NTSB Identification: OPS07IA001B
Incident occurred Friday, January 05, 2007 in Denver, CO
Probable Cause Approval Date: 11/30/2007
Aircraft: Airbus Industrie A-319, registration:
Injuries: 51 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

At 0728 MST (1428 UTC) a runway incursion occurred involving Key Lime Air (LYM) flight 4216, an SW4, and Frontier (FFT) flight 297, an A319, at Denver International Airport (DEN), Denver, Colorado.

At 0725:00, the DEN ground controller instructed LYM4216 to taxi to runway 34 via taxiways M and AA. According the SW4 pilot, blowing snow reduced his visibility and taxiway SC was covered with snow that prevented him from seeing the centerline lighting. As he attempted to find the centerline lighting, he saw blue taxi lights, followed them and turned onto runway 35L.

According to the recorded airport surface detection equipment (ASDE), LYM4216 entered runway 35L at taxiway M2 at 0727:06.

At 0728:10, the ground controller asked the LYM4216 pilot his location. The pilot advised he was abeam Signature. Once the controller asked his location, the pilot stated that he noticed that he was on a runway.

The First Officer of FFT297 reported, "the Captain and I were flying back to Denver from St. Louis. The weather had deteriorated in Denver so we prepared to fly a full instrument approach. We were cleared to land on runway 35L by tower. I believe we broke out of the clouds around 600 feet. The visibility conditions were ½ mile with blowing snow. We both looked down the runway and confirmed verbally to each other that the runway was clear. We didn't see the aircraft until we were about 100 to 50 feet or so above the deck. When it did come into sight, it was at least 2,000 feet down the runway. The winds combined with the prop wash from the aircraft along with blowing snow is what caused it to be obscured and out of sight. I immediately commenced a go around as soon as the aircraft was in sight. The tower was given warning from its collision avoidance system not more than a couple of seconds later."

At 0728:17, AMASS provided a aural and visual alert for an occupied runway and 4 seconds later, the tower controller instructed FFT297 to "go around". The aircraft missed colliding by approximately 50 feet.

Weather at the time of the incident was 600 overcast, 1100 broken, visibility 1/2 mile, light snow, mist, wind 030 at 12, runway visual range on runway 35L was 5,500 feet.

The National Transportation Safety Board determines the probable cause(s) of this incident to be:

The probable cause of the incident was the Key Lime Air flight 4216 pilot's inadvertant entry onto the active runway. A contributing factor to the incident was the failure of the Denver tower ground and local controllers to detect the aircraft on the airport movement area safety system (ASDE) display and issue a go-around instruction to the arrival flight crew.

Full narrative available

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