Narrative:

Aircraft X departed dal on a vector southeast bound climbing to 5;000. I radar identified the aircraft and climbed him to 8;000. Approximately 5 miles later; I turned him to a 180 heading and climbed aircraft X to 10;000 for numerous arrival aircraft into dfw on the STAR at 11;000. Once I had separation with other aircraft on departures; I instructed aircraft X to 'proceed direct to nelyn and resume the departure.' his read back was extremely garbled and he did not speak english very well. I restated to 'proceed direct nelyn and resume the departure.' I then turned my attention to other aircraft. When I scanned back to aircraft X he was climbing out of 10;800 and still on a 180 heading. His departure routing would take him southwest on about a 230 heading. I instructed him to 'descend immediately to 10;000.' this instruction had to be given twice before a proper response was read back. Aircraft Y had already passed behind him but the wake turbulence separation had been lost. Several attempts to turn aircraft X were also made; with no response from the pilot. Coordination then had to be accomplished quickly with waco approach and fort worth center in order to transfer radar with the next sector. Aircraft X clearly did not speak english very well. I spoke slowly using appropriate phraseology hoping to avoid the situation previously described. Other than renaming the fix on the departure route; I don't believe this situation can be avoided unless the FAA becomes more strict on pilots to learn/understand english. The fix nelyn; which is commonly used for aircraft X's departure routing; must have sounded like eleven. However; since I used the phraseology of 'proceed direct to (name of fix) and resume the departure;' I don't know how the pilot could mistake it for altitude since climb; maintain; and thousand were never spoken in his clearance. Even after this incident it took several transmissions for the pilot to acknowledge any type of clearance. This was the second time today that foreign aircraft did not speak english well and did not follow instructions. This time however; a separation loss occurred because of it.

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Original NASA ASRS Text

Title: D10 Controller experienced a loss of separation event when a DAL departure failed to follow route instructions; the reporter claiming lack of pilot language skills caused the event.

Narrative: Aircraft X departed DAL on a vector southeast bound climbing to 5;000. I RADAR identified the aircraft and climbed him to 8;000. Approximately 5 miles later; I turned him to a 180 heading and climbed Aircraft X to 10;000 for numerous arrival aircraft into DFW on the STAR at 11;000. Once I had separation with other aircraft on departures; I instructed Aircraft X to 'proceed direct to NELYN and resume the departure.' His read back was extremely garbled and he did not speak English very well. I restated to 'proceed direct NELYN and resume the departure.' I then turned my attention to other aircraft. When I scanned back to Aircraft X he was climbing out of 10;800 and still on a 180 heading. His departure routing would take him southwest on about a 230 heading. I instructed him to 'descend immediately to 10;000.' This instruction had to be given twice before a proper response was read back. Aircraft Y had already passed behind him but the wake turbulence separation had been lost. Several attempts to turn Aircraft X were also made; with no response from the pilot. Coordination then had to be accomplished quickly with Waco Approach and Fort Worth Center in order to transfer RADAR with the next sector. Aircraft X clearly did not speak English very well. I spoke slowly using appropriate phraseology hoping to avoid the situation previously described. Other than renaming the fix on the departure route; I don't believe this situation can be avoided unless the FAA becomes more strict on pilots to learn/understand English. The fix NELYN; which is commonly used for Aircraft X's departure routing; must have sounded like eleven. However; since I used the phraseology of 'proceed direct to (name of fix) and resume the departure;' I don't know how the pilot could mistake it for altitude since climb; maintain; and thousand were never spoken in his clearance. Even after this incident it took several transmissions for the pilot to acknowledge any type of clearance. This was the second time today that foreign aircraft did not speak English well and did not follow instructions. This time however; a separation loss occurred because of it.

Data retrieved from NASA's ASRS site as of April 2012 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.