NTSB ADVISORY
National Transportation Safety Board
Washington, DC 20594
March 30, 2010
NTSB INVESTIGATING NEAR MID-AIR COLLISION OVER SAN FRANCISCO
INVOLVING COMMERCIAL JETLINER AND SMALL PLANE
The NTSB has launched an investigation to determine why a
commercial jetliner and a small light airplane came within
an estimated 300 feet of colliding over San Francisco on
Saturday.
At about 11:15 a.m. PDT on March 27, the crew of United
Airlines Flight 889, a B777-222 (N216UA) destined for
Beijing, China, carrying 251 passengers and a crew of 17,
was cleared to takeoff from San Francisco International
Airport (SFO) on runway 28L and climb to an initial altitude
of 3,000 feet. The first officer, who was flying the
aircraft, reported that after the landing gear was retracted
and the jet was at an altitude of about 1,100 feet, the
tower controller reported traffic at his 1 o’clock position.
Immediately following the controller’s advisory, the
airplane’s traffic collision avoidance system (TCAS) issued
an audible alert of “TRAFFIC TRAFFIC.”
The pilots saw a light high wing airplane, an Aeronca 11AC
(N9270E), in a hard left turn traveling from their 1 o’clock
to 3 o’clock position. The first officer pushed the control
column forward to level the airplane. Both crew members
reported seeing only the underside of the Aeronca as it
passed to within an estimated 200-300 feet of the 777.
TCAS then issued an “ADJUST VERTICAL SPEED” alert, followed
by a “DESCEND, DESCEND” alert. The first officer complied
and the flight continued to Beijing without further
incident.
NTSB investigator Scott Dunham is traveling to San Francisco
to begin the investigation.