Today we’ll look at an incident that took place almost a full year ago, on November 24th, 2020.
It was on this day that a Vietnam Airlines Airbus A321neo extended its flaps instead
of retracting its gear while departing Hanoi for Hue. Causing an overspeed warning, autopilot had
to be disconnected and immediate action was taken to attain the necessary pitch angle and airspeed.
According to The Aviation Herald, the Vietnam Airlines Airbus A321neo departed Hanoi at 07:45
for Hue on November 24th. Just after take-off, the captain (the pilot flying)
instructed the landing gear to be retracted. However,
the aircraft’s first officer (the pilot monitoring), after reading back an ATC
clearance, selected flaps from position 1 to position 3 instead of selecting the gear up.
With the flaps extended to position 3 while flying at 210 knots, the maximum speed was
reduced to 195 knots. The result of this was an overspeed warning lasting 10 seconds.
The captain then disconnected the autopilot and flight director and increased the pitch. At 3,500
feet, speed 170 knots, the captain retracted the flaps from position 3 to position 0.
This increased the minimum steady flight speed to 200 knots. However, Alpha Floor Protection
did not trigger as the criteria had not been reached. The captain returned the flap lever to
position 1, lowered the pitch angle to pick up speed, and rolled the aircraft to
the right to comply with the original ATC clearance to the designated flight path.
The crew requested to level off at 2,500 feet due to a technical problem.
At this altitude, the aircraft stabilized at 220 knots.
With flaps now retracted, the flight continued to its destination without further incident.
Airbus aircraft, in general, have five flap configurations. They are 0, 1, 2, 3, and FULL.
Changing these positions engages both the slats (front of the wing) and flaps (behind the wing).
Changing the position of the aircraft’s flaps and slats will result in a change
in the aircraft’s quote-unquote “safe airspeed”. Lowering the stall speed
will allow the aircraft to fly much slower than normal without falling out of the sky.
However, the aircraft wouldn’t be able to fly as fast, leading to a risk of overspeed warnings.
Flap position 1 (or 1+F to be specific) or 2 is most often engaged during takeoff,
while flaps 3 or flaps FULL is selected for landing. Flaps 3 may be used for take-off in
the case of a short runway or obstacle clearance. Those commenting on the incident on The Aviation
Herald’s report were quick to judge the pilot. One individual offered some insight into how
this incident could have occurred, saying: “It’s human factors mostly. Like any incident,
it’s a combination of causes. Many pilots are flying a lot less than they’d like to these days.
Mistakes are more likely because of a lack of practice. Here it seems the [Pilot flying]
commanded the gear up. Around the same time, the [Pilot monitoring] received an ATC instruction.”
The individual goes on to say that this would have added an element of distraction
leading to the error being made. Not only did the first officer, the pilot monitoring,
reach for the wrong lever, but they moved it in the wrong direction (for the phase of flight).
Here’s a question mainly for the pilots out there,
what do you think of this situation? Let us know your thoughts in the comments.