Narrative:

IFR flight plan VFR conditions 41000 ft stj to lit. 90 mi northwest of lit clearance received 'lear, descend to FL270 pilot's discretion 240.' while in descent, mep controller said 'lear, let's make it pilot's discretion 290.' my copilot replied 'pilot's discretion 290.' both of us thinking controller was being helpful by relieving the 270 restriction, left 24000 ft in altitude alert and continued descent. Mep controller gave us a 20 degree left turn. Air carrier Y announced he was deviating due (I think) RA. Center said lear jet is at 290. I looked at altimeter, it showed 28500 ft. Now knowing center thought I was at 290, started climb to FL290 and I called center stating 'I thought my clearance limit was 240.' controller asked air carrier Y how much he had deviated. Air carrier 'about 100 ft.' after landing at lit, tower asked us to call approach control when we parked. Called, approach answered advising me ZME had called to say they were investigating a pilot deviation involving us. If I wanted more information he gave me ZME's phone number. I called and talked with mr. X. He said they had pulled the tapes but hadn't reviewed them yet. I could call back in 1 hour, which I did. Mr. X wasn't available, but lady who answered said my clearance was 290 and they would be processing violation action. Naturally, I've thought about this a great deal and feel most pilots would have thought their clearance was FL240. As to how this could have been avoided? If mep controller used proper phraseology the clearance would have been much clearer. 'Traffic at 280 maintain 290.' 'cancel previous clearance maintain 290.' 'maintain 290' or if we had installed a TCA D or TCASII which would have made me aware of the 280 traffic or be clairvoyant!

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Original NASA ASRS Text

Title: ALT BUST.

Narrative: IFR FLT PLAN VFR CONDITIONS 41000 FT STJ TO LIT. 90 MI NW OF LIT CLRNC RECEIVED 'LEAR, DSND TO FL270 PLT'S DISCRETION 240.' WHILE IN DSCNT, MEP CTLR SAID 'LEAR, LET'S MAKE IT PLT'S DISCRETION 290.' MY COPLT REPLIED 'PLT'S DISCRETION 290.' BOTH OF US THINKING CTLR WAS BEING HELPFUL BY RELIEVING THE 270 RESTRICTION, LEFT 24000 FT IN ALT ALERT AND CONTINUED DSCNT. MEP CTLR GAVE US A 20 DEG L TURN. ACR Y ANNOUNCED HE WAS DEVIATING DUE (I THINK) RA. CTR SAID LEAR JET IS AT 290. I LOOKED AT ALTIMETER, IT SHOWED 28500 FT. NOW KNOWING CTR THOUGHT I WAS AT 290, STARTED CLB TO FL290 AND I CALLED CTR STATING 'I THOUGHT MY CLRNC LIMIT WAS 240.' CTLR ASKED ACR Y HOW MUCH HE HAD DEVIATED. ACR 'ABOUT 100 FT.' AFTER LNDG AT LIT, TWR ASKED US TO CALL APCH CTL WHEN WE PARKED. CALLED, APCH ANSWERED ADVISING ME ZME HAD CALLED TO SAY THEY WERE INVESTIGATING A PLTDEV INVOLVING US. IF I WANTED MORE INFO HE GAVE ME ZME'S PHONE NUMBER. I CALLED AND TALKED WITH MR. X. HE SAID THEY HAD PULLED THE TAPES BUT HADN'T REVIEWED THEM YET. I COULD CALL BACK IN 1 HR, WHICH I DID. MR. X WASN'T AVAILABLE, BUT LADY WHO ANSWERED SAID MY CLRNC WAS 290 AND THEY WOULD BE PROCESSING VIOLATION ACTION. NATURALLY, I'VE THOUGHT ABOUT THIS A GREAT DEAL AND FEEL MOST PLTS WOULD HAVE THOUGHT THEIR CLRNC WAS FL240. AS TO HOW THIS COULD HAVE BEEN AVOIDED? IF MEP CTLR USED PROPER PHRASEOLOGY THE CLRNC WOULD HAVE BEEN MUCH CLEARER. 'TFC AT 280 MAINTAIN 290.' 'CANCEL PREVIOUS CLRNC MAINTAIN 290.' 'MAINTAIN 290' OR IF WE HAD INSTALLED A TCA D OR TCASII WHICH WOULD HAVE MADE ME AWARE OF THE 280 TFC OR BE CLAIRVOYANT!

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.