Narrative:

We were cruising at 8000', expecting a turn off the arwy at irons intersection for vectors at dca. They were using the lda 18, so it was normal to stay higher longer. While my first officer was off frequency, I heard a descent for an aircraft to 6000', but I was unable to verify it (the controller was very busy). After a few moments (my first officer was on frequency now), we were given a descent to 4000', which was read back as '...8 for 4000'.' as we passed 5000', the controller asked what altitude we were descending to, and my first officer replied 'out of 5000 for 4.' at this point I slowed our descent and asked for verification, to which we received no reply. After several additional attempts,the controller finally said, 'I thought I only cleared you to 6000, but I have changed it. Continue your descent to 4000,' and nothing more was mentioned. We continued the approach and nothing more was said about the discrepancy. After landing we discussed the problem and concluded the following: 1) we heard our call sign being cleared to 4000' and was readback as such. 2) the controller refused to answer to our verifications and was extremely overloaded during the time in question. 3) the controller also changed his clearance to 4000' and said nothing again of any discrepancy in the altitudes. I always receive literature on pilot/controller programs, but the readback/listenback system is as weak as its users. If this controller had a problem with our altitude clearance, then he should have heard our readback--and surely if he was as overworked as he sounded, then maybe he should have gotten some help.

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Original NASA ASRS Text

Title: MDT FLT CREW GIVEN DESCENT CLRNC. LATER CTLR ASKED WHAT ALT, AND THEN 'I THOUGHT I CLEARED YOU TO 6000'.'

Narrative: WE WERE CRUISING AT 8000', EXPECTING A TURN OFF THE ARWY AT IRONS INTXN FOR VECTORS AT DCA. THEY WERE USING THE LDA 18, SO IT WAS NORMAL TO STAY HIGHER LONGER. WHILE MY F/O WAS OFF FREQ, I HEARD A DSCNT FOR AN ACFT TO 6000', BUT I WAS UNABLE TO VERIFY IT (THE CTLR WAS VERY BUSY). AFTER A FEW MOMENTS (MY F/O WAS ON FREQ NOW), WE WERE GIVEN A DSCNT TO 4000', WHICH WAS READ BACK AS '...8 FOR 4000'.' AS WE PASSED 5000', THE CTLR ASKED WHAT ALT WE WERE DSNDING TO, AND MY F/O REPLIED 'OUT OF 5000 FOR 4.' AT THIS POINT I SLOWED OUR DSCNT AND ASKED FOR VERIFICATION, TO WHICH WE RECEIVED NO REPLY. AFTER SEVERAL ADDITIONAL ATTEMPTS,THE CTLR FINALLY SAID, 'I THOUGHT I ONLY CLRED YOU TO 6000, BUT I HAVE CHANGED IT. CONTINUE YOUR DSCNT TO 4000,' AND NOTHING MORE WAS MENTIONED. WE CONTINUED THE APCH AND NOTHING MORE WAS SAID ABOUT THE DISCREPANCY. AFTER LNDG WE DISCUSSED THE PROB AND CONCLUDED THE FOLLOWING: 1) WE HEARD OUR CALL SIGN BEING CLRED TO 4000' AND WAS READBACK AS SUCH. 2) THE CTLR REFUSED TO ANSWER TO OUR VERIFICATIONS AND WAS EXTREMELY OVERLOADED DURING THE TIME IN QUESTION. 3) THE CTLR ALSO CHANGED HIS CLRNC TO 4000' AND SAID NOTHING AGAIN OF ANY DISCREPANCY IN THE ALTS. I ALWAYS RECEIVE LITERATURE ON PLT/CTLR PROGRAMS, BUT THE READBACK/LISTENBACK SYS IS AS WEAK AS ITS USERS. IF THIS CTLR HAD A PROB WITH OUR ALT CLRNC, THEN HE SHOULD HAVE HEARD OUR READBACK--AND SURELY IF HE WAS AS OVERWORKED AS HE SOUNDED, THEN MAYBE HE SHOULD HAVE GOTTEN SOME HELP.

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.