Flight crew of lear 35 misinterprets taxi clearance and taxies on runway without clearance.

Attributes
ACN	366145
Time
Date	199704
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : yip
State Reference	MI
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : mdw
Operator	common carrier : air carrier
Make Model Name	Learjet 35
Operating Under FAR Part	other : unknown
Flight Phase	ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 250 flight time total : 5500 flight time type : 3200
ASRS Report	366145
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While taxiing for takeoff on taxiway that joins intended takeoff runway midfield, clearance was given to taxi to the intended runway. Part of ground's transmission was stepped on. We read back 'understand cleared to taxi into position.' no response from tower followed. After taxiing back on runway, ground advised us that we had not been given clearance to taxi back on runway, only to taxi to runway but to hold short. We admitted to ground that we had made a mistake. Ground advised us that there was no conflicting traffic. The takeoff and rest of flight went normal. Normally, ground advises to call tower holding short of runway. Since this was not the case this day and our transmission that we thought we were cleared to back taxi, followed by no response, might have added to our confusion. Ultimately, the cause of the incursion was our failure to adhere to the clearance given and not to insist for clarification.

Original NASA ASRS Text

Title: FLC OF LEAR 35 MISINTERPRETS TAXI CLRNC AND TAXIES ON RWY WITHOUT CLRNC.

Narrative: WHILE TAXIING FOR TKOF ON TXWY THAT JOINS INTENDED TKOF RWY MIDFIELD, CLRNC WAS GIVEN TO TAXI TO THE INTENDED RWY. PART OF GND'S XMISSION WAS STEPPED ON. WE READ BACK 'UNDERSTAND CLRED TO TAXI INTO POS.' NO RESPONSE FROM TWR FOLLOWED. AFTER TAXIING BACK ON RWY, GND ADVISED US THAT WE HAD NOT BEEN GIVEN CLRNC TO TAXI BACK ON RWY, ONLY TO TAXI TO RWY BUT TO HOLD SHORT. WE ADMITTED TO GND THAT WE HAD MADE A MISTAKE. GND ADVISED US THAT THERE WAS NO CONFLICTING TFC. THE TKOF AND REST OF FLT WENT NORMAL. NORMALLY, GND ADVISES TO CALL TWR HOLDING SHORT OF RWY. SINCE THIS WAS NOT THE CASE THIS DAY AND OUR XMISSION THAT WE THOUGHT WE WERE CLRED TO BACK TAXI, FOLLOWED BY NO RESPONSE, MIGHT HAVE ADDED TO OUR CONFUSION. ULTIMATELY, THE CAUSE OF THE INCURSION WAS OUR FAILURE TO ADHERE TO THE CLRNC GIVEN AND NOT TO INSIST FOR CLARIFICATION.

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.