Altitude deviation altitude excursion from assigned in foreign airspace.

Attributes
ACN	343420
Time
Date	199608
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : mmzt
State Reference	FO
Altitude	msl bound lower : 28000 msl bound upper : 31000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : mmzt
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	descent other
Route In Use	arrival : profile descent arrival other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
ASRS Report	343420
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	343423
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : became reoriented
Consequence	Other
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	Pilot Deviation

Narrative:

ATC facility: mazatlan. Location: caliz. As I returned to my first officer seat after going to the latrine, the airplane was in a descent. The captain said we had been cleared to FL210, but that it seemed to him too early to descend. The captain then confirmed the descent to FL210 with the mazatlan controller who said we were to maintain FL310. We stopped our descent at FL280 and climbed back to FL310 and the WX was VFR. The distorted reply by mazatlan -- their xmissions sound like they are coming from inside a barrel -- when the captain initially checked in, sounded like a clearance to descend to FL210 instead of to maintain FL310. Supplemental information from acn 343423: we had been rerouted. Over caliz we switched to mmzt. Their xmissions were very scratchy and distorted.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION FROM ASSIGNED IN FOREIGN AIRSPACE.

Narrative: ATC FACILITY: MAZATLAN. LOCATION: CALIZ. AS I RETURNED TO MY FO SEAT AFTER GOING TO THE LATRINE, THE AIRPLANE WAS IN A DSCNT. THE CAPT SAID WE HAD BEEN CLRED TO FL210, BUT THAT IT SEEMED TO HIM TOO EARLY TO DSND. THE CAPT THEN CONFIRMED THE DSCNT TO FL210 WITH THE MAZATLAN CTLR WHO SAID WE WERE TO MAINTAIN FL310. WE STOPPED OUR DSCNT AT FL280 AND CLBED BACK TO FL310 AND THE WX WAS VFR. THE DISTORTED REPLY BY MAZATLAN -- THEIR XMISSIONS SOUND LIKE THEY ARE COMING FROM INSIDE A BARREL -- WHEN THE CAPT INITIALLY CHKED IN, SOUNDED LIKE A CLRNC TO DSND TO FL210 INSTEAD OF TO MAINTAIN FL310. SUPPLEMENTAL INFO FROM ACN 343423: WE HAD BEEN REROUTED. OVER CALIZ WE SWITCHED TO MMZT. THEIR XMISSIONS WERE VERY SCRATCHY AND DISTORTED.

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.