Air carrier cleared to land on occupied runway. Operational error.

Attributes
ACN	105523
Time
Date	198903
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : bil
State Reference	MT
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Operator	common carrier : air taxi
Make Model Name	Small Transport, Low Wing, 2 Turboprop Eng
Flight Phase	ground other : taxi landing other
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Large Transport, Low Wing, 3 Turbojet Eng
Flight Phase	landing other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
ASRS Report	105523
Person 2
Affiliation	government : faa
Function	controller : ground
Qualification	controller : non radar
Events
Anomaly	conflict : ground less severe incursion : runway non adherence : required legal separation
Independent Detector	other other : unspecified atc
Resolutory Action	none taken : anomaly accepted
Consequence	faa : investigated
Miss Distance	horizontal : 6000 vertical : 0
Supplementary
Primary Problem	Ambiguous
Air Traffic Incident	Operational Error other

Narrative:

Air carrier Y on final, atx X rolling out. It was apparent the X would make it off the runway at A3 intersection before Y would land. X switched to ground before exiting, then told ground he could not get off the runway due to a snow berm. When local realized there was a problem, air carrier Y was short final, not visible on the BRITE or visually (visibility was 3/4 mi) from the tower. In the judgement of the local controller, it was safer to let air carrier Y land, and expedite atx X to the next intersection (A2). Both aircraft were on the runway at same time. City snow plows had effectively closed the last 2 available intxns with snow berms while plowing alpha taxiway. Snow berms not discernable from the tower, nor was tower informed that there would be any problems with propeller aircraft exiting the runway. If an intersection is open, and ATC is planning traffic for those intxns, it is imperative that snow plow operations keep those intxns clear while doing operations other than runway plowing.

Original NASA ASRS Text

Title: ACR CLEARED TO LAND ON OCCUPIED RWY. OPERATIONAL ERROR.

Narrative: ACR Y ON FINAL, ATX X ROLLING OUT. IT WAS APPARENT THE X WOULD MAKE IT OFF THE RWY AT A3 INTXN BEFORE Y WOULD LAND. X SWITCHED TO GND BEFORE EXITING, THEN TOLD GND HE COULD NOT GET OFF THE RWY DUE TO A SNOW BERM. WHEN LCL REALIZED THERE WAS A PROB, ACR Y WAS SHORT FINAL, NOT VISIBLE ON THE BRITE OR VISUALLY (VISIBILITY WAS 3/4 MI) FROM THE TWR. IN THE JUDGEMENT OF THE LCL CTLR, IT WAS SAFER TO LET ACR Y LAND, AND EXPEDITE ATX X TO THE NEXT INTXN (A2). BOTH ACFT WERE ON THE RWY AT SAME TIME. CITY SNOW PLOWS HAD EFFECTIVELY CLOSED THE LAST 2 AVAILABLE INTXNS WITH SNOW BERMS WHILE PLOWING ALPHA TXWY. SNOW BERMS NOT DISCERNABLE FROM THE TWR, NOR WAS TWR INFORMED THAT THERE WOULD BE ANY PROBS WITH PROP ACFT EXITING THE RWY. IF AN INTXN IS OPEN, AND ATC IS PLANNING TFC FOR THOSE INTXNS, IT IS IMPERATIVE THAT SNOW PLOW OPS KEEP THOSE INTXNS CLR WHILE DOING OPS OTHER THAN RWY PLOWING.

Data retrieved from NASA's ASRS site as of August 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.