An A300 crew departing egll witnessed another aircraft take the runway without a clearance.

Attributes
ACN	521432
Time
Date	200108
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : egll.airport
State Reference	FO
Altitude	agl single value : 0
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	A300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	ground : position and hold ground : taxi
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tower : egll.tower
Operator	common carrier : air carrier
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	ground : takeoff roll ground : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
ASRS Report	521432
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Events
Anomaly	incursion : runway non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	controller : issued advisory flight crew : took precautionary avoidance action
Consequence	faa : reviewed incident with flight crew
Supplementary
Problem Areas	Airport Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ATC facility: heathrow tower. Location: end of runway 27L. We had been cleared onto runway 27L after the first B757. He got clearance for takeoff and we started on to runway 27L and at the same time another B757 right behind the first started on to runway 27L. We stopped to ensure wingtip clearance and to confirm our clearance on to runway 27L. We had been correct and the other flight had misunderstood his clearance. Took off with no further problems.

Original NASA ASRS Text

Title: AN A300 CREW DEPARTING EGLL WITNESSED ANOTHER ACFT TAKE THE RWY WITHOUT A CLRNC.

Narrative: ATC FACILITY: HEATHROW TWR. LOCATION: END OF RWY 27L. WE HAD BEEN CLRED ONTO RWY 27L AFTER THE FIRST B757. HE GOT CLRNC FOR TKOF AND WE STARTED ON TO RWY 27L AND AT THE SAME TIME ANOTHER B757 RIGHT BEHIND THE FIRST STARTED ON TO RWY 27L. WE STOPPED TO ENSURE WINGTIP CLRNC AND TO CONFIRM OUR CLRNC ON TO RWY 27L. WE HAD BEEN CORRECT AND THE OTHER FLT HAD MISUNDERSTOOD HIS CLRNC. TOOK OFF WITH NO FURTHER PROBS.

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.