Narrative:

Procedure at pdk is to have ground control instruct departing aircraft to 'monitor tower' then local control broadcast control instructions 'in the blind.' many times for various reasons the local controller may not know that aircraft are monitoring frequency waiting for control instructions. Confusion can result with similar sounding call signs. 2-WAY communication is established with #1 aircraft; then controller can use last 3 of n-number -- not knowing that similar sounding call sign is now monitoring. Aircraft #2 hears the last 3 of his call sign used and responds (controllers often use last 3 even on initial contact; so #2 aircraft is not concerned that controller only used last 3). Confusion or hazardous situation results. Aircraft xxabc was a departure monitoring and aircraft yyabc was inbound in contact. No loss of separation or conflicts this time; but potentially unsafe situation. Poor procedure.

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Original NASA ASRS Text

Title: PDK CTLR EXPRESSED CONCERN REGARDING LCL PROC INVOLVING DEP ACFT MONITORING LCL CTLR RATHER THAN INITIATING A CALL FOR DEP.

Narrative: PROC AT PDK IS TO HAVE GND CTL INSTRUCT DEPARTING ACFT TO 'MONITOR TWR' THEN LCL CTL BROADCAST CTL INSTRUCTIONS 'IN THE BLIND.' MANY TIMES FOR VARIOUS REASONS THE LCL CTLR MAY NOT KNOW THAT ACFT ARE MONITORING FREQ WAITING FOR CTL INSTRUCTIONS. CONFUSION CAN RESULT WITH SIMILAR SOUNDING CALL SIGNS. 2-WAY COM IS ESTABLISHED WITH #1 ACFT; THEN CTLR CAN USE LAST 3 OF N-NUMBER -- NOT KNOWING THAT SIMILAR SOUNDING CALL SIGN IS NOW MONITORING. ACFT #2 HEARS THE LAST 3 OF HIS CALL SIGN USED AND RESPONDS (CTLRS OFTEN USE LAST 3 EVEN ON INITIAL CONTACT; SO #2 ACFT IS NOT CONCERNED THAT CTLR ONLY USED LAST 3). CONFUSION OR HAZARDOUS SITUATION RESULTS. ACFT XXABC WAS A DEP MONITORING AND ACFT YYABC WAS INBOUND IN CONTACT. NO LOSS OF SEPARATION OR CONFLICTS THIS TIME; BUT POTENTIALLY UNSAFE SITUATION. POOR PROC.

Data retrieved from NASA's ASRS site as of January 2009 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.