A C175 pilot thought he had clearance for takeoff when, in fact, he did not at myf.

Attributes
ACN	495728
Time
Date	200012
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : myf.airport
State Reference	CA
Altitude	agl single value : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : myf.tower
Operator	general aviation : personal
Make Model Name	Skylark 175
Operating Under FAR Part	Part 91
Flight Phase	climbout : takeoff
Flight Plan	VFR
Aircraft 2
Controlling Facilities	tower : mye.tower
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	landing : go around
Person 1
Affiliation	other
Function	flight crew : single pilot
Qualification	pilot : multi engine pilot : instrument pilot : cfi pilot : atp
Experience	flight time last 90 days : 7.6 flight time total : 3413 flight time type : 1200
ASRS Report	595728
Person 2
Affiliation	other
Function	flight crew : single pilot
Events
Anomaly	incursion : runway non adherence : clearance non adherence : far non adherence : published procedure
Independent Detector	other controllera
Resolutory Action	flight crew : executed go around none taken : insufficient time
Consequence	other Other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Dec/xa/00 I was making a local flight with departure from montgomery airport, san diego, ca, about XA09. I have a new portable intercom in my C175 and it was ingesting noise into the radio system so that I was having difficulty communicating with the tower. I should have returned to base. But, instead, I thought I had clearance for takeoff when, in fact, I did not. As a result, I caused the tower to order a go around for another aircraft.

Original NASA ASRS Text

Title: A C175 PLT THOUGHT HE HAD CLRNC FOR TKOF WHEN, IN FACT, HE DID NOT AT MYF.

Narrative: DEC/XA/00 I WAS MAKING A LCL FLT WITH DEP FROM MONTGOMERY ARPT, SAN DIEGO, CA, ABOUT XA09. I HAVE A NEW PORTABLE INTERCOM IN MY C175 AND IT WAS INGESTING NOISE INTO THE RADIO SYS SO THAT I WAS HAVING DIFFICULTY COMMUNICATING WITH THE TWR. I SHOULD HAVE RETURNED TO BASE. BUT, INSTEAD, I THOUGHT I HAD CLRNC FOR TKOF WHEN, IN FACT, I DID NOT. AS A RESULT, I CAUSED THE TWR TO ORDER A GAR FOR ANOTHER ACFT.

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.