Airbus Industrie Undifferentiated or Other Model
Flight Crew Air Transport Pilot (ATP)
Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Human Factors; Company Policy; Weather
Enroute to ZGGG there was a line of very active thunderstorms between ZZZZ and ZGGG (east to west moving at about 50 KTS at altitude). To get into ZGGG airspace we had to deviate 100 NM east of ZZZZ and snake our way around many storms. We expected an approach to Runway 20L. As we neared the ZGGG airport; ATC informed us that Runway 02R was now in use and then we had to work our way around more storms to make progress on radar downwind for the approach on about heading 200 degrees. As we passed abeam the approach end of Runway 02R; I informed ATC that we would need a shorter turn to final approach due to a big storm on final at about 12 NM. They acknowledged their understanding. We were cleared descent to 1;800 meters and to slow to 180 KTS; slats came out followed by flaps 15 and the descent rate was reduced to make the deceleration. We were in a slow and easy descent and expected a turn to base leg in about 5-6 miles. Then ATC made a frantic; very excited transmission for an aircraft to descend to or maintain 1;800 meters and turn right to a heading of about 300 degrees (the transmission wasn't very clear and the voice was very frantic and abrupt so the exact heading may be different). I did not hear a call sign with the transmission. ATC repeated the frantic message now instructing the aircraft to climb to 2;100 meters and make the right turn and I thought I heard part of a call sign. I keyed the mike and asked for the call sign to be repeated; 'Repeat call sign; call sign.' ATC said it was for us! At the same time the TCAS sounded with a 'Traffic; Traffic' alert and I looked down to see a yellow triangle symbol ahead and about 45 degrees to the left at 600 FT below our altitude. I don't know the distance as the Airbus TCAS is not so easy to read (I had confidence and experience using a TCAS display on the ND); especially in the adverse conditions (it was dark and stormy; we were reacting to a frantic call from ATC to some aircraft that turned out to be us; changing instructions with a requirement to convert all altitude instructions from meters to feet using a decoder card and English as a second language for the controllers). It may have been 3-4 miles. We still had 12 NM range selected and I didn't notice any aircraft displayed until then. I announced what I saw on the TCAS at about the same time as the Captain disconnected the autopilot and followed ATC's instructions. There was no RA alert. I believe that ATC then instructed [the other aircraft] to maintain 1;800 meters and make a conflict deviation turn; followed by a descent to 900 meters and then make progress to final approach. It appeared that aircraft was on radar base leg flying left to right ahead of us while we were on downwind. Once we followed ATC's instructions the conflict was over; things settled down very quickly and we continued and flew the ILS to Runway 02R.  I thought ATC had done a fairly good job letting all the arrival aircraft make their own storm deviations with so many storms in the area but at the time of the conflict I think ATC confused the two aircraft on their displays when one was on downwind and the other on base leg and in very close proximity with a storm limiting the maneuvering airspace for the approach. I think he gave us a descent to 1;800 meters when he intended it for the other airplane. Then we descended into their flight path. I don't recall any other call sign confusion until that point and never felt confused myself by the different call signs in the pattern. Company use of call signs that are so similar to each other in the same location and same time are very confusing for both the controllers and the pilots. Do not use very similar call signs in the same location and time.
After much weather deviation we were positioning for approach to Runway 20L. ATC (from HK Radar through Zuhai and Guangzhou Approach) was doing a good job of working with the crews to allow us to plot our course to remain clear of the adverse weather. After a runway change was made to [Runway] 02R we were instructed to turn south and descend from 2;100 meters to 1;800 meters and slow to 180 KTS. We acknowledged their radio call to us and began the turn; began slowing to 180 KTS and called for flaps 15 to begin the descent. Descent rate was shallow due to the slowing of the aircraft to 180 KTS. Shortly thereafter ATC broadcast an emphatic radio call for 'Company ABC? to maintain 1;800 meters' and 'IMMEDIATELY; IMMEDIATELY Company ABC? maintain 2;100 meters'; and then 'I say again Company ABCD climb maintain 2;100 meters. Make right turn 300 immediately.' (Not real clear of the heading due to the 'emphatic tone' of his voice but that course put us toward a large thunderstorm in our path. He also instructed the other aircraft to 'Maintain 1;800 meters and make an avoidance turn (heading also escapes me at this point.) We also got a 'Traffic; Traffic' call. At that point; we disconnected the autopilot and autothrottles and reversed the descent and began the climb to 2;100 meters. We did not get an RA and followed ATC's instruction; remaining clear of the other aircraft. After clear I asked the First Officer to 'reautomate me so we could concentrate on the positions of the aircraft.' The First Officer did an excellent job of communicating with ATC again asking them to clarify 'call sign; call sign...' We remained level at 2;100 meters and the event was over. After that ATC instructed the other aircraft to descend to 900 meters and being on base they were then cleared approach to [Runway] 02R. We turned to base shortly thereafter and descended to 900 meters and also flew a normal ILS to [Runway] 02R. We thought ATC did a good job of working with us and the other aircraft that made it into CAN that night helping us avoid the worst of the weather. This may have been a simple call sign transposition that caused two aircraft close to each other; (with very similar call signs) to experience a descent closure resulting in a 'Traffic; Traffic' call. ATC recognized the pending situation and took aggressive steps to notify the aircraft of required actions to mitigate the threat.DO NOT USE COMPANY CALL SIGNS [with one digit difference] (or similar call signs like that) AT THE SAME TIME AND LOCATION. (This has caused problems before not only for us; but also ATC and other aircraft on frequency.) Please come up with a better system.
Air Carrier flight crew describes an airborne conflict that develops when a Controller confuses similar call signs (one digit difference) descending a second aircraft to an occupied altitude. The error is detected and corrected by the Controller in a timely manor.