Narrative:

Lga tower called to tell us air carrier X was making a missed approach. We told the tower to issue runway heading and maintain 2000 ft. Flight came over to me climbing through 2700 ft. I asked him to verify his altitude, he said he was expediting his descent to 2000 ft. I issued traffic at 12 O'clock and 2 mi at 2500 ft. Air carrier X didn't see the traffic. I couldn't turn the air carrier X wbound because of the MVA. The other sector controller working atx Y issued the traffic and thought air carrier X was climbing to 3000 ft. So he descended atx Y to 2000 ft. Then he observed air carrier X descending so he climbed atx Y back to 2500 ft and told him to maintain visual separation.

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Original NASA ASRS Text

Title: ACR X ON MISSED APCH CLBED THROUGH ASSIGNED ALT HAD LTSS FROM ATX Y. PLTDEV. SYS ERROR.

Narrative: LGA TWR CALLED TO TELL US ACR X WAS MAKING A MISSED APCH. WE TOLD THE TWR TO ISSUE RWY HDG AND MAINTAIN 2000 FT. FLT CAME OVER TO ME CLBING THROUGH 2700 FT. I ASKED HIM TO VERIFY HIS ALT, HE SAID HE WAS EXPEDITING HIS DSCNT TO 2000 FT. I ISSUED TFC AT 12 O'CLOCK AND 2 MI AT 2500 FT. ACR X DIDN'T SEE THE TFC. I COULDN'T TURN THE ACR X WBOUND BECAUSE OF THE MVA. THE OTHER SECTOR CTLR WORKING ATX Y ISSUED THE TFC AND THOUGHT ACR X WAS CLBING TO 3000 FT. SO HE DSNDED ATX Y TO 2000 FT. THEN HE OBSERVED ACR X DSNDING SO HE CLBED ATX Y BACK TO 2500 FT AND TOLD HIM TO MAINTAIN VISUAL SEPARATION.

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