky cover and humidity. At 400 feet AGL; an unidentified aircraft holding short 12R announced 'there is a Cessna on the runway and you have an aircraft on short final'. At this we could now see the Cessna 172 stopped on the runway obscured by its blending in with runway colors. We initiated go around and notified tower. Control tower made no reference to aircraft on runway and later asked us reason for go around. Normal go around and circle back to 12R for normal landing. Tower seemed completely unaware of conflict. We believe we would have seen the Cessna prior to touchdown but at 400 feet we were in a position to land without aircraft in sight as yet due to its position 1000 feet down from runway takeoff end.

Data retrieved from NASA's ASRS site 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.

B737 captain reported being cleared to land at mmun by tower. At 400 feet an unidentified voice reported a C172 on the runway; which the crew could now see; and a go-around was initiated. The tower was unaware of why the crew went around.