A pilot must understand the limitations by which automation makes our job easier.
After an eight-hour redeye flight from Puerto Plata, Expo 811 began its
descent into London’s Gatwick Airport. As we levelled off at FL090,
Gatwick director asked us to “slow to 220 knots and steer heading 080º,
downwind leg for Runway 26L.” The controller also noted “…if required,
headings at your discretion to avoid weather just south of the Gatwick
Airport.” Our weather radar did indicate narrow yellow and red bands of
activity, indicating moderate to heavy rain, due south of the airfield.
The first officer was flying and rotated the heading select knob to the
right. The aircraft gradually came around to a heading of 130º. From
our vantage point, it looked like we would pass between two of the
larger areas of weather. I had seen weather like this before and it was
nothing out of the ordinary for a brisk southern England October
morning. But this was the F/O’s first autumn flying the Boeing 767 and
he seemed nervous and a little hesitant.
As
we entered the darkening cloud layers, there was a flash of lightning
ahead of us. The F/O manoeuvred the aircraft a little farther to the
right. Gatwick director called again: “…when able, turn back to the
left, heading 090º.” As I replied to the transmission the aircraft
encountered a very short period of severe turbulence. At the same
instant, I noticed the flight instruments showing a rapidly increasing
left bank and the airspeed accelerating rapidly – 45º of bank and more
than 50 knots in a matter of a few seconds. Without any further
thought, I took control of the aircraft, levelled the wings and reduced
the thrust. As I slowly righted the 767, I asked the F/O to re-engage
the autopilot. The F/O mumbled something to the effect that “…I was
doing my best! I had the aircraft under control.” About 30 seconds
later, we blew out the other side of the weather and were in the clear.
I returned control to the First Officer and we continued on to land in
Gatwick without any further difficulty.
After we had shut down,
I asked the F/O how he felt about the approach and landing. Yet again,
he exclaimed that he had done nothing wrong. “Then how,” I queried,
“did the aircraft end up in an unusual attitude? And why were you not
doing anything about it?” The F/O seemed to be at a loss for words.
The
Boeing Flight Crew Training Manual states that a jet upset can be
defined as unintentionally exceeding the following conditions: pitch
attitudes greater than 25º nose up or 10º nose down, or bank angles
greater than 45º, or within normal parameters, but flying at airspeeds
inappropriate for the conditions.
The recovery technique is
similar for all upset scenarios, basically recognizing the upset,
reducing automation and completing the recovery. Evidently, at the same
time we encountered the brief period of severe turbulence, the F/O had
disconnected the auto-flight system without first thinking about what
was happening. The haste with which he reacted had cancelled the aural
disconnect warning before it had a chance to sound. To make matters
worse he did not state what he was doing – a tenet of good crew
resource management (CRM). Although the turbulence was a contributing
factor, as a result of his haste, he over-controlled and placed the
aircraft in an attitude, which resulted in 45º of bank escalating
rapidly and an increase of 50 knots of airspeed. This, I stated, “was
why I took control.”
Most modern transport aircraft have
excellent auto-flight systems and are quite capable of handling nearly
all types of turbulence in all phases of flight. Almost immediately
after takeoff the auto-flight can be engaged and can navigate the
aircraft right down to a fully automatic landing with minimal pilot
input. However, it is extremely important to understand the limitations
and parameters by which automation makes a pilot’s job easier. A pilot
can never be complacent.
As we discussed the arrival further, it
became apparent that the F/O had never experienced turbulence as severe
as we had encountered. He had some jet experience, but the upset was
something he had neither been trained for or even thought about until
that morning. In this case, the F/O had exacerbated the situation by
reacting with haste and not thinking about what he was doing. He was
silent thereafter. For a while, he probably thought, not another rant
from a “grizzly old captain.” Well, I’m not grizzly and I’m not old yet
– at least not for another few years. I know I have been humbled on
several occasions and have learned from that. Perhaps he was humbled
too.
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