An egll gate auto-stop parking system failed so that a ground worker had to command a B757-200 emerg...

Narrative:

Upon arriving at the gate in lhr; the captain taxied in on centerline. The proper indications of B757-200 were displayed. Initially it was working properly guiding the centerline control. About half way to the gate from the service road it posted 'slow' and otherwise seemed normal. The captain slowed but the indication never changed. At the point at which we all expected to see the countdown from 15 miles; it seemed delayed. Given that at some gates the nose of the plane comes quite close to the terminal it did not immediately raise an alarm to us that we had gone too far. As the captain slowed further due to the 'slow' indication; we saw movement by a ground worker toward an emergency panel. It got all of our attentions and we commented on it. The ground person hit the emergency stop button and we stopped. We were told we had traveled 25 feet beyond the normal stop point and the left engine stopped within 3 feet of hitting the jetway. They left the aircraft in position to investigate further why the automated park had malfunctioned. While coming inbound I was never able to determine which stop line was ours; so I did not have an additional point of reference to establish better situational awareness. The captain had stated that he had never been to heathrow.

Original NASA ASRS Text

Title: An EGLL gate auto-stop parking system failed so that a ground worker had to command a B757-200 emergency stop to prevent an engine from contacting the jetway.

Narrative: Upon arriving at the gate in LHR; the Captain taxied in on centerline. The proper indications of B757-200 were displayed. Initially it was working properly guiding the centerline control. About half way to the gate from the service road it posted 'SLOW' and otherwise seemed normal. The Captain slowed but the indication never changed. At the point at which we all expected to see the countdown from 15 miles; it seemed delayed. Given that at some gates the nose of the plane comes quite close to the terminal it did not immediately raise an alarm to us that we had gone too far. As the Captain slowed further due to the 'SLOW' indication; we saw movement by a ground worker toward an emergency panel. It got all of our attentions and we commented on it. The ground person hit the emergency stop button and we stopped. We were told we had traveled 25 feet beyond the normal stop point and the left engine stopped within 3 feet of hitting the jetway. They left the aircraft in position to investigate further why the automated park had malfunctioned. While coming inbound I was never able to determine which stop line was ours; so I did not have an additional point of reference to establish better situational awareness. The Captain had stated that he had never been to Heathrow.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1051276
Time
Date	201211
Local Time Of Day	0601-1200
Place
Locale Reference	EGLL.Airport
State Reference	FO
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	B757 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Person 1
Function	First Officer Pilot Not Flying
Experience	Flight Crew Last 90 Days 130 Flight Crew Total 10500 Flight Crew Type 5500
Events
Anomaly	Conflict Ground Conflict Critical Deviation - Procedural Published Material / Policy

An egll gate auto-stop parking system failed so that a ground worker had to command a B757-200 emergency stop to prevent an engine from contacting the jetway.