Will Hold 'En Banc' Hearing In May Regarding Into February 12
Downing Near Buffalo
The
National Transportation Safety Board announced Wednesday it will
hold a three-day public hearing into the events surrounding the
February 12 downing of Colgan Air Flight 3407 in Clarence Center,
NY. The "en banc" hearing -- meaning all NTSB Members will sit on
the Board of Inquiry -- will be conducted May 12-14 in Washington,
DC.
"The tragedy of flight 3407 is the deadliest transportation
accident in the United States in more than 7 years," Acting
Chairman Mark V. Rosenker, who will chair the hearing, said. "The
circumstances of the crash have raised several issues that go well
beyond the widely discussed matter of airframe icing, and we will
explore these issues in our investigative fact-finding
hearing."
The NTSB also issued the following update on the investigation
into the fatal crash that claimed the lives of the 49 persons
onboard, as well as one on the ground.
Of particular note is the Board's belief that, contrary to speculation severe airframe
icing led to the accident, that icing may have had
only a "minimal" impact on stall speed of the aircraft... and
apparent confirmation the flying pilot
apparently pulled back on the control column
when the stick shaker activated, warning the crew of an impending
stall condition:
The aircraft wreckage has been moved
from the accident site to a secure location for follow-on
inspections as may be needed.
A preliminary examination of the
airplane systems has revealed no indication of pre-impact system
failures or anomalies. Investigators will perform additional
examinations on the dual distribution valves installed in the
airplane's de-ice system. The de-ice system removes ice
accumulation from the leading edges of the wings, horizontal tail,
and vertical tail through the use of pneumatic boots. The dual
distribution valves, which transfer air between the main bleed air
distribution ducts and the pneumatic boots, were removed from the
airplane for the examination. The airplane maintenance records have
been reviewed and no significant findings have been identified at
this time. The ATC group has completed a review of recordings of
controller communications with the flight crew during the accident
flight and conducted interviews with air traffic controllers on
duty at the time of the accident. The group has no further work
planned at this time.
Further review of the weather
conditions on the night of the accident revealed the presence of
variable periods of snow and light to moderate icing during the
accident airplane's approach to the Buffalo airport.
Examination of the FDR data and preliminary evaluation of
airplane performance models shows that some ice accumulation was
likely present on the airplane prior to the initial upset event,
but that the airplane continued to respond as expected to flight
control inputs throughout the accident flight. The FDR data also
shows that the stall warning and protection system, which includes
the stick shaker and stick pusher, activated at an airspeed and
angle-of-attack (AOA) consistent with that expected for normal
operations when the de-ice protection system is active. The
airplane's stick shaker will normally activate several knots above
the actual airplane stall speed in order to provide the flight crew
with a sufficient safety margin and time to initiate stall recovery
procedures. As a result of ice accumulation on the airframe, an
airplane's stall airspeed increases. To account for this potential
increase in stall speed in icing conditions, the Dash 8-Q400's
stall warning system activates at a higher airspeed than normal
when the de-ice system is active in-flight to provide the flight
crew with adequate stall warning if ice accumulation is
present.
Preliminary airplane performance
modeling and simulation efforts indicate that icing had a minimal
impact on the stall speed of the airplane. The FDR data indicates
that the stick shaker activated at 130 knots, which is consistent
with the de-ice system being engaged. FDR data further indicate
that when the stick shaker activated, there was a 25-pound pull
force on the control column, followed by an up elevator deflection
and increase in pitch, angle of attack, and Gs. The data indicate a
likely separation of the airflow over the wing and ensuing roll two
seconds after the stick shaker activated while the aircraft was
slowing through 125 knots and while at a flight load of 1.42 Gs.The
predicted stall speed at a load factor of 1 G would be about 105
knots.
Airplane performance work is
continuing. Since returning from on-scene, the Operations &
Human Performance group has conducted additional interviews with
flight crew members who had recently flown with and/or provided
instruction to the accident crew, as well as personnel at Colgan
Air responsible for providing training of flight crews and
overseeing the management and safety operations at the airline. The
group also conducted interviews with FAA personnel responsible for
oversight of the Colgan certificate, which included the Principal
Operations Inspector (POI) and aircrew program manager for the Dash
8 Q-400. The team has also continued its review of documentation,
manuals, and other guidance pertaining to the operation of the Dash
8 Q-400 and training materials provided to the Colgan Air flight
crews.
The Operations & Human Performance
group continues to investigate and review documentation associated
with the flight crew's flight training history and professional
development during their employment at Colgan as well as prior to
joining the company.
Post-accident toxicological testing of
the flight crew was performed by the FAA Civil Aerospace Medical
Institute (CAMI) toxicology lab. Specimens taken from the first
officer were negative for alcohol, illicit substances, and a wide
range of prescription and over the counter medications. Specimens
taken from the captain were negative for alcohol and illicit
substances, and positive for diltiazem, a prescription blood
pressure medication that had been reported to and approved for his
use by the Federal Aviation Administration.
The Safety Board is also examining
several other areas potentially related to the accident,
including:
- The circumstances of a recent event involving a Dash 8-Q400,
operated by Colgan Air, in which the airplane's stick shaker
activated during approach to the Burlington International Airport
(BTV) in Burlington, Vermont. A preliminary review of the FDR data
from that flight shows the momentary onset of the stick shaker
during the approach phase of flight. The airplane subsequently
landed without incident. NTSB investigators have conducted
interviews with the pilots and check airman on board this flight
and will continue to investigate the incident.
- Reports of airplane deviations resulting from distortion of the
instrument landing system (ILS) signal for runway 23 at BUF. There
is an existing Notice to Airmen (NOTAM) related to this distortion
condition. To date, investigation into these reports has not
revealed any connection to the accident flight.