Aircraft X had less than standard separation from air carrier Y. System error.

Attributes
ACN	174335
Time
Date	199104
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : mcn
State Reference	GA
Altitude	msl bound lower : 9000 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx tracon : jax
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	descent other
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 4 controller radar : 2
ASRS Report	174335
Person 2
Affiliation	government : faa
Function	controller : flight data
Qualification	controller : non radar
Events
Anomaly	aircraft equipment problem : less severe conflict : airborne less severe non adherence : published procedure non adherence : required legal separation
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : investigated
Miss Distance	horizontal : 1000 vertical : 0
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	Operational Error Inter Facility Coordination Failure

Narrative:

Aircraft X came to me at 9000'. By LOA with jax approach, aircraft are to enter jax approach airspace at an even altitude. Aircraft X was climbed to 10000' approximately 50 mi from jax approach boundary. Computer entries were accomplished. Aircraft X mode C gave erroneous information indicating 11000'. Aircraft Y was told to stop altitude, squawk, and after verification, was reported level at 100. Air carrier Y was descended via LOA to 12000'. Both aircraft were leveled off to jax approach in a timely manner and at a level altitude. No correction was made on aircraft X equipment suffix. Aircraft X would not respond to communication changes, so after 2 attempts, jax approach was asked if they were talking with aircraft X. When they responded negatively, they were told to show the aircraft X as NORDO. 2 more attempts were made to switch aircraft X. Air carrier Y was switched. Jax approach proceeded to descend air carrier Y 10000', approximately 5 mi northeast of aircraft X. Knowing approach can use 3 mi and visibility sep, I did not feel a call to their attention was necessary. Later, jax approach controller called and asked the altitude of the aircraft and stated he showed the aircraft at 9000'. I confirmed that he was at 10000'. Shortly thereafter, aircraft X reported on frequency but could not hear any xmissions. Through relay with another aircraft, he was xferred to jax approach. It has come to my attention that an a-side trashed the new strip which would have shown the aircraft at 10000'. The fact that the aircraft went NORDO must have influenced jax approach controller to believe we would violate LOA. However, the way we called, should have shown him that we had talked to aircraft Y but could not now. It is my opinion that the whole problem was the a-side who threw away an important revision strip. This incident might have been avoided if approach later blocks displayed assigned altitude from center instead of relying on strips which when revised often are obtained after aircraft have entered our airspace.

Original NASA ASRS Text

Title: ACFT X HAD LESS THAN STANDARD SEPARATION FROM ACR Y. SYSTEM ERROR.

Narrative: ACFT X CAME TO ME AT 9000'. BY LOA WITH JAX APCH, ACFT ARE TO ENTER JAX APCH AIRSPACE AT AN EVEN ALT. ACFT X WAS CLBED TO 10000' APPROX 50 MI FROM JAX APCH BOUNDARY. COMPUTER ENTRIES WERE ACCOMPLISHED. ACFT X MODE C GAVE ERRONEOUS INFO INDICATING 11000'. ACFT Y WAS TOLD TO STOP ALT, SQUAWK, AND AFTER VERIFICATION, WAS RPTED LEVEL AT 100. ACR Y WAS DSNDED VIA LOA TO 12000'. BOTH ACFT WERE LEVELED OFF TO JAX APCH IN A TIMELY MANNER AND AT A LEVEL ALT. NO CORRECTION WAS MADE ON ACFT X EQUIP SUFFIX. ACFT X WOULD NOT RESPOND TO COM CHANGES, SO AFTER 2 ATTEMPTS, JAX APCH WAS ASKED IF THEY WERE TALKING WITH ACFT X. WHEN THEY RESPONDED NEGATIVELY, THEY WERE TOLD TO SHOW THE ACFT X AS NORDO. 2 MORE ATTEMPTS WERE MADE TO SWITCH ACFT X. ACR Y WAS SWITCHED. JAX APCH PROCEEDED TO DSND ACR Y 10000', APPROX 5 MI NE OF ACFT X. KNOWING APCH CAN USE 3 MI AND VIS SEP, I DID NOT FEEL A CALL TO THEIR ATTN WAS NECESSARY. LATER, JAX APCH CTLR CALLED AND ASKED THE ALT OF THE ACFT AND STATED HE SHOWED THE ACFT AT 9000'. I CONFIRMED THAT HE WAS AT 10000'. SHORTLY THEREAFTER, ACFT X RPTED ON FREQ BUT COULD NOT HEAR ANY XMISSIONS. THROUGH RELAY WITH ANOTHER ACFT, HE WAS XFERRED TO JAX APCH. IT HAS COME TO MY ATTN THAT AN A-SIDE TRASHED THE NEW STRIP WHICH WOULD HAVE SHOWN THE ACFT AT 10000'. THE FACT THAT THE ACFT WENT NORDO MUST HAVE INFLUENCED JAX APCH CTLR TO BELIEVE WE WOULD VIOLATE LOA. HOWEVER, THE WAY WE CALLED, SHOULD HAVE SHOWN HIM THAT WE HAD TALKED TO ACFT Y BUT COULD NOT NOW. IT IS MY OPINION THAT THE WHOLE PROB WAS THE A-SIDE WHO THREW AWAY AN IMPORTANT REVISION STRIP. THIS INCIDENT MIGHT HAVE BEEN AVOIDED IF APCH LATER BLOCKS DISPLAYED ASSIGNED ALT FROM CTR INSTEAD OF RELYING ON STRIPS WHICH WHEN REVISED OFTEN ARE OBTAINED AFTER ACFT HAVE ENTERED OUR AIRSPACE.

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.