Aircraft changed frequency without authorization resulting in a conflict with another aircraft.

Attributes
ACN	123245
Time
Date	198909
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : bos
State Reference	MA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Light Transport, Low Wing, 2 Turboprop Eng
Flight Phase	ground other : taxi
Flight Plan	IFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
ASRS Report	123245
Person 2
Affiliation	government : faa
Function	controller : ground
Qualification	controller : non radar
Events
Anomaly	incursion : runway non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Intra Facility Coordination Failure Pilot Deviation

Narrative:

Pilot was issued and acknowledged hold short instructions by the local controller. He then switched to ground control frequency without authorization. Believing the pilot had clearance to cross the runway, the ground controller issued taxi instructions to the ramp.

Original NASA ASRS Text

Title: ACFT CHANGED FREQ WITHOUT AUTHORIZATION RESULTING IN A CONFLICT WITH ANOTHER ACFT.

Narrative: PLT WAS ISSUED AND ACKNOWLEDGED HOLD SHORT INSTRUCTIONS BY THE LCL CTLR. HE THEN SWITCHED TO GND CTL FREQ WITHOUT AUTHORIZATION. BELIEVING THE PLT HAD CLRNC TO CROSS THE RWY, THE GND CTLR ISSUED TAXI INSTRUCTIONS TO THE RAMP.

Data retrieved from NASA's ASRS site as of August 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.