Narrative:

Dfw was in a north flow configuration departing runways 36R and 35L. The weather was VFR with clear skies. I was working departure 2 and 3 combined; which works departures out our 4 north routes; 4 west routes and 2 of our 4 south routes. Traffic load was steady and nothing out of the ordinary. An air carrier X departed off runway 36R on a heading of 340; climbing to 10;000 ft; which signified to me that they were unable to fly an RNAV departure and I would vector them to join their routing. Their initial call was incoherent and I recognized the call sign as being one that doesn't speak english as well as other pilots. Approximately 5 miles north I turned them left to a heading of 270 which was read back without incident. A few miles later I issued traffic to the air carrier X at one o'clock; 8 miles; southeast bound; an MD80 at 11;000. They responded that they were looking. I then instructed the air carrier X to 'turn left heading 220.' the air carrier X read back; '220; [call sign air carrier X].' no other words were used in the air carrier X's read back. A few seconds later; two aircraft departing dfw on RNAV departures called me at the same time on different frequencies. One had departed on an RNAV departure off 35L for a north route while the other had departed 36R on an RNAV for a west route. I informed the aircraft that there were two calling at once on different frequencies; and then proceeded to radar identify each aircraft and climbed the north route to 17;000. I then turned my attention to the air carrier X who was in a climb and still headed westbound. I asked the air carrier X to say his altitude and instructed him to turn left heading 220 immediately. He had already crossed through the flight path of the traffic I issued and was climbing into a second arrival aircraft at 11;000. The air carrier X responded 'we are leaving 11;300 for 2-2-0 and we responded to a TCAS advisory.' I told the air carrier X to turn and maintain 17;000. I got a correct read back and questioned why they had climbed into the traffic I had just issued. They responded that there was some confusion and that they had read back 'climb to 2-2-0.' I continued working other traffic and was able to get the air carrier X on their way. I later asked them if there was confusion; then why would they climb into traffic I had just issued and not verify the instruction. They told me there was a lot going on in the cockpit and that I should just file a report. I responded that I would and called a supervisor over to my sector to report the incident. Since I only saw the air carrier X's altitude after he had passed the MD80; I informed the supervisor I was unaware of any loss of separation and that the air carrier X reported responding to a TCAS advisory. After further review of the incident; management informed me that there was no loss of separation. I asked about the audio to see if I in fact had missed the read back as the air carrier X had suggested. I was informed that I clearly stated the instruction of 'turn left heading 2-2-0;' and the air carrier X's read back consisted of only '2-2-0 [call sign air carrier X].' I listened to the audio to confirm for myself that the numbers and call sign were the only things received on frequency. They were. To my knowledge the MD80 did not respond to a TCAS advisory; and the controller working the MD80 did not need to take action to avoid traffic. An incident like this happens far too often with foreign pilots; but normally we are able to catch it and fix it without incident. In my opinion; foreign pilots are far too careless when it comes to reading back instructions. Normally they respond with what they want to do as opposed to what they were instructed to do. In this case; the read back was sufficient to believe they would follow instructions. Had they said 'flight level 2-2-0'; then that should have caught my attention that they were going to climb. However since all they read back was '2-2-0;' I expected a turn as any controller would. They also stated to me that there was confusion on their part. If that's the case then they need to verify their instructions as opposed to doing what they think is right. Most english speaking pilots do this. For any pilot; I believe it should be expected to question an instruction if there is confusion or a misunderstanding. No different from us as controllers verifying a pilot's read back if there is confusion on our part. I realize that incidents like this will happen due to the language barrier; but they can be prevented by holding these pilots accountable for not questioning an instruction if they were confused. It also concerns me that this pilot in particular cleaned up his english; was sharper with responses; and told me just to file a report after the incident.

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Original NASA ASRS Text

Title: D10 Controller described a TCAS RA event listing language barrier as the primary causal factor.

Narrative: DFW was in a north flow configuration departing Runways 36R and 35L. The weather was VFR with clear skies. I was working Departure 2 and 3 combined; which works departures out our 4 north routes; 4 west routes and 2 of our 4 south routes. Traffic load was steady and nothing out of the ordinary. An Air Carrier X departed off Runway 36R on a heading of 340; climbing to 10;000 FT; which signified to me that they were unable to fly an RNAV departure and I would vector them to join their routing. Their initial call was incoherent and I recognized the call sign as being one that doesn't speak English as well as other pilots. Approximately 5 miles north I turned them left to a heading of 270 which was read back without incident. A few miles later I issued traffic to the Air Carrier X at one o'clock; 8 miles; southeast bound; an MD80 at 11;000. They responded that they were looking. I then instructed the Air Carrier X to 'Turn left heading 220.' The Air Carrier X read back; '220; [call sign Air Carrier X].' No other words were used in the Air Carrier X's read back. A few seconds later; two aircraft departing DFW on RNAV departures called me at the same time on different frequencies. One had departed on an RNAV departure off 35L for a north route while the other had departed 36R on an RNAV for a west route. I informed the aircraft that there were two calling at once on different frequencies; and then proceeded to RADAR identify each aircraft and climbed the north route to 17;000. I then turned my attention to the Air Carrier X who was in a climb and still headed westbound. I asked the Air Carrier X to say his altitude and instructed him to turn left heading 220 immediately. He had already crossed through the flight path of the traffic I issued and was climbing into a second arrival aircraft at 11;000. The Air Carrier X responded 'we are leaving 11;300 for 2-2-0 and we responded to a TCAS advisory.' I told the Air Carrier X to turn and maintain 17;000. I got a correct read back and questioned why they had climbed into the traffic I had just issued. They responded that there was some confusion and that they had read back 'climb to 2-2-0.' I continued working other traffic and was able to get the Air Carrier X on their way. I later asked them if there was confusion; then why would they climb into traffic I had just issued and not verify the instruction. They told me there was a lot going on in the cockpit and that I should just file a report. I responded that I would and called a Supervisor over to my sector to report the incident. Since I only saw the Air Carrier X's altitude after he had passed the MD80; I informed the Supervisor I was unaware of any loss of separation and that the Air Carrier X reported responding to a TCAS advisory. After further review of the incident; Management informed me that there was no loss of separation. I asked about the audio to see if I in fact had missed the read back as the Air Carrier X had suggested. I was informed that I clearly stated the instruction of 'Turn left heading 2-2-0;' and the Air Carrier X's read back consisted of only '2-2-0 [call sign Air Carrier X].' I listened to the audio to confirm for myself that the numbers and call sign were the only things received on frequency. They were. To my knowledge the MD80 did not respond to a TCAS advisory; and the Controller working the MD80 did not need to take action to avoid traffic. An incident like this happens far too often with foreign pilots; but normally we are able to catch it and fix it without incident. In my opinion; foreign pilots are far too careless when it comes to reading back instructions. Normally they respond with what they want to do as opposed to what they were instructed to do. In this case; the read back was sufficient to believe they would follow instructions. Had they said 'Flight Level 2-2-0'; then that should have caught my attention that they were going to climb. However since all they read back was '2-2-0;' I expected a turn as any controller would. They also stated to me that there was confusion on their part. If that's the case then they need to verify their instructions as opposed to doing what they think is right. Most English speaking pilots do this. For any pilot; I believe it should be expected to question an instruction if there is confusion or a misunderstanding. No different from us as controllers verifying a pilot's read back if there is confusion on our part. I realize that incidents like this will happen due to the language barrier; but they can be prevented by holding these pilots accountable for not questioning an instruction if they were confused. It also concerns me that this pilot in particular cleaned up his English; was sharper with responses; and told me just to file a report after the incident.

Data retrieved from NASA's ASRS site as of July 2013 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.