Air carrier flight crew thought cleared position and hold. Taxied onto runway.

Attributes
ACN	179906
Time
Date	199105
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dfw
State Reference	TX
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground : holding
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 10000 flight time type : 200
ASRS Report	179906
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 240 flight time total : 10000 flight time type : 1000
ASRS Report	179490
Events
Anomaly	incursion : runway other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : detected after the fact
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	ATC Human Performance
Air Traffic Incident	other

Narrative:

While holding short of runway 17R at dfw, the tower controller was busy. Both the first officer and I understood him to say position and hold behind the air carrier medium large transport. He was extremely busy giving continuous run-on instructions with no gap to allow for acknowledgements. After I taxied into position, the tower controller said, 'now you are cleared into position and hold--I told you to expect position and hold behind the air carrier medium large transport.' we stated we heard we were cleared into position. He then responded with 'I'll pull the tape.' regardless of who was correct here, this is a prime example of poor communication by the controller. If he was correct, the clearance was ambiguous and obviously easy to misinterp.

Original NASA ASRS Text

Title: ACR FLT CREW THOUGHT CLEARED POSITION AND HOLD. TAXIED ONTO RWY.

Narrative: WHILE HOLDING SHORT OF RWY 17R AT DFW, THE TWR CTLR WAS BUSY. BOTH THE F/O AND I UNDERSTOOD HIM TO SAY POS AND HOLD BEHIND THE ACR MLG. HE WAS EXTREMELY BUSY GIVING CONTINUOUS RUN-ON INSTRUCTIONS WITH NO GAP TO ALLOW FOR ACKNOWLEDGEMENTS. AFTER I TAXIED INTO POS, THE TWR CTLR SAID, 'NOW YOU ARE CLRED INTO POS AND HOLD--I TOLD YOU TO EXPECT POS AND HOLD BEHIND THE ACR MLG.' WE STATED WE HEARD WE WERE CLRED INTO POS. HE THEN RESPONDED WITH 'I'LL PULL THE TAPE.' REGARDLESS OF WHO WAS CORRECT HERE, THIS IS A PRIME EXAMPLE OF POOR COM BY THE CTLR. IF HE WAS CORRECT, THE CLRNC WAS AMBIGUOUS AND OBVIOUSLY EASY TO MISINTERP.

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.