A descending DC8 freighter is cleared in error to FL120 versus FL210, north of heca, first officer.

Attributes
ACN	437838
Time
Date	199905
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : heca.airport
State Reference	FO
Altitude	msl bound lower : 180 msl bound upper : 210
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : hecc.artcc
Operator	common carrier : air carrier
Make Model Name	DC-8 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 140 flight time total : 4500 flight time type : 1800
ASRS Report	437838
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 9100 flight time type : 7500
ASRS Report	437971
Events
Anomaly	conflict : airborne less severe
Independent Detector	other controllera
Resolutory Action	controller : separated traffic controller : issued alert
Supplementary
Problem Areas	Airspace Structure Environmental Factor ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Deviation
Situations
ATC Facility	communication equipment : hecc.artcc

Narrative:

Cairo center had cleared us to descend FL210. During the descent at approximately FL235 center said 'descend and maintain FL120. I set the altitude in the alerter, the captain and engineer both responded. At approximately FL180 cairo center told us to 'climb, climb FL210' then stop climb FL200 then again climb FL210. We did all this. I feel that due to difficulty communicating in english that this controller reversed the numbers in his clearance, intending to say FL210 he said FL120 and didn't catch my readback. Supplemental information from acn 437971: cairo radios are poor and accents added to situation.

Original NASA ASRS Text

Title: A DSNDING DC8 FREIGHTER IS CLRED IN ERROR TO FL120 VERSUS FL210, N OF HECA, FO.

Narrative: CAIRO CENTER HAD CLRED US TO DSND FL210. DURING THE DSCNT AT APPROX FL235 CTR SAID 'DSND AND MAINTAIN FL120. I SET THE ALT IN THE ALERTER, THE CAPT AND ENGINEER BOTH RESPONDED. AT APPROX FL180 CAIRO CTR TOLD US TO 'CLB, CLB FL210' THEN STOP CLB FL200 THEN AGAIN CLB FL210. WE DID ALL THIS. I FEEL THAT DUE TO DIFFICULTY COMMUNICATING IN ENGLISH THAT THIS CTLR REVERSED THE NUMBERS IN HIS CLRNC, INTENDING TO SAY FL210 HE SAID FL120 AND DIDN'T CATCH MY READBACK. SUPPLEMENTAL INFO FROM ACN 437971: CAIRO RADIOS ARE POOR AND ACCENTS ADDED TO SIT.

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.