Flight crew of a B737 on taxi in to gate has wingtip contact aft airstairs which were not parked pro...

Attributes
ACN	416041
Time
Date	199809
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : sjc
State Reference	CA
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B737 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
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 : 200 flight time total : 7000 flight time type : 2000
ASRS Report	416041
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	conflict : ground critical other anomaly other
Independent Detector	other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Air Traffic Incident	other
Situations
Airport	other physical facility procedure or policy : unspecified

Narrative:

On taxi in at sjc, under guidance and on the lead-in line, the outboard portion of the left wingtip rode over the aft moveable airstairs. The guideman gave the emergency stop signal and the aircraft was brought to a stop 15 ft short of the normal B737 stop point. The airstair remained wedged under the wingtip tilted up at a 30 degree angle. The aircraft sustained no apparent damage. On clearing the left side of the aircraft for the left turn into the gate, the airstairs, which I saw, never registered in my mind as a threat to the aircraft as they were positioned where you would expect them to be. Due to the significant length (approximately 230 ft) of the lead-in line at sjc, judging the position of the stop point relative to the stairs would be difficult and this is not something we normally do on every taxi in. I felt secure taxiing in on the yellow lead-in line and under positive control. I had seen the airstairs, and they were supposed to be there. Had it been a baggage cart, or a fuel truck, or belt loader, it probably would have registered as a threat. Unfortunately the airstairs did not. Because we taxi past airstairs on a fairly regular basis, nothing seemed out of the ordinary and because I was under guidance, my attention was focused forward on the guideman and had been since the initial turn in, instead of on the left side of the aircraft where it would have needed to be to avoid the incident. After surveying the situation after the incident it was apparent that the guideman's view of the aft airstair was blocked by the forward airstair and our staffing with procedures require only 1 guideman. Thus, he was unaware of the problem. In retrospect I should have perceived the airstairs' position as a threat. However, the geometry of ground equipment positioning is something I had previously given very little attention to.

Original NASA ASRS Text

Title: FLC OF A B737 ON TAXI IN TO GATE HAS WINGTIP CONTACT AFT AIRSTAIRS WHICH WERE NOT PARKED PROPERLY. FORWARD AIRSTAIRS BLOCKED THE AFT AIRSTAIRS' POS FROM MARSHALLER'S VIEW.

Narrative: ON TAXI IN AT SJC, UNDER GUIDANCE AND ON THE LEAD-IN LINE, THE OUTBOARD PORTION OF THE L WINGTIP RODE OVER THE AFT MOVEABLE AIRSTAIRS. THE GUIDEMAN GAVE THE EMER STOP SIGNAL AND THE ACFT WAS BROUGHT TO A STOP 15 FT SHORT OF THE NORMAL B737 STOP POINT. THE AIRSTAIR REMAINED WEDGED UNDER THE WINGTIP TILTED UP AT A 30 DEG ANGLE. THE ACFT SUSTAINED NO APPARENT DAMAGE. ON CLRING THE L SIDE OF THE ACFT FOR THE L TURN INTO THE GATE, THE AIRSTAIRS, WHICH I SAW, NEVER REGISTERED IN MY MIND AS A THREAT TO THE ACFT AS THEY WERE POSITIONED WHERE YOU WOULD EXPECT THEM TO BE. DUE TO THE SIGNIFICANT LENGTH (APPROX 230 FT) OF THE LEAD-IN LINE AT SJC, JUDGING THE POS OF THE STOP POINT RELATIVE TO THE STAIRS WOULD BE DIFFICULT AND THIS IS NOT SOMETHING WE NORMALLY DO ON EVERY TAXI IN. I FELT SECURE TAXIING IN ON THE YELLOW LEAD-IN LINE AND UNDER POSITIVE CTL. I HAD SEEN THE AIRSTAIRS, AND THEY WERE SUPPOSED TO BE THERE. HAD IT BEEN A BAGGAGE CART, OR A FUEL TRUCK, OR BELT LOADER, IT PROBABLY WOULD HAVE REGISTERED AS A THREAT. UNFORTUNATELY THE AIRSTAIRS DID NOT. BECAUSE WE TAXI PAST AIRSTAIRS ON A FAIRLY REGULAR BASIS, NOTHING SEEMED OUT OF THE ORDINARY AND BECAUSE I WAS UNDER GUIDANCE, MY ATTN WAS FOCUSED FORWARD ON THE GUIDEMAN AND HAD BEEN SINCE THE INITIAL TURN IN, INSTEAD OF ON THE L SIDE OF THE ACFT WHERE IT WOULD HAVE NEEDED TO BE TO AVOID THE INCIDENT. AFTER SURVEYING THE SIT AFTER THE INCIDENT IT WAS APPARENT THAT THE GUIDEMAN'S VIEW OF THE AFT AIRSTAIR WAS BLOCKED BY THE FORWARD AIRSTAIR AND OUR STAFFING WITH PROCS REQUIRE ONLY 1 GUIDEMAN. THUS, HE WAS UNAWARE OF THE PROB. IN RETROSPECT I SHOULD HAVE PERCEIVED THE AIRSTAIRS' POS AS A THREAT. HOWEVER, THE GEOMETRY OF GND EQUIP POSITIONING IS SOMETHING I HAD PREVIOUSLY GIVEN VERY LITTLE ATTN TO.

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.

Flight crew of a B737 on taxi in to gate has wingtip contact aft airstairs which were not parked properly. Forward airstairs blocked the aft airstairs' position from marshaller's view.