Narrative:

Aircraft X was cleared for NDB 28 approach and told to contact tower on 8 mi final. Pilot acknowledged. Aircraft was observed crossing beacon and then reversed course. Pilot came on frequency and stated they were holding for descent and executing procedure turn (not authority/authorized as stated on approach plate). I asked pilot his intentions. He stated the student misunderstood the clearance aircraft was still eastbound. I then cleared the aircraft for the NDB 28 approach again in accordance with established procedure and phraseology (as before). I also cautioned the pilot on the potential for disaster had another aircraft been behind him. At the time I was vectoring an medium large transport for an ILS 22 approach to an intersecting runway. The moral of this story: read the approach plate--question the controller about your clearance before reversing course if you don't understand.

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Original NASA ASRS Text

Title: FLT CREW MADE PROC TURN WHEN PROC TURN WAS NOT AUTH. PLT DEVIATION.

Narrative: ACFT X WAS CLRED FOR NDB 28 APCH AND TOLD TO CONTACT TWR ON 8 MI FINAL. PLT ACKNOWLEDGED. ACFT WAS OBSERVED XING BEACON AND THEN REVERSED COURSE. PLT CAME ON FREQ AND STATED THEY WERE HOLDING FOR DSCNT AND EXECUTING PROC TURN (NOT AUTH AS STATED ON APCH PLATE). I ASKED PLT HIS INTENTIONS. HE STATED THE STUDENT MISUNDERSTOOD THE CLRNC ACFT WAS STILL EBND. I THEN CLRED THE ACFT FOR THE NDB 28 APCH AGAIN IN ACCORDANCE WITH ESTABLISHED PROC AND PHRASEOLOGY (AS BEFORE). I ALSO CAUTIONED THE PLT ON THE POTENTIAL FOR DISASTER HAD ANOTHER ACFT BEEN BEHIND HIM. AT THE TIME I WAS VECTORING AN MLG FOR AN ILS 22 APCH TO AN INTERSECTING RWY. THE MORAL OF THIS STORY: READ THE APCH PLATE--QUESTION THE CTLR ABOUT YOUR CLRNC BEFORE REVERSING COURSE IF YOU DON'T UNDERSTAND.

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.