Air carrier PIC challenges altitude change assumption with mteg acc.

Attributes
ACN	499210
Time
Date	200101
Day	Fri
Local Time Of Day	1801 To 2400
Place
State Reference	FO
Altitude	msl bound lower : 31000 msl bound upper : 32000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : mteg.artcc tower : lax.tower
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Route In Use	enroute airway : a315.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp pilot : commercial pilot : flight engineer pilot : instrument pilot : multi engine
Experience	flight time last 90 days : 80 flight time total : 6225 flight time type : 531
ASRS Report	499210
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : published procedure non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to original clearance flight crew : took precautionary avoidance action
Supplementary
Problem Areas	Flight Crew Human Performance Airspace Structure ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Incident occurred on regularly scheduled flight from aruba to nyc-jfk. At cro (cabo rojo) VOR, a fir crossing between santo domingo control (dominican republic) and port-au-price control (haiti), I made a position report at cro and FL310. Port-au-prince acknowledged the position report, and both the captain (PF) and I thought we heard 'climb to FL350, report joses (intersection/fir boundary),' which I repeated back to controller. We started a climb, and at FL320 the captain had me ask the controller to repeat the altitude clearance. We then radioed he meant us to stay at FL310, and expect FL350 later. We immediately descended back to FL310. Flight conditions were dusk (sunset) and good visibility. We saw no other traffic visually or on our TCASII presentation. Factors contributing to this incident included the controller's extremely thick accent (very hard to understand), the non radar environment of the airspace over haiti, and his phraseology for a later, to-be-assigned altitude. Neither the captain nor I heard 'expect FL350' which is our usual clue that it is not the current clearance. In the future, I will redouble my efforts to separate the current ATC clearance from a future clearance, regardless of the controller's accent or phraseology. And, of course, if there is any doubt, have them repeat it until it is understood by all parties.

Original NASA ASRS Text

Title: ACR PIC CHALLENGES ALT CHANGE ASSUMPTION WITH MTEG ACC.

Narrative: INCIDENT OCCURRED ON REGULARLY SCHEDULED FLT FROM ARUBA TO NYC-JFK. AT CRO (CABO ROJO) VOR, A FIR XING BTWN SANTO DOMINGO CTL (DOMINICAN REPUBLIC) AND PORT-AU-PRICE CTL (HAITI), I MADE A POS RPT AT CRO AND FL310. PORT-AU-PRINCE ACKNOWLEDGED THE POS RPT, AND BOTH THE CAPT (PF) AND I THOUGHT WE HEARD 'CLB TO FL350, RPT JOSES (INTXN/FIR BOUNDARY),' WHICH I REPEATED BACK TO CTLR. WE STARTED A CLB, AND AT FL320 THE CAPT HAD ME ASK THE CTLR TO REPEAT THE ALT CLRNC. WE THEN RADIOED HE MEANT US TO STAY AT FL310, AND EXPECT FL350 LATER. WE IMMEDIATELY DSNDED BACK TO FL310. FLT CONDITIONS WERE DUSK (SUNSET) AND GOOD VISIBILITY. WE SAW NO OTHER TFC VISUALLY OR ON OUR TCASII PRESENTATION. FACTORS CONTRIBUTING TO THIS INCIDENT INCLUDED THE CTLR'S EXTREMELY THICK ACCENT (VERY HARD TO UNDERSTAND), THE NON RADAR ENVIRONMENT OF THE AIRSPACE OVER HAITI, AND HIS PHRASEOLOGY FOR A LATER, TO-BE-ASSIGNED ALT. NEITHER THE CAPT NOR I HEARD 'EXPECT FL350' WHICH IS OUR USUAL CLUE THAT IT IS NOT THE CURRENT CLRNC. IN THE FUTURE, I WILL REDOUBLE MY EFFORTS TO SEPARATE THE CURRENT ATC CLRNC FROM A FUTURE CLRNC, REGARDLESS OF THE CTLR'S ACCENT OR PHRASEOLOGY. AND, OF COURSE, IF THERE IS ANY DOUBT, HAVE THEM REPEAT IT UNTIL IT IS UNDERSTOOD BY ALL PARTIES.

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.