Captain of an small transport twin turboprop accidentally taxied off of taxiway leaving ramp resulti...

Attributes
ACN	334495
Time
Date	199604
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : iah
State Reference	TX
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : corporate
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Operating Under FAR Part	Part 91
Flight Phase	ground : holding ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	Other
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 20 flight time total : 4700 flight time type : 20
ASRS Report	334495
Person 2
Affiliation	Other
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

We had received clearance from clearance delivery and were moving on the ramp expecting taxi clearance. Ramp has single entrance/exit to taxiway. Hold short line is midway between ramp and airport taxiway. Clearance delivery issues 'monitor ground' clearance. We were already at hold short line awaiting taxi clearance when ground issued a notice that traffic was inbound to ramp. When we attempted to swing wide onto main taxiway, I swung too wide and dropped right wheel (main landing gear) off taxiway edge into soft ground. Wheel sunk approximately 8 inches into soft ground. Shut down with no damage, but partially blocking taxiway. Causes were moving (even on uncontrolled ramp) without taxi clearance, and failure to maintain careful position awareness of wheels in a close situation. I should have held position on ramp until taxi clearance was obtained and once it was obvious that I was blocking ramp access I should have shut down and obtained tug assistance to clear taxiway.

Original NASA ASRS Text

Title: CAPT OF AN SMT TWIN TURBOPROP ACCIDENTALLY TAXIED OFF OF TXWY LEAVING RAMP RESULTING IN THE R MAIN GEAR SINKING IN SOFT DIRT CAUSING THE ACFT TO BECOME STRANDED.

Narrative: WE HAD RECEIVED CLRNC FROM CLRNC DELIVERY AND WERE MOVING ON THE RAMP EXPECTING TAXI CLRNC. RAMP HAS SINGLE ENTRANCE/EXIT TO TXWY. HOLD SHORT LINE IS MIDWAY BTWN RAMP AND ARPT TXWY. CLRNC DELIVERY ISSUES 'MONITOR GND' CLRNC. WE WERE ALREADY AT HOLD SHORT LINE AWAITING TAXI CLRNC WHEN GND ISSUED A NOTICE THAT TFC WAS INBOUND TO RAMP. WHEN WE ATTEMPTED TO SWING WIDE ONTO MAIN TXWY, I SWUNG TOO WIDE AND DROPPED R WHEEL (MAIN LNDG GEAR) OFF TXWY EDGE INTO SOFT GND. WHEEL SUNK APPROX 8 INCHES INTO SOFT GND. SHUT DOWN WITH NO DAMAGE, BUT PARTIALLY BLOCKING TXWY. CAUSES WERE MOVING (EVEN ON UNCTLED RAMP) WITHOUT TAXI CLRNC, AND FAILURE TO MAINTAIN CAREFUL POS AWARENESS OF WHEELS IN A CLOSE SIT. I SHOULD HAVE HELD POS ON RAMP UNTIL TAXI CLRNC WAS OBTAINED AND ONCE IT WAS OBVIOUS THAT I WAS BLOCKING RAMP ACCESS I SHOULD HAVE SHUT DOWN AND OBTAINED TUG ASSISTANCE TO CLR TXWY.

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.

Captain of an small transport twin turboprop accidentally taxied off of taxiway leaving ramp resulting in the right main gear sinking in soft dirt causing the aircraft to become stranded.