- The 13th of February 2018 was a beautiful day in San Francisco on the west coast of the United States.
The visibility was
well over 10 miles, hardly any clouds and only light winds, a perfect day for
flying, in other words.
This was exactly
what Captain Christopher Behnam thought as he was heading out towards San
Francisco Airport in the morning.
He was a tall,
distinguished 57-year-old captain with proud Iranian heritage who had,
just like me,
dreamed about becoming an airline pilot ever since he was a little boy.
Through hard work
and dedication, he had then managed to achieve this goal and work his way up
through the United Airlines organization
to the point where
he was finally a commander and a check airman on the mighty Boeing 777.
At the time of this
flight he had amassed just over 13,600 hours of total time and had,
during his career,
flown almost all of the large Boeings including the 737, 747, 757, 767 and now
the Boeing 777,
which he was
actually reasonably new on at this point with only 360 hours flown on it.
He was in a
particularly good mood this morning since he was flying over to Honolulu,
Hawaii, which was one of his absolute favorite destinations
and a route that
he'd flown loads of times over his career and was therefore very comfortable
with.
As he entered the
crew room, he soon met up with his colleague, First Officer Paul Ayers, which
he had actually never flown with before this flight.
Paul was 60 years
old and also very experienced. He had just over 11,300 hours in total
of which around
10,000 had been flown on the 777. But this was only going to be his second
flight
from San Francisco
to Honolulu since he was normally based in Washington, DC. The two pilots found
it really easy
to talk to each
other and they soon started looking through their pre-flight briefing material
and the weather looked great for the entire flight
with only some
cloudy weather expected over Honolulu at the end of the flight but everything
was well within planning requirements.
When the pre-flight
check was completed, they ordered the fuel and then they walked over to the
cabin crew to brief them about the flight.
The flight time was
expected to be around four hours and 40 minutes with only some occasional
turbulence and with 364 passengers planned.
Once everyone had
asked their questions and were ready, the whole crew then walked together out
to the gate where their shiny 777 was waiting for them.
It was an
amazing-looking machine which had been bought new by United 23 years earlier
and was now basking in the sunlight
with all sorts of
catering and fueling going on around it. Now the Boeing 777 is an absolutely
amazing aircraft
and if you've ever
had the chance to look at one up close, there's one thing that I guarantee you
will stand out,
its two gigantic
engines. These engines are going to play a very central role
in this story so
before we continue, I want to explain a little bit more about them.
The Pratt &
Whitney 4077 engines have a fan diameter of 112 inches
or 2.8 meters,
meaning that the outer diameter of the fan cowling is almost as wide
as the body of the
Boeing 737 that I fly. These enormous engines are a big reason why the airliner
has become as
popular as it is because generally, the larger the engine fan diameter is,
the more efficient
the whole engine is. And why is that then? Well, what drives an aircraft
forward is essentially
the reaction force
created by sucking air in through the front of the engines and then
accelerating it backwards.
If we want to
increase that force we either have to accelerate the same amount of air a lot
or accelerate a larger amount of air a little bit.
As jet engine
technology has become more mature, it has become clear that the second option
is way more fuel efficient
so that's why we
constantly see bigger and bigger engines being created as the bigger fans will
increase the bypass ratio,
meaning the amount
of air that flows past the engine core and therefore, the total air mass
accelerated.
But making engines
bigger also has some drawbacks. As the engines get bigger so does all of the
involved components
which means a
significantly higher weight. And at a certain point, that weight increase
will outweigh the performance
increase by the bigger fan, meaning that the engine has then reached its
maximum size.
In order to
counteract this, the engine manufacturers are always working on new designs
that will allow the components
to become lighter
and therefore enable the engines to become even bigger. In the case of the
PW-4000 series engines,
one of the
strategies used to achieve this was to hollow out the titanium alloy fan blades
and therefore
create empty chambers inside of them. Obviously this reduced the weight substantially
in the
101-centimeters-long individual fan blades but it also introduced a problem.
Since these blades
would be subjected to incredible forces during their lifespan, there needed to
be a way to inspect them on regular intervals
to make sure that
there were no fatigue cracks appearing. Now, if the blade is solid, this is
relatively easy
but if there are
hollow chambers within them, it becomes substantially more complicated to do.
Pratty &
Whitney obviously were aware of this and had been working on different ways of
doing these inspections
since the engines
were introduced back in 1984. Initially, they used ultrasound and X-ray
technology
but in 2005, they
came up with a new solution called Thermal Acoustic Imaging or TAI.
The way that worked
was by using sound energy to create vibrations inside the fan blade material
and if there was a
crack present, the surfaces inside of that crack would then start rubbing up
against each other
creating a heat signal which could be detected using a thermal sensor.
This was a
brilliant idea and relatively simple compared to other techniques so Pratt
& Whitney quickly rolled it out wide
and after that,
only if there was a positive indication on TAI would the blade be sent for
further non-destructive testing using other technologies.
But since TAI was
considered a new and emerging technology, there initially were no defined
training
and certification
regimen for the inspectors who were going to use it and there were a lot of fan
blades who needed to be inspected.
The blades who were
fitted to the aircraft in this story had gone through TAI inspections in both
2010 and 2015
and the inspectors
had noticed something looking a bit odd on one of the blades but had written it
off as an issue
with the overlaying
paint layer on that blade. Now you might ask what's the point of this check
if discrepancies
are written off without further investigations and that's a valid point but it
all becomes a little bit more clear
when you think back
on that lack of training that I mentioned earlier. You see on similar
inspections using other technologies
the required
minimum training was 40 classroom hours followed by 1,200 hours of practical
training.
But the inspectors
who was handling the inspections of these involved fan blades had only received
a total of 40 hours of practical training.
That's it. There
had been more training offered but unfortunately, the involved inspector had
not been able
to attend that
training since he was working through a huge inspection backlog at the time.
And there were also other factors like the fact that the inspections were taking place in a room where a lot of sunshine regularly came in
which could create
ghost images on the thermal scans, making the evaluations even harder to interpret.
And together all of
these factors had allowed a fan blade, number 11 on this number two engine on
the aircraft,
to develop a tiny
little crack inside the hollow space near the root of the blade.
This crack was
completely impossible to see with the naked eye but kept growing bigger and
bigger for each cycle that the engine operated.
Anyway, when the
pilots had left their bags in the cockpit the captain looked through the
technical logbook and saw that the aircraft was completely clean
with no recent technical
issues logged. After that it was time to start the pre-flight inspection which
in United Airlines
is always done by
the first officer. So he went outside and started his normal
clockwise
inspection where he checked that all of the probe covers were removed, that
there were no leaks, indications of bird strikes
or any other
damages to any of the components and he spent quite a long time checking each
engine
to make sure that
the giant fan blades had no damages on them. You see even tiny damages can cause
vibrations
and loss of thrust
so this is something that we pilots always pay attention to.
But everything
looked completely normal so he finished his walk around and then returned to
the cockpit
for the rest of the
pre-flight. At this point there were no indications of the kind of mayhem that
would soon follow
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Now let's continue the story. As the pilots arrived to the aircraft,
they had also been
met up by another colleague First Officer Ed Gagarin who wanted to ask if he
could hitch
a ride with them
back to Honolulu. He had just finished an earlier shift and was eager to get
back home
for his rest days
but he had also seen that the flight was almost fully booked so he asked if
there was any chance
that he could join
the pilots in the cockpit. Captain Behnam greeted him happily and joked
that if he was
going to sit up front, he might also have to do some work and they both
laughed,
not knowing just
how true this would actually turn out to be. Now Ed also mentioned
that he had just
completed his line training and that's a fact that will soon come to play a
very important role in this story.
In any case, whilst
First Officer Paul was out doing his walk around, Captain Behnam continued
setting up the aircraft for departure so when Paul got back
into the cockpit,
they could immediately start briefing and preparing for their departure.
At this point,
Captain Behnam also asked if Paul had any preferences on who should act as
pilot flying for the leg
and Paul answered
that he would love to do that since he wanted to get some experience on this
route.
So that's what they
decided to do and soon the lead purser popped her head into the cockpit and
advised them
that all passengers
had been boarded and that the crew was ready to go. This meant that there were
now 363 passengers
and 15 crew members
on board the aircraft. The pilots completed their last few checklists
as well as their
briefing for departure from Runway 28 Left and soon after that, First Officer
Paul requested pushback
from stand 80, they
started their engines and then taxied out towards the runway holding point.
All checks were
completed in a normal way with no anomalies noted, so at time 09:38 Pacific
standard time
after a grueling
38-minute taxi, First Officer Paul finally moved the thrust levers forward for
takeoff
and the giant
Boeing 777 started accelerating down the runway. The takeoff and initial climb
were completely
uneventful and once the gear and flaps were retracted the flights soon received
their clearance
to join their
oceanic route towards Honolulu which is actually one of the longest
uninterrupted overwater routes in the world.
There are other
routes who are longer but they all have alternate airports on islands along the
way
whilst the stretch
between San Francisco and Honolulu is just over water.
The aircraft
climbed in steps up towards its final cruise altitude of flight level 380 or
38,000 feet
and once up there,
the crew started completing their paperwork and then chit-chatted a bit between
themselves about their previous experience
and plans that they
had for the week ahead. The first three hours and 30 minutes of the flight
continued in the same standard way
with only position reports, fuel checks and ACARS messages sent regarding weather and wind
and Captain Behnam
chuckled about the fact that he had flown to Honolulu countless times in his
career so far
but he had never
seen a solid covering cloud layer stretching from 2,000 to 33,000 feet over the
islands
as they were now
planning to see. Soon they entered an area of light to moderate turbulence
and therefore asked
Honolulu control if they could descend 2,000 feet down to flight level 360 in
order to try to get out of it.
This was approved
and First Officer Paul dialed it in on the mode control panel and let the
autopilot initiate a cruise descent
the same way as he
had done thousands of times before. They were now about 200 nautical miles
northeast of Honolulu
with around 40
minutes of the flight still remaining when the crack in the number 11 fan blade
had reached a point
of no return. Within a millisecond, the giant fan blade separated
in a clean cut
about three and a half centimeters above its root. It shot outwards with an
incredible force
and almost
immediately impacted the adjoining blade which also shattered and went inwards
into the engine core raising even more havoc in there.
The number 11 fan
blade then started moving forward inside of the protective barrel and when it
hit the edges
it created multiple
high energy shock waves which ultimately exceeded the certified specifications
of the forward
inner barrel as well as the cowling. This meant that those parts soon failed
and were then
immediately ripped off the engine. This is known as a fan blade out or FBO
event
and it's something
that the engines are tested to be able to sustain during certification.
The protective
barrel directly surrounding the blades are constructed from incredibly durable
kevlar
but the forward
barrel and the aerodynamic engine cowling is not.
It later turned out
that parts of the engine inlet used during certification testing had been made
out of aluminium
which had a greater
ability to yield than deform than the carbon-fiber-reinforced polymer
that was the part
that was ultimately used in production. That was found to be one of the reasons
for the quick
destruction of the forward parts while the kevlar casing actually stayed
reasonably intact.
But when those
forward sections of the engine disappeared, parts of the fan blade which were
still spiraling forward managed
to escape the
encasement and shot straight into the side of the aircraft.
But through an
incredible act of luck, they impacted the body exactly at the place where a
stringer,
a structure apart
of the body, was located just below one of the passenger windows.
This meant that the
blade fragment didn't puncture the cabin which could have been catastrophic
for the passenger
sitting next to it and even worse, would have caused an immediate
depressurization
of the aircraft.
Luckily, that didn't happen but in the cockpit, none of the pilots had any idea
of what had just
crippled their aircraft. They only heard an enormous explosion
and then it felt
like the aircraft had literally hit a brick wall. The deceleration was so
severe
that Captain Behnam
and First Officer Ayers almost slammed their heads into their glare shield
and within one and
a half second the aircraft had lurched into a 45-degree right bank whilst also
yawing sharply
in the same
direction. This was incredibly disorienting as it all happened very fast
and literally came
from nowhere and there was no prior warning. One second they were flying along
nicely
and in the next,
their aircraft was literally snap rolling over its right wing and shaking like
it was about to break up.
Captain Behnam
being the training captain that he was, immediately realized the gravity of the
situation
and called out,
"I have controls!" He grabbed the control wheel as the autopilot and
autothrottle both disengaged
and then glanced
down onto his engine displays to confirm what he thought must be a catastrophic
engine failure.
When he did that he
saw to his amazement that the engine instruments both showed completely normal
values.
So he called out,
"What happened?" To get some help identifying the failure and First
Officer Paul Ayers just responded, "I don't know.
The engine
instruments are normal." In the corner of his eye, Captain Behnam
now also saw how
the airspeed who just a few seconds ago had been steadily at Mach 0.83 had
started slowing down rapidly
and he knew that he
now had very little time to react. Whatever this was, it was coming from the
right side
as the aircraft was
both yawing and rolling that way so he instinctively pushed left rudder
and gently gave
maximum ailerons towards the left. All he could think about
was trying to keep
the blue side up on his primary flight display whilst also pushing the left
thrust lever all the way forward
to get as much
thrust as he possibly could to slow down the deceleration. At this altitude,
it's very important
to not move the
controls too fast as that can cause Mach shock waves to form and the fact that
the aircraft
was already banking
45 degrees meant that they were already experiencing higher than normal
g-forces,
something that also
increases the aircraft's stall speed. Ed the 1st officer on the jump seat now
called out,
"Maybe we've
had an in-flight collision." Now that would definitely explain the
explosion,
extreme vibrations
and sudden loss of controls that they were now experiencing but they were at
36,000 feet
and had seen
nothing on their TCAS. There just shouldn't be anyone else at that altitude.
You see above
18,000 feet in the US, all airspace is controlled with mandatory transponder
use
so if there would
have been anyone else up there, they should have seen it.
Anyway with full
deflection on both rudder and aileron, the stricken 777 now started slowly rolling
back
towards wings level
again but with the airspeed still decreasing.
All of this, except
for the strange engine indications were typical for a severe engine failure
and captain Behnam
knew that if this was the case the aircraft would not be able to maintain its
altitude for much longer.
A twin engine jet
can, depending on type and weight, normally keep an altitude around 21,000 to
24,000 feet
on one engine but
never 36,000. This meant that he needed to start descending immediately
otherwise the aircraft
would soon stall and he could potentially completely lose control.
On top of all of
this, they were now shaking so badly that the pilots had problems focusing
their eyes enough
to see their
instruments in front of them and to reach for specific controls and meanwhile
this was happening,
a sickening sound
of twisting metal could be heard from behind them, a sound similar to what you
would hear
in a sinking
submarine as the pressure starts crushing it. 35 seconds after the start of
this nightmare
the engine
instruments for the right-hand engine suddenly started blanking one by one.
What had actually
happened was that the entire EEC, a computer in charge of reporting values to
the engine instruments had been ripped away
when the engine
cowling separated. So what the pilots had been looking at was just the last
reported values
from the engine
before the failure had occurred which had stuck in the screen's memory due to a
lack of other inputs.
This finally
confirmed to the crew that they were indeed dealing with some kind of severe
damage to the right hand engine
and Captain Behnam
therefore asked First Officer Paul to please start executing the engine severe
damage checklist
from the ECL, their
electronic checklist. In other aircraft, like the Boeing 737 that I fly,
this type of
failure includes something known as memory items, meaning items that has to be
done from memory
without reference
to a checklist. But in the 777, this instead had to be done
from their internal
electronic checklist in their EICAS. But the problem now was that the aircraft
was shaking
so badly that the
first officer simply couldn't reach to use the EICAS at all and this is where
experience once again comes in.
You see both pilots
had been operating with memory items in previous aircraft which meant that they
now could just go through them from memory.
So Paul started
reading out, "Autothrottle, confirm off."
"Off."
"Engine thrust lever, confirm close." "Close."
"Engine start
lever, confirm cut off?" "Cut off." All three pilots made sure
that they didn't rush these steps
because previous
accidents had taught them that it's very easy to misidentify a failure like
this
and end up shutting
down the wrong engine. Once these items had been completed the vibrations
subsided slightly
but were still very
bad so they all agreed to add one more point to the checklist
to pull the engine
fire switch. This step would completely isolate the right engine and shut off
all of its fuel,
oil and hydraulics. So they looked at each other,
"Number two
fire handle, confirm pull?" "Confirmed." And they pulled it.
Once this step was
done, the vibrations finally reduced from about 15 on a scale from one to 10
down to about seven
still really bad, terrifying for the passengers but now at least manageable.
Using their EICAS
and their electronic checklist was still very hard so instead Ed on the jump
seat
pulled up his iPad
and started running through the checklist verbally. Remember he was still fresh
out of training
and he was
therefore, really, really familiar with all of these checklists from his recent
sim and this turned out to be a great help.
Now here it's
probably a good idea to also look at how this crew were dividing their different
roles.
Captain Behnam was
still hand-flying the aircraft and even though he'd been able to slightly
reduce the amount of aileron and rudder input
he was still using
a lot and it took up most of his capacity to just keep the aircraft straight
and reasonably level.
Because of that, he
took full advantage of all available resources in the cockpit which included
his jump-seating colleague, Ed, who was tasked
with helping First
Officer Paul with everything that he needed including the checklists,
performance calculations and overall monitoring.
Captain Behnam made
it absolutely clear that he had very limited capacity to oversee the checklist
handling
which he would
normally do so he was concentrating on aviating and would continue to do so
for as long as it would
take. By being very clear here and by delegating effectively
the crew was able
to contain a catastrophic failure within a very quick time frame.
This serves as an
excellent example of how crew resource management is supposed to work and also
a great adherence
to the golden rule
of aviation: aviate, navigate, communicate.
This meant that the
next step was to navigate and communicate.
Captain Behnam asked
Ed if he could call in the emergency to air traffic control and make them aware
of the fact
that they were now
descending. Ed immediately complied and called Mayday to Honolulu control
telling them
that United
Airlines Flight 1175 were suffering from some type of severe damage
and needed to
proceed directly towards the airport whilst also descending. This was followed
by a long pause by air traffic control.
It clearly took a
while for the controller to really appreciate the gravity of what he had just
heard.
He eventually came
back with, "Say again?" Just to verify that this was actually
happening. But he then quickly found his composure
and asked the crew
for the number of souls on board as well as the fuel remaining. Those are
standard questions needed
to prepare the
emergency services for a possible worst-case scenario and is almost always
asked in a situation like this
and Ed gave him
that information but after he had done that, all three pilots just looked
at each other for a
few seconds. It had just sunk in that there were over 350 people on board this
flight,
whole families,
possibly whole villages whose lives were likely affecting many thousands more.
They just had to
get this aircraft safely down on the ground. Now, I normally advise against letting
emotions get involved
when dealing with
sudden and complicated emergencies because generally it's better to try and
fall back onto trained procedures
and decision-making
models as emotions have a way of increasing stress to levels where effective
decision-making can become very difficult
but in this case it
seems to have worked as a catalyst for the crew to maintain even higher focus.
The aircraft was
now steadily descending and Captain Behnam asked his first officer to calculate
the best speed
and altitude for a
drift-down procedure. This is something that we use when we want to maximize
our time at higher altitudes
and therefore,
extend our range as much as possible. Whilst Paul was calculating the values,
they also quickly
determined that the best airport for landing would be their destination,
Honolulu,
but it was still
around 200 nautical miles away and they had no idea how damaged their aircraft
was or how long it would stay together.
This meant that
they would need to drift it down gently to make sure they wouldn't make the
damages worse and also
to maximize their
chances of actually reaching the airport. Captain Behnam had already firewalled
the remaining left
engine when the explosion occurred and that's something that we normally only
do in extreme circumstances
like in a
terrain-escape manoeuvre. If we do that, we only keep it firewalled for a
limited amount of time to not overstress the engine
but Captain Behnam
now felt that he needed all the thrust he could possibly get in order to keep
the aircraft under control
so the engine was
just left firewalled at full thrust. First Officer Paul soon determined
that the best speed
and altitude for a drift down would be 230 knots and 23,000 feet.
By decelerating to
that speed with maximum thrust set, this would keep the aircraft descending
with minimum
possible vertical speed. But as Captain Behnam started decelerating the
aircraft
and the speed
started getting back towards 245 knots, the aircraft suddenly started shaking
even more and soon the stick shaker also activated.
They were about to
stall. Now that shouldn't have been happening at that speed but here it was
happening anyway
and all pilots are
taught that the only way to get out of an impending stall is to immediately
lower the angle of attack.
Captain Behnam
reacted instinctively and immediately lowered the nose but by doing so the
vertical speed increased
to 3,000 to 4,000
feet per minute and if that descent rate were to be continued, the aircraft
would hit the water
way before reaching Honolulu. So what was going on here?
Why was the
aircraft stalling at such a high airspeed where the drift down tables were
suggesting an even lower speed to fly?
Well, when those
tables were made, they were calculated with single-engine performance but with
the non-functioning engine still in one piece.
What this crew was
now dealing with was a severely damaged engine, missing most of its aerodynamic
fairings
that would guide
the air smoothly past the cowling and then over the wing. What this meant was
that the airflow
was now severely
interrupted over the right wing which lowered the amount of lift that that wing
could produce.
That was actually
what had caused that rapid roll to the right as the explosion occurred and was
now also causing the much higher stall speed
on that wing that
they were now experiencing. But the pilots still had no idea about this.
The Boeing 777 has
no external cameras that can be accessed from the cockpit so whilst stabilizing
the aircraft
at a slightly
higher airspeed around 245 to 255 knots, Captain Behnam
now took another
decision. He asked Ed, the jump-seating first officer, if he could go back
through the cabin and have a look
at the state of the
engine and then report back. Ed nodded and immediately started making his way
back
towards the
aircraft's midsection close to the wings and a few minutes later, he came back
with a truly terrifying video on his mobile phone.
In it, the full
scale of the damage could be clearly seen and also how the damaged fan was
still wind-milling with the whole engine oscillating
from side to side
due to the unusual aerodynamic forces that was now acting upon it.
There was no way of
telling how long this engine would actually stay connected to the airframe or
if the departing debris had damaged any other part
of the aircraft
behind it as it disintegrated. With the airspeed now under control
and the stick
shaker quiet, the descent rate had dropped to a more manageable 1,000 to 1,200
feet per minute
as the aircraft
descended through roughly 33,000 feet. At this point, they entered a thick
cloud layer which they had seen during
their pre-flight
briefing which also meant that they would now lose all outside visual
references
until they broke
out of the clouds at around 2,000 feet, hopefully, close to the airport.
But what about what
was happening behind them then? What about the cabin crew and passengers? Well
this would have been
an absolutely
terrifying experience for all of them. During the first 15 minutes of this
emergency
the pilots were
completely consumed by controlling the aircraft, securing the engine and
finding a safe new flight envelope to maintain
and this meant that
none of them had had any chance to make a PA to the passengers to reassure them
and explain to them what was going on.
All passengers who
were sitting on the right side of the aircraft close to the wings were able to
clearly see the mangled engine
rocking forth and
back outside their windows and this combined with the absolutely
extreme initial
vibrations would have likely scared even me if I was on board.
As the situation
got more and more under control, Captain Behnam asked the lead purser to come
into the flight deck
to give her a
briefing by himself and to project some calm onto the situation.
He was very
transparent and explained that they had suffered severe damage to the right
engine and possibly to even more parts of the aircraft that he couldn't see.
He also told her to
start preparing the passengers for a possible ditching at sea.
He did this because
he knew that the cabin crew procedure needed to do this could last as long as
25 minutes
which was more or
less exactly the time he calculated that they had left airborne and he also
informed her
that they would be
calling, "Brace, brace, brace," about two minutes prior to landing.
Now Captain Behnam
didn't actually think at this point that they would have to ditch but he didn't
know just how
the aircraft would
react when they started slowing it down for landing and extending flaps,
and on top of that,
he knew that there would be no harm in having the cabin prepared for the worst
case scenario.
Again, this is
excellent thinking on behalf of the captain. It's always better to be safe than
sorry and this way, the cabin crew would be busy with their drills
which would also
keep them and the passengers occupied and prepare them mentally for an
evacuation if that would be needed later on.
After this point,
all communications with both air traffic control, the cabin crew and the
passengers were delegated to Ed on the jump seat
so that the two
pilots could focus solely on getting the aircraft safely down on the ground.
The flight
attendants ended up doing an absolutely fantastic job, caring for the
passengers and preparing the cabin
for the coming
emergency landing whilst Ed kept updating them every 10 minutes or so about the
progress.
Air traffic control
also did a great job by not overburdening the pilots with questions and just
giving them the info
and clearances that
they asked for and kept all of the other traffic out of the way.
Now notice how all
members of this situation worked like one big organism, utilizing each other's
strength,
keeping each other
updated without overburdening anyone with questions and non-essential
information?
For any budding
pilots or really anyone out there, this is a behavior that's really worth
remembering.
I also want to
point out here that this scenario would have felt very different from any
training scenario that this crew
had ever
encountered in the simulator. The simulators are not equipped to simulate the
level of vibration
that they were now
experiencing and on top of this, this engine failure behaved very differently
from the way that it was normally simulated.
The changed
aerodynamics from the mangled engine also impacted the way that the aircraft
needed to be handled and several systems including the EECs, the fire loops
and all automatics
had been removed by the explosion. But even though this was so different,
the hundreds of
simulator hours that these pilots had accumulated together as well as the
thousands of hours of actual flight experience
they shared had
created something known as resilience. Resilience is where you can utilize
all of your
previous knowledge and experience to tackle completely new situations that you
might face.
Other great
examples of resilience was the Miracle of the Hudson and Qantas Flight 32 both
of which I have previously covered on this channel.
And this, by the
way, is also exactly the kind of thing that I love to discuss with my Patreons
on our monthly Zoom hangouts.
Please consider
joining you too if you want to support me and my team and take part of the work
that we do.
Anyway, First
Officer Phil now also got into contact with the airline via SATCOM and briefed
the operations officer about what was going on
so that the airline
could start getting their crisis center ready. Meanwhile, Captain Behnam kept
counting in his head.
If he could just
continue descending with around 1,000 to 1,200 feet per minute with the
distance and speed
that they now had,
they should be able to reach the airport. By getting a direct routing
towards their final
they had also saved around seven minutes of flight time which could become
crucial if it turned out that they couldn't arrest
the descent rate
down towards the end. So at this point, it was all about continuing to fly
and also start
getting the aircraft ready for the landing. More and more non-normal checklists
also started popping up
on their EICAS
which the crew needed to take into account. Since they had been flying with max
thrust set
on the still
working left engine it had consumed much more fuel than expected which also
meant that they were eating into their diversion fuel.
On top of this,
this had also caused a fuel imbalance between the left and the right main tank
since the left engine was only
using fuel from the
left hand side. All of this was being dealt with by First Officers Paul
and Ed while
Captain Behnam was completely focused on just keeping this stricken bird
flying.
The two First
Officers started cross feeding fuel from the right tank to the left engine as
they passed around 10,000 feet descending
and at this point,
Ed also fastened the shoulder harnesses on Captain Behnam's seatbelt
since he wasn't
able to do this himself due to the sheer difficulty of the handling
that he was
experiencing. After this, it was also time to start briefing the approach
so Ed took the
weather for Honolulu which still was overcast but with, thankfully, good visibility
and winds for landing.
Honolulu approach
soon handed them over to the Honolulu tower frequency and when First Officer
Paul called them up,
they were advised
that they could expect radar vectors for an ILS approach into Runway 04 Right.
But that was no
good. Both Captain Behnam and Ed on the jumpseat were familiar with the airport
and knew
that Runway 04
Right was quite short and wouldn't be long enough for the high-speed
single-engine approach
that they now had
ahead of them. Runway 08 Left was long enough but unfortunately closed
for some type of
work on that day. So Paul instead asked for vectors towards Runway 08 Right,
a long enough
runway but unfortunately, without an ILS approach.
On that runway,
there was only a non-precision GPS-based RNAV approach available, meaning that
the crew would now soon have
to fly a manual
single-engine non-precision approach in full instrument conditions accompanied
by some of the
heaviest vibrations that they had ever experienced. Quite a challenge.
But Captain Behnam
wasn't worrying too much about that yet. He was more focused on making the
runway in the first place.
He asked Paul to
tell air traffic control to give them vectors as close to land as possible
since the waves might be smaller
on the leeside of
the island and therefore more survivable in case they would have to attempt the
ditching.
Now this is
something that I think that a lot of people might not fully appreciate. You
see, landing in water with an airliner of this size
would be an
extremely challenging maneuver to successfully achieve. Landing on water in any
situation
is hard but if you
have a stretch of smooth water like Captain Sully had in The Miracle of the
Hudson, it's still reasonably doable.
Trying to do so in
the massive waves of the Pacific Ocean is a completely different ballgame
and Captain Behnam
knew this so trying to overfly calmer waters was a really smart thing to do.
Now the tower
controller initially tried to tell the pilots to level off at various altitudes
but this was turned down by the crew.
They still needed
full thrust on the left engine to maintain speed in a descent and did not want
to end up
in another approach
to stall situation by leveling off for no good reason.
Once the controller
understood this he just left them alone with free range to intercept the RNAV
approach at their own discretion.
And here again, the
crew showed evidence of remarkable teamwork. Since the captain was solely
focused on just handling
the massive shaking
bird the two first officers together started setting up and briefing for the
approach.
And all three
pilots decided that Ed, from the jump seat, would be acting as kind of a
precision approach radar
or PAR based on
what he saw on the navigation display. This meant that he would be telling Captain
Behnam
how to turn and
descend kind of like, "Turn right onto heading 075 degrees,
now continue
straight ahead, increase descent rate et cetera." He did this all to
minimize the workload and to try
to stabilize the
approach as much as possible. Now this is not taught anywhere but a great
adaptation
to a situation and
use of resources and yet another reason why it's a poor idea
to try to reduce
the number of pilots in the cockpit. As they were intercepting the approach,
they kept the
aircraft slightly high and fast on purpose to make sure that they would have
enough energy
to make the runway
even if something further would happen. Remember they were still not sure how
the aircraft
would react when
they started extending the flaps and gear or if it would be even possible
based on the
damages that they had. When first officer Paul started briefing the missed
approach procedure
Captain Behnam
softly stopped him, "Paul, there will be no missed approach.
We are using full
thrust on the left engine just to keep the speed in descent. If we get the
flaps and gear out,
we will only have
one chance to land this thing." Now if you think that he was being
over-dramatic here, he wasn't.
He had previously
sent Ed out to also check on the back of the aircraft as he felt like the
aircraft wasn't handling properly
even with the
damaged right engine in mind. When Ed came back from that second check,
he had said that
the back of the aircraft was fishtailing left to right so violently that he had
problems even focusing to see
the panicked faces
of the passengers in the back. This had led the crew to expect that there might
also be further damage
to the tail which
they couldn't see and it was very hard to say just how long this aircraft would
stay together.
They needed to land
it as soon as possible. Now they had decided to try and land with 20 degrees
of flaps using a
speed of 145 knots in the final provided they were able to decelerate that much
with the aircraft
still flying. As they descended down the extended approach, they now gently
started slowing down
which would also
meant more and more rudder needed from the captain as the rudder becomes less
and less aerodynamically efficient as the speed decreases.
They extended one
step of flaps then two and the aircraft was thankfully still behaving okay.
At time 12:34
Honolulu time, the huge 777 finally broke through the clouds and the pilots
could see the
runway straight ahead. First Officer Paul reported this to the tower and were
immediately cleared to land.
All emergency
equipment was now standing by for them. 20 seconds later, they selected the
landing gear down
and soon received
three green lights indicating that it was all down and locked.
This was a huge
relief for everyone as the aircraft was still maintaining its speed reasonably
well even with this added drag.
When they passed
500 feet, First Officer Paul called out, "Brace, brace brace," over
the PA
to make sure all
passengers and crew were ready in the brace position for the landing and immediately
after this flaps 20 was selected
now they were only
seconds away from the landing. The giant 777 finally swooped in
over the threshold
and was immediately followed by the emergency vehicles who were waiting for
them.
Captain Behnam was
now in a trance-like state and all he could focus on was getting this aircraft
down gently
not to cause any
further damage and to start breaking. He had to get this right.
At time 12:37:15,
the main landing gear touched down so smoothly that some of the people on board
didn't even notice
it. Captain Behnam immediately started to gently brake
and he later said
that this was one of the best landings that he'd done in his entire career.
The aircraft slowed
down to taxi speed and rolled gently out onto taxiway Romeo Gulf where it was
brought to a complete stop.
First Officer Paul
looked over towards Captain Behnam and said to him, "You can let go now,
Captain."
Because he saw that
his captain was still squeezing the controls and thrust levers as hard as he
had been doing during the last 40 minutes.
Now it was time to
do the next step since an emergency is not over just because the aircraft has
landed.
The crew got into
contact with the emergency services who were now assessing the aircraft from
the outside and was soon told that apart from a small hydraulic leak,
there was nothing
else requiring an immediate evacuation. The crew acknowledged this
and passed that
information on to air traffic control who gave them a clearance to continue
taxiing on their own power on to stand
and once they
reached there, the shocked passengers and crew erupted in cheers as the engine
was finally turned off
and that thought
(chuckles) actually brings some tears to my eyes when I think about it.
Anyway, everyone
then disembarked normally and were met by the emergency response team from
United Airlines at the gate.
The pilots had
exited the cockpit at that point to say goodbye to each one of the passengers.
Some were crying, some were trying
to show a brave
face but towards the end, a blonde little girl came up to the captain and told
him with a smile,
"That was so
cool, best roller coaster ride ever," before she exited together
with her presumably
less impressed mother. Life is all about perspectives.
Now as soon as they
had landed, the phones of the pilots all started lighting up with calls from
the company
but they were well
aware of the procedure they needed to follow. When something like this happened,
first of all, they should always call their union hotline
to get the
appropriate legal advice. It is really important not to say
the wrong things in
this situation so as sad as it sounds this is what we all should do.
The cockpit voice
recorder was also protected, something that would become crucial for the coming
investigation
together with the
flight data recorder and after having shut everything down correctly and made
the appropriate tech log entries
the crew left the
aircraft. Outside, the pilots followed the engineers and mechanics around to
look at the damage
and they took some
photos, some of which you can see here. Both pilots were initially grounded on
full pay,
pending
investigation which is standard protocol but they were soon back in the air again
with only the finest comments from the airline.
The investigation
showed that the catastrophic engine failure had been caused by the fatigue
crack
that I explained
about before and it shone a very harsh light on the TAI inspection procedure
where the inspectors
had been seeing but not highlighting this crack several years earlier.
This led to several
improvements on this procedure as well as an increased inspection interval of
the fan blades of these particular engines
and the additive of
a stronger engine containment structure.
Unfortunately
though, this didn't stop a very similar accident from happening at a later
point also including a United Boeing 777
which increased
this scrutiny even further. And in a very funny twist,
the passengers on
board that second aircraft was, after the incident, booked onto a new aircraft
to complete the trip and that aircraft
was the very same
aircraft that I've told you about in this story which had been returned to
service after repairs.
It really is a very
small world. Now the actions of these pilots have been used
as positive CRM
stories for training both by United and other airlines after this thing
happened
and Captain
Christopher Behnam and First Officer Paul Ayers were on the 18th of July, 2019
awarded
the Superior
Airmanship Award by the Airline Pilots Association for their skill and teamwork
in this accident.
Now there is also
another reason why I've chosen to make this video right now in my summer house
in Sweden during vacation
and that is that on
the 8th of August this year, 2024 Captain Christopher Behnam made his very last
commercial flight before retirement.
He flew together
with his family to London where his dream of becoming an airline pilot had
originally started
and on behalf of my
entire team, I would like to send our heartfelt congratulations
to Christopher for
a career well-served as well as our best wishes for his retirement.
Very few pilots are
ever put in the ultimate challenge of their skills and knowledge and you should
be proud of the way
that you and your
team handled it on this day. Captain Behnam has also written a book about this
experience
and his life and
it's a really great book. I will put a link to it in the description below
where you can also find links
to my merch and my
Patreon crew. Have an absolutely fantastic day wherever you are
and I'll see you
next time or maybe in my next Patreon hangout, bye bye!