Controlled Flight Into Terrain

Yemenia A310 stalled as pilots lost 

track of altitude

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By:   DAVID KAMINSKI-MORROW LONDON

02:14 2 Jul 2013 

Source: 

Pilots of a Yemenia Airbus A310-300 stalled the aircraft during a low-
altitude recovery after failing to monitor its descent during a circling
approach to Comoros at night.

Just a single passenger among the 153 occupants survived after
the twinjet struck the water and broke up.

The slow pace of the inquiry - which has taken four years to conclude
- greatly irritated French investigators, while the accident also
immersed the carrier in a diplomatic spat with the French government.

Flight IY626 from Sana'a had been attempting an approach to Moroni's
runway 20. This required the aircraft to follow the opposite-direction
runway 02 localiser until 5.2nm from the airport's VOR-DME, then
 break left over the sea. The aircraft would then track parallel to the
runway before performing a 180° right turn to align with final approach.

Comorian investigation authority ANACM determined that the
aircraft (7O-ADJ), approaching from the south, became
established on the runway 02 localiser at 3,000ft.

Gusting tailwinds of 25kt ruled out a straight-in landing on
runway 02. But the crew repeatedly sought an update on the
wind conditions, which the inquiry interprets as "reluctance"
to resort to the circling approach and indicates that the pilots
were hoping the situation would change.

At a height of 1,390ft the aircraft, its autopilot engaged, broke
away from the localiser to begin the downwind leg of the
circling approach. The break was late, some 0.86nm beyond
 the published point.

The crew started configuring the aircraft for landing, deploying
the undercarriage and setting both slats and flaps to 15°.

But the late break and aggravating strong tailwind had taken
 the aircraft further north on the downwind leg and the inquiry
says: "It is likely that the captain [in the] left seat could not see
 the runway during this phase of flight."

While the minimum descent altitude was listed as 1,230ft the
aircraft continued to lose height. The inquiry says the crew had
 a "lack of awareness" of the altitude, possibly because they
were preoccupied with the aircraft's course and searching for
the runway in order to prepare for the final turn. It adds that
there is evidence that the crew was erroneously dialling the
altitude selector while attempting to select headings.

As the crew informed the controller that the flight was established
downwind, they received sink-rate and "pull up" alarms as the
aircraft passed below 700ft. The aircraft descended to a radio
altimeter height of just 161ft before climbing.

Despite the "pull up" alert, the crew did not follow the required
procedure. The pilots raised the landing-gear and, shortly a
fterwards, retracted the slats and flaps at an airspeed of just
179kt - some 14kt below the 193kt threshold required for clean
configuration.

The aircraft's pitch increased and triggered the angle-of-attack
 protection, setting the engine thrust to take-off power.

Cockpit-voice recordings captured sounds similar to the onset
of buffeting, a sign of an approaching stall.

Over the next 40s the aircraft reached an altitude of 1,000ft but
experienced right and left banks of nearly 40°. The inquiry says
the crew - focused on controlling the roll - did not counter the
"excessive" pitch generated by the engine thrust, "probably for
fear of pushing the aircraft downwards and hitting the sea".

ANACM says the aircraft stalled and rapidly lost height. It failed to
 recover, striking the sea 15s later. It attributes the 29 June 2009
accident to "inappropriate actions" by the pilots who, preoccupied
with the tricky approach, "probably did not have enough mental
resource" to deal with the deteriorating situation and multiple
alarms.