Friday, May 28, 2010

Near midair collision between US Airways A319 and Cargolux B747 at Anchorage

by B. N. Sullivan

NTSB logoThe U.S. National Transportation Safety Board (NTSB) announced today that it has begun an investigation into a near midair collision between a commercial airliner and a widebody cargo plane at Anchorage a week ago. The incident involved an Airbus A319-100 operated by US Airways, and a Boeing B747-400 freighter operated by Cargolux. The A319 had 138 people on board; the freighter had a crew of two. No one was injured.

According to the NTSB, the incident occurred shortly after midnight on May 21, 2010. US Airways flight USA140 was arriving at Anchorage International Airport (ANC) from Phoenix, and Cargolux Airlines International flight CLX658 was departing ANC for Chicago-O'Hare. The US Airways plane was on approach to runway 14 at ANC when the crew executed a go-around. The Cargolux freighter was departing runway 25R. The NTSB says the two aircraft "came within an estimated 100 feet vertically and a .33 mile lateral separation."

From the NTSB statement announcing the investigation of the incident:
According to the TCAS report from the A319 crew, that aircraft was approaching ANC when, because of the effects of tailwinds on the aircraft's approach path, the crew initiated a missed approach and requested new instructions from air traffic control. The tower controller instructed the A319 to turn right heading 300 and report the departing B747 in sight.

After the A319 crew reported the B747 in sight, the controller instructed the A319 to maintain visual separation from the B747, climb to 3000 feet, and turn right heading 320. The A319 crew refused the right turn because the turn would have put their flight in direct conflict with the B747.

The A319 crew then received a resolution advisory to "monitor vertical speed" and the crew complied with the descent command. During the descent, the A319 crew lost sight of the B747. At about 1700 feet above ground level, the A319 crew received a "clear of conflict" aural command.
The NTSB notes that the incident occurred in night visual meteorological conditions with 10 miles of visibility.