Narrative:

While climbing out on capitol 2 departure from iad we were cleared to climb to 17000' by bwi departure (in VMC conditions [night] and smooth air). A min or so later the captain, who was flying on autoplt, and I both heard the controller say, 'maintain 14000'.' while the captain selected 14000' on the altitude selector I acknowledged, 'roger, maintain 14000',' and my call sign. There was no response from the controller. A few more mins elapsed after we leveled at 14000'. I then overheard the conversation between the controller and another air carrier. In that conversation the controller pointed out traffic to the air carrier that was maintaining a good rate through 14000' to maintain 17000'. Something made me wonder if we were the traffic in reference. I then asked the captain if he also felt that maybe we were still cleared to 17000'. He was not sure so I asked to controller but my first transmission was blocked. So again, I asked, 'do you want (my call sign) to maintain 14000?' at that same time I saw the conflicting traffic at my 1:30 position moving right to left and appeared close to our altitude about 1/2-3/4 mi away. Also, at the same time, the controller, realizing the conflict ordered us to make an immediate right turn and climb, which we were already in the process of doing having spotted the traffic. The turn was sharp but not abrupt as to alarm any of our passenger. The controller then cleared us to 17000' and not another word was said. This points out a critical weak link in the system--many controllers do not listen to pilots when they read back a clearance. If he had, this conflict would not have occurred. The words, 'maintain' and 'good rate,' can sound very similar when said quickly over the radio.

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Original NASA ASRS Text

Title: MLG TOOK EVASIVE ACTION TO AVOID CONFLICT WITH CONVERGING ACR.

Narrative: WHILE CLBING OUT ON CAPITOL 2 DEP FROM IAD WE WERE CLRED TO CLB TO 17000' BY BWI DEP (IN VMC CONDITIONS [NIGHT] AND SMOOTH AIR). A MIN OR SO LATER THE CAPT, WHO WAS FLYING ON AUTOPLT, AND I BOTH HEARD THE CTLR SAY, 'MAINTAIN 14000'.' WHILE THE CAPT SELECTED 14000' ON THE ALT SELECTOR I ACKNOWLEDGED, 'ROGER, MAINTAIN 14000',' AND MY CALL SIGN. THERE WAS NO RESPONSE FROM THE CTLR. A FEW MORE MINS ELAPSED AFTER WE LEVELED AT 14000'. I THEN OVERHEARD THE CONVERSATION BTWN THE CTLR AND ANOTHER ACR. IN THAT CONVERSATION THE CTLR POINTED OUT TFC TO THE ACR THAT WAS MAINTAINING A GOOD RATE THROUGH 14000' TO MAINTAIN 17000'. SOMETHING MADE ME WONDER IF WE WERE THE TFC IN REF. I THEN ASKED THE CAPT IF HE ALSO FELT THAT MAYBE WE WERE STILL CLRED TO 17000'. HE WAS NOT SURE SO I ASKED TO CTLR BUT MY FIRST XMISSION WAS BLOCKED. SO AGAIN, I ASKED, 'DO YOU WANT (MY CALL SIGN) TO MAINTAIN 14000?' AT THAT SAME TIME I SAW THE CONFLICTING TFC AT MY 1:30 POS MOVING RIGHT TO LEFT AND APPEARED CLOSE TO OUR ALT ABOUT 1/2-3/4 MI AWAY. ALSO, AT THE SAME TIME, THE CTLR, REALIZING THE CONFLICT ORDERED US TO MAKE AN IMMEDIATE RIGHT TURN AND CLB, WHICH WE WERE ALREADY IN THE PROCESS OF DOING HAVING SPOTTED THE TFC. THE TURN WAS SHARP BUT NOT ABRUPT AS TO ALARM ANY OF OUR PAX. THE CTLR THEN CLRED US TO 17000' AND NOT ANOTHER WORD WAS SAID. THIS POINTS OUT A CRITICAL WEAK LINK IN THE SYS--MANY CTLRS DO NOT LISTEN TO PLTS WHEN THEY READ BACK A CLRNC. IF HE HAD, THIS CONFLICT WOULD NOT HAVE OCCURRED. THE WORDS, 'MAINTAIN' AND 'GOOD RATE,' CAN SOUND VERY SIMILAR WHEN SAID QUICKLY OVER THE RADIO.

Data retrieved from NASA's ASRS site as of August 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.