Narrative:

After sweet intersection given a 040 degree heading; cleared to 6000 ft. At above position ATC cleared us to 3000 ft. I set 3000 ft in the altitude controller; read back 'air carrier X cleared to 3000 ft' and remarked to the first officer this was unusual as we were still outside the class B airspace. Approaching 5000 ft we saw a gulfstream to our 10 O'clock position about 4 mi converging sebound. I remarked 'traffic at 10 O'clock low; left to right; he's probably on the VOR-a into teterboro.' it became apparent there was going to be a conflict and as I was about to direct the first officer to level off ATC said 'air carrier X climb back to 5000 immediately' (we were at 4400 ft at the time). I responded 'climbing back to 5000 ft; you gave us 3000 ft.' he retorted 'I gave you 5 thousand.' we climbed back to 5000 ft; the gulfstream passed about a half mi or so in front of us and below. Both myself and the first officer confirmed we had been given 3000 ft as a clearance. There was no doubt in our minds. There was no TCAS RA and no evasive vectors issued. There were no distrs in the cockpit; and we were well rested. ATC; however; seemed very busy indeed. On the human factors note; there is an endemic problem arising in the ATC system. It is my impression that of late the nyc and ord approachs are trying to cram even more airplanes into the already overcrowded airspace; and safety is starting to be compromised as mistakes are made; separation standards reduced; and readbacks unheard. Rather than look at what we can do to make the parties perform better (they are already performing beyond expectations) we should look at the structure of the problem; and start reducing the number of airplanes in the system at the busier airports. We simply do not have the real estate available; and no amount of technology will usurp the physical laws constraining airplanes flying closely together in the atmosphere.

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Original NASA ASRS Text

Title: A320 FLT CREW HAS ALTDEV DURING APCH AND HAS AN AIRBORNE CONFLICT.

Narrative: AFTER SWEET INTXN GIVEN A 040 DEG HDG; CLRED TO 6000 FT. AT ABOVE POS ATC CLRED US TO 3000 FT. I SET 3000 FT IN THE ALT CTLR; READ BACK 'ACR X CLRED TO 3000 FT' AND REMARKED TO THE FO THIS WAS UNUSUAL AS WE WERE STILL OUTSIDE THE CLASS B AIRSPACE. APCHING 5000 FT WE SAW A GULFSTREAM TO OUR 10 O'CLOCK POS ABOUT 4 MI CONVERGING SEBOUND. I REMARKED 'TFC AT 10 O'CLOCK LOW; L TO R; HE'S PROBABLY ON THE VOR-A INTO TETERBORO.' IT BECAME APPARENT THERE WAS GOING TO BE A CONFLICT AND AS I WAS ABOUT TO DIRECT THE FO TO LEVEL OFF ATC SAID 'ACR X CLB BACK TO 5000 IMMEDIATELY' (WE WERE AT 4400 FT AT THE TIME). I RESPONDED 'CLBING BACK TO 5000 FT; YOU GAVE US 3000 FT.' HE RETORTED 'I GAVE YOU 5 THOUSAND.' WE CLBED BACK TO 5000 FT; THE GULFSTREAM PASSED ABOUT A HALF MI OR SO IN FRONT OF US AND BELOW. BOTH MYSELF AND THE FO CONFIRMED WE HAD BEEN GIVEN 3000 FT AS A CLRNC. THERE WAS NO DOUBT IN OUR MINDS. THERE WAS NO TCAS RA AND NO EVASIVE VECTORS ISSUED. THERE WERE NO DISTRS IN THE COCKPIT; AND WE WERE WELL RESTED. ATC; HOWEVER; SEEMED VERY BUSY INDEED. ON THE HUMAN FACTORS NOTE; THERE IS AN ENDEMIC PROB ARISING IN THE ATC SYS. IT IS MY IMPRESSION THAT OF LATE THE NYC AND ORD APCHS ARE TRYING TO CRAM EVEN MORE AIRPLANES INTO THE ALREADY OVERCROWDED AIRSPACE; AND SAFETY IS STARTING TO BE COMPROMISED AS MISTAKES ARE MADE; SEPARATION STANDARDS REDUCED; AND READBACKS UNHEARD. RATHER THAN LOOK AT WHAT WE CAN DO TO MAKE THE PARTIES PERFORM BETTER (THEY ARE ALREADY PERFORMING BEYOND EXPECTATIONS) WE SHOULD LOOK AT THE STRUCTURE OF THE PROB; AND START REDUCING THE NUMBER OF AIRPLANES IN THE SYS AT THE BUSIER ARPTS. WE SIMPLY DO NOT HAVE THE REAL ESTATE AVAILABLE; AND NO AMOUNT OF TECHNOLOGY WILL USURP THE PHYSICAL LAWS CONSTRAINING AIRPLANES FLYING CLOSELY TOGETHER IN THE ATMOSPHERE.

Data retrieved from NASA's ASRS site as of January 2009 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.