ZJX controller described a stressful event when traffic at FL340 and traffic immediately below at FL...

Narrative:

I had a lear jet level at FL320 and he was looking for higher. There was an air carrier directly above the lear at FL340. It was a busy sector with aircraft deviating for weather and I was trying to climb and descend aircraft at the same time. All of a sudden the lear jet showed an altitude of FL335 and I thought the aircraft was climbing; so I asked him to say altitude and he did not respond. I then tried to turn the air carrier aircraft 50 degrees to the right but he would not turn due to weather so I climbed him to FL360. I then went back to the lear jet and asked if he was level at FL320 and he reported level. It ended up being a mode-C swap. I thought I was going to have a mid air collision. It was a terrible time for a mode-C swap to happen considering the traffic volume and unusual situations going on at the sector. I strongly believe that mode-C's transposing is a huge factor especially in my situation. I feel this problem somehow needs to be addressed. This situation could have escalated and made a worse problem.

Original NASA ASRS Text

Title: ZJX Controller described a stressful event when traffic at FL340 and traffic immediately below at FL320 swapped Mode-C information; indicating a climb initiated by the aircraft at FL320; the reporter indicating Mode-C swaps are problem.

Narrative: I had a Lear Jet level at FL320 and he was looking for higher. There was an air carrier directly above the Lear at FL340. It was a busy sector with aircraft deviating for weather and I was trying to climb and descend aircraft at the same time. All of a sudden the Lear Jet showed an altitude of FL335 and I thought the aircraft was climbing; so I asked him to say altitude and he did not respond. I then tried to turn the air carrier aircraft 50 degrees to the right but he would not turn due to weather so I climbed him to FL360. I then went back to the Lear Jet and asked if he was level at FL320 and he reported level. It ended up being a Mode-C swap. I thought I was going to have a mid air collision. It was a terrible time for a Mode-C swap to happen considering the traffic volume and unusual situations going on at the sector. I strongly believe that Mode-C's transposing is a huge factor especially in my situation. I feel this problem somehow needs to be addressed. This situation could have escalated and made a worse problem.

Data retrieved from NASA's ASRS site as of April 2012 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.

Attributes
ACN	900115
Time
Date	201007
Local Time Of Day	1801-2400
Place
Locale Reference	ZJX.ARTCC
State Reference	FL
Aircraft 1
Make Model Name	Bombardier Learjet Undifferentiated or Other Model
Flight Phase	Cruise
Route In Use	None
Flight Plan	IFR
Aircraft 2
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Cruise
Person 1
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	ATC Issue All Types

ZJX controller described a stressful event when traffic at FL340 and traffic immediately below at FL320 swapped mode-C information; indicating a climb initiated by the aircraft at FL320; the reporter indicating mode-C swaps are problem.