Narrative:

I was on approach to runway 21 at cho and in contact with cho tower. Location at time of incident was 2.5 mn from threshold of runway 21, abeam piney mtn (west of mtn) at 1800 ft. Flight visibility was 4-5 mi in haze. Commercial traffic from washington area (an mdt) came on tower frequency and asked tower if he was #1 or #2 behind me. Tower replied that he was probably #2, but to standby. Tower called me and asked my position. As I was keying microphone to reply, mdt passed overhead (from behind) on approach to cho. I estimate shortest distance between our two aircraft was approximately 200 ft vertically. Mdt flight apparently never saw my aircraft, at least did not acknowledge my presence. I called tower, stated that a commuter mdt flight had just passed overhead and that I was performing a right hand 360 degree turn for spacing. After completing turn and establishing approach, continue to land without further incident. My understanding is that incoming IFR flts to cho are not to descend below 4000 ft until after contacting cho tower. The commuter flight was not cleared to any altitude by cho tower. Let alone to descend below 4000 ft. Cho has no radar and requires ample opportunity to sequence IFR and local VFR traffic, especially in conditions of restr visibility. During subsequent hour after this incident, I was in cho tower and heard another inbound IFR aircraft make initial contact with cho tower at 3000 ft. In my opinion, the current ATC procedures at cho (or the violation of these procedures) is an invitation for a fatal accident. The '4000 ft' rule strikes me as a good one if followed, but it is apparently not being observed. Cho has a standard 5 mi air traffic area, and IFR aircraft should be in contact with cho tower well before penetrating that airspace horizontally, which I am under the impression they are not doing, as well as breaking the 4000 ft ceiling.

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Original NASA ASRS Text

Title: CLOSE PROX GA SMA COMMUTER MDT IN CHO ATA.

Narrative: I WAS ON APCH TO RWY 21 AT CHO AND IN CONTACT WITH CHO TWR. LOCATION AT TIME OF INCIDENT WAS 2.5 MN FROM THRESHOLD OF RWY 21, ABEAM PINEY MTN (WEST OF MTN) AT 1800 FT. FLT VISIBILITY WAS 4-5 MI IN HAZE. COMMERCIAL TFC FROM WASHINGTON AREA (AN MDT) CAME ON TWR FREQ AND ASKED TWR IF HE WAS #1 OR #2 BEHIND ME. TWR REPLIED THAT HE WAS PROBABLY #2, BUT TO STANDBY. TWR CALLED ME AND ASKED MY POS. AS I WAS KEYING MIC TO REPLY, MDT PASSED OVERHEAD (FROM BEHIND) ON APCH TO CHO. I ESTIMATE SHORTEST DISTANCE BTWN OUR TWO ACFT WAS APPROX 200 FT VERTICALLY. MDT FLT APPARENTLY NEVER SAW MY ACFT, AT LEAST DID NOT ACKNOWLEDGE MY PRESENCE. I CALLED TWR, STATED THAT A COMMUTER MDT FLT HAD JUST PASSED OVERHEAD AND THAT I WAS PERFORMING A R HAND 360 DEG TURN FOR SPACING. AFTER COMPLETING TURN AND ESTABLISHING APCH, CONTINUE TO LAND WITHOUT FURTHER INCIDENT. MY UNDERSTANDING IS THAT INCOMING IFR FLTS TO CHO ARE NOT TO DSND BELOW 4000 FT UNTIL AFTER CONTACTING CHO TWR. THE COMMUTER FLT WAS NOT CLRED TO ANY ALT BY CHO TWR. LET ALONE TO DSND BELOW 4000 FT. CHO HAS NO RADAR AND REQUIRES AMPLE OPPORTUNITY TO SEQUENCE IFR AND LCL VFR TFC, ESPECIALLY IN CONDITIONS OF RESTR VISIBILITY. DURING SUBSEQUENT HR AFTER THIS INCIDENT, I WAS IN CHO TWR AND HEARD ANOTHER INBND IFR ACFT MAKE INITIAL CONTACT WITH CHO TWR AT 3000 FT. IN MY OPINION, THE CURRENT ATC PROCS AT CHO (OR THE VIOLATION OF THESE PROCS) IS AN INVITATION FOR A FATAL ACCIDENT. THE '4000 FT' RULE STRIKES ME AS A GOOD ONE IF FOLLOWED, BUT IT IS APPARENTLY NOT BEING OBSERVED. CHO HAS A STANDARD 5 MI ATA, AND IFR ACFT SHOULD BE IN CONTACT WITH CHO TWR WELL BEFORE PENETRATING THAT AIRSPACE HORIZLY, WHICH I AM UNDER THE IMPRESSION THEY ARE NOT DOING, AS WELL AS BREAKING THE 4000 FT CEILING.

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.