- [Petter] Aircraft accidents
are always caused by a combination
of several factors and the thing
that gets the sequence rolling
is often something simple and mundane.
But this is the first time I've ever come
across a single letter kicking it off.
- [GPWS] Sink rate. Pull up.
- Stay tuned.
When you hear the word Tenerife
in aviation context, people almost always think
of the world's worst aviation disaster,
the collision between two Boeing 747s
at Tenerife's Los Rodeos Airport back in 1977.
But the island of Tenerife,
the largest of Spain's Canary Islands,
actually suffered a string of disasters
between the 1950s and 1980s,
who collectively claimed 950 lives
and that infamous runway collision
was just the worst one of those.
So today I will tell you the story of
the last major incident to happen there,
a story that took place on a rainy spring day back in 1980.
And this one, I think a lot fewer of you have ever heard of.
In the morning of the 25th of April 1980,
the crew of Dan-Air Flight 1008
were preparing to depart from Manchester in England
on a charter flight, bringing tourists down
towards Tenerife North Airport,
then known as Los Rodeos.
During the 1970s and '80s,
Dan-Air was one of Britain's largest operators
of inclusive tour flights, chartered by tour operators
to transport fixed groups of people
down to popular holiday destinations
in Southern Europe and North Africa.
Among the aircraft types operated
by Dan-Air was the mighty Boeing 727,
and Dan-Air were actually the first British airline
to import this model, which had then had
to undergo several unique modifications
in order to meet British safety standards.
Now it would later turn out
that the 727s were a financial disaster for Dan-Air,
but by 1980, that was not yet very obvious.
The aircraft that the crew were going to operate
on this day was 14 years old
in generally good condition
and could seat a maximum of 144 passengers.
So with a total of 138 passengers booked,
it was almost completely full.
The crew consisted of five flight attendants
and three pilots, meaning that in total,
there were going to be 146 people on board
once the flight got on the way.
The pilot in command was a very
experienced 50-year-old captain
who had around 15,300 total flight hours,
which included almost 2,000 on the Boeing 727.
He had flown this route down to Tenerife North
a full 58 times before this flight,
making him very familiar with it in general.
But as we will soon see,
being familiar with the destination doesn't mean
that it can't throw a few surprises.
His second-in-command was a 34-year-old first officer
who, on this day, had about 3,500 hours in total,
of which 618 were flown on the 727.
And the third flight crew member
was a 34-year-old flight engineer
whose experience was similar to that of the first officer.
Now all of the pilots had been off
for more than 24 hours before this duty
and the scheduled departure time
was at a very civilized hour,
so there's no reason to believe
that fatigue played any role
in what was soon about to happen.
Now instead the crew were likely in a quite good mood
as they completed their normal pre-flight activities,
checking weather, NOTAMs and flight plans,
which all looked okay.
It looked like it was going to be a very pleasant flight
down towards the Canary Islands.
So after having boarded everyone
and completed the pre-flight set up,
the crew started up their engines
and taxied out for takeoff from Manchester at time 9.22 am,
with the captain as pilot flying
and the first officer as pilot monitoring.
Now the climbout and cruise phases
of this flight went off without a hitch,
but the pilots then likely started preparing
and briefing for the approach
a bit earlier than usual on this day.
And that was because they had seen,
during their pre-flight briefing
that the approach they had ahead of them
was possibly going to be a little bit unusual.
You see, in the Canary Islands
the prevailing winds normally blew
from the Atlantic Ocean in the west,
causing most flights to approach
from the east using Runway 30
in order to land with a headwind.
But on this afternoon, the wind was instead blowing
from the other direction, from the east,
forcing inbound aircraft to approach
the reciprocal Runway 12 instead.
Now we don't know how many times the captain
or the other crew members
had actually used Runway 12 in the past,
but it was likely not something that they did very often.
And to make things even worse, Tenerife North Airport was,
and still is, notorious for its frequent,
fast-building fog that can appear from nowhere within minutes.
The airport sits at 2,000 feet above sea level
on a shoulder between two mountains,
and the marine fog that forms over the ocean
frequently collides with the western slopes of Tenerife
and then gets funneled
through the gap directly over the airfield.
But like I mentioned before,
on this day the reported weather at the airport
was more or less okay, with around six kilometers of visibility
and scattered clouds at 400 feet,
broken at 800 feet, and further scattered clouds
at 1,100 feet with some light drizzle,
not great for sunbathing,
but good enough for normal landings.
But these cloud layers also meant
that higher up on the mountainsides,
the fog was extremely thick,
so thick in fact that a weather station located
at a close to 8,000 feet elevation
on the mountainside reported nil visibility.
This meant that the very high terrain south of the airport
would be completely obscured,
including the nearly 12,200-foot Teide Volcano,
which is the defining geographical feature on Tenerife.
Because of that, the minimum safe altitude
in the airspace south of Tenerife North Airport
was 14,500 feet, which is worth remembering.
Anyway, as the flight near the Canary Islands,
the first officer made contact
with the Las Palmas Area Control Center,
who soon cleared them to descend down to 11,000 feet.
The first officer read this back
and the crew initiated the descent,
and after they reached that altitude,
they contacted the Tenerife North approach controller
and reported that they were now 14 nautical miles
away from the Tango Foxrot November VOR beacon,
and that they were ready
to receive their approach instructions.
Before we continue here,
it's probably worth explaining a bit more about
the different approach aids
that the crew were now going to use
as well as their procedures.
A VOR beacon, where VOR stands for:
Very High Frequency Omnidirectional Range,
is a type of radio navigation beacon
that was very widely used in the days before GPS
and is actually still quite common,
especially here in Europe.
These VORs emit signals hat are modulated differently
depending on the direction of the emission,
which allow the VOR receivers on board aircraft
to determine the precise magnetic bearing
from the VOR to the aircraft.
This enables the pilots to navigate using imaginary lines
or radios defined by a particular bearing
from the beacon.
So, for example, the 270 degree radial
from the VOR points due west and so on.
A lot of airports have VORs installed
to help pilots locate the airport before starting to maneuver
for the approach, and it can also be used
to align the aircraft with the runway as an approach aid
if an instrument landing system, ILS, is not available.
But in this case, the Tango Foxrot November VOR
was not actually located at the airport.
Instead it was sitting on a hilltop,
a few miles northeast of the airport
in order to maximize its detectable range.
Located at the northeast end of Runway 12-30,
there was a less-sophisticated beacon called an NDB locator
with the Morse code identifier Foxrot Papa.
A non-directional beacon, or NDB,
is a radio aid that can be tracked
using an automatic direction finder, an ADF,
and this is a very simple instrument which just points
in the direction that a signal is coming from,
but it doesn't contain any radial information,
which makes the NDB navigation less
precise than navigating using a VOR.
In this case, because the Foxrot Papa beacon was used
to mark the entry point to the approach procedure
for Runway 12, it was also known as a locator
rather than just an NDB.
And in order to approach Runway 12,
a flight inbound from the northeast like this flight was
would normally need to fly first
via the Tango Foxrot November VOR
and then turn southwest onto Radial 255
directly towards the Foxrot Papa NDB.
After reaching the Foxrot Papa,
the aircraft should then turn right onto an outbound heading
of 302 degrees, which would take it out over the ocean,
before making a teardrop course reversal
to the left back towards the airport.
And from that point, the aircraft would be in a position
to pick up the instrument landing system,
which would then guide
the aircraft the rest of the way down to the runway.
Now this was quite a bit more complicated
than the more commonly used Runway 30 approach,
which just involved flying to an NDB called Tango X-ray,
from where the instrument landing system
could then be picked up immediately.
Now the reason that these procedures
had to be flown this way
was that there was no radar available at Los Rodeos Airport,
so all approaches had to be intercepted
using procedural arrivals.
But then again, flying procedural approaches
would not have been very uncommon back then,
and there was nothing in this procedure
that was particularly out of the ordinary,
except maybe that high terrain to the southwest,
which I mentioned before.
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that are out of the ordinary,
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Yes.
After establishing contact at time 13:16,
the Tenerife North Controller cleared the flight
to descend down to 6,000 feet
in preparation to cross Tango Foxtrot November
and then to enter the approach procedure.
The captain dialed in the new cleared altitude,
the flight engineer reduced thrust in order to descend,
and the first officer then reported
when the aircraft was seven nautical miles away
from the Tango Fox November beacon
in order to get further instructions.
At that same time, he also requested the local air pressure,
QNH, in order to get the correct reference
to the altitude above the sea,
and also the QFE, which would give him
the altitude reference over the airfield.
Once those values had been received and set,
they were then cross-checked
in accordance with their standard operating procedures,
and the captain now also suggested
that the first officer should tune
the ILS frequency on his navigational radio box,
and he also confirmed that the outbound heading
after Foxtrot Papa would be 302 degrees.
So at this stage, everything was completely normal
and the crew seemed to have a good grasp
of the procedure they had in front of them.
But just a few miles ahead,
an island-hopping turboprop belonging
to Spain's flag carrier, Iberia, was also an approach
to Runway 12, and the crew on board that aircraft
were communicating with the controller in Spanish.
Now the pilots of Flight 1008 didn't understand Spanish,
and from their conversations,
it doesn't seem like they paid much attention
to that aircraft at all.
Instead, they continued to monitor their position,
relative to the Tango Fox November VOR,
and at time 13:18:15,
the captain called out, "Just about to go overhead."
The first officer then reminded
the captain that the procedure called
for them to leave Tango Fox November on Radial 255.
But as it turns out,
the aircraft actually passed a little less than a mile east
of the VOR, and after passing abeam it,
they were also slow to make the right turn,
which meant that they never
actually intercepted that 255 radial.
Now, we can never know for sure why this happened,
but it was most likely done on purpose.
You see, the distance
between Tango Fox November and Foxtrot Papa was very short,
and Flight 1008 was traveling
at an airspeed of around 250 knots
when they passed abeam to the VOR.
Today, we wouldn't fly that fast
when starting a tight procedure like this,
since our aircrafts are now very slippery
and take time to decelerate.
But older aircraft like the 727
had much less effective wings,
which meant that they could easily keep the speeds up high
for longer, since the speed would just rapidly bleed off
when the thrust levers were closed.
This also meant that most jets
approaching Tenerife back then, including this one,
would normally overshoot this first turn slightly
before correcting course in order to be able
to intercept the 302 outbound course
from the NDB at a slightly more comfortable angle.
There was so little time between Tango Fox November
and Foxtrot Papa that they probably wouldn't be able
to intercept the radial anyway.
And on top of that, if they flew directly over Foxtrot Papa,
they would potentially overshoot the pattern significantly,
which could take the aircraft
into the area south of the airport
where the minimum safe altitude was 14,500 feet.
Now, this is obviously not how this was supposed to be done.
A lower speed would have solved all of those issues,
but sometimes, procedural shortcuts like this can start
to creep in due to pure convenience and time saving.
And if I was to guess, this was likely
the reason that the captain of this flight flew a bit wide
around the Tango Fox November.
Now, due to some radio chatter
with the Hapag-Lloyd flight
that was taking off from Los Rodeos
plus some other distractions,
the flight crew didn't actually report
crossing Tango Fox November
until 33 seconds after they had passed abeam hit.
And like I mentioned,
Tenerife North Airport didn't have radar at the time,
so position reports like this
were the only way for the controller
to determine where the traffic was located.
As a result, when the crew reported
that they had just passed Tango Fox November,
the controller realized that the 727 was traveling so fast
that it would risk getting too close
to the slower Iberia turboprop in front of them
if he didn't do something.
So he hastily decided to put Flight 1008
into a holding pattern
in order to ensure sufficient traffic separation.
At time 13:18:54,
the approach controller transmitted the following message,
"Roger, the standard holding overhead Foxtrot Papa
is inbound heading 150,
turn to the left, call you back shortly."
And this would end up being the critical moment
that put the accident sequence into motion.
So let's take a moment to analyze why.
Despite the controller's statement
that this was a standard holding,
there was actually no officially published holding pattern
around the Foxtrot Papa beacon.
There was a published holding
around Tango Fox November,
as well as around Tango X-ray,
forming part of the go-around procedure for Runway 12,
but Flight 1008 was not in a position to enter any of those.
Instead, the controller essentially
invented a holding pattern based on Foxtrot Papa,
and he did so so quickly
that this was likely not the first time
that he had used this particular pattern.
Now, it's not wrong or illegal to make up holding patterns.
In fact, that happens all the time, and it's perfectly okay
as long as it doesn't cause any issues
with terrain or traffic separation.
But the issue here was that the controller said
that this was a standard holding,
which would imply that the holding could be found
in the published approach chart,
and therefore needed to be verified by the pilots.
On top of that, the entry
into this suddenly-proposed holding pattern
would not be very simple
from the position that the aircraft was now coming from.
What the controller wanted the aircraft to do
was to join a left-hand holding pattern over Foxtrot Papa
with an inbound course of 150 degrees
and an outbound course of 330 degrees.
If it was flown that way,
it would keep the airplane over relatively low terrain.
But to do this, Flight 1008
would have to first fly over the beacon,
then turn right onto heading of 330,
fly outbound for one minute, perform a course reversal,
and then proceed inbound
to Foxtrot Papa again on the requested inbound course.
Quite a complex maneuver to fly
when you're almost over the beacon.
Now, the pilots might have eventually figured this out
if not for a tiny slip of the tongue by the controller,
which changed this entire course of events.
Remember that the controller wanted Flight 1008
to fly counter-clockwise
around the holding pattern, making left turns?
Well, this meant that what he wanted to say
was turns to the left,
but what he actually ended up saying
was, "Turn to the left," which has a very different meaning.
Turn to the left is normally interpreted
as a command to turn left, right away,
which was not at all what the controller
wanted them to do here.
What he attempted to say
was only a description of the holding pattern,
which is technically just informational,
not an order, and that also made sense,
given that he didn't have any radar available.
Spanish investigators later used this
to argue that the controller didn't bear any responsibility
for issuing a non-standard clearance,
but given how his call actually sounded
to the pilots, that's not completely fair.
Anyway, when the flight crew received this message
from the controller, they simply replied,
"Roger," with no further readback
or request for confirmation.
They might have thought at first
that they understood what he said,
but within 10 seconds, the captain realized
that he wasn't able to picture
what the controller was asking from him,
so he said, that's an odd sort of one, the runway.
He then interrupted himself
with a confirmation that they had 1,000 feet
to go to their cleared altitude of 6,000 feet,
and after that, the first officer said,
"No, I'm not, er... Supposedit's all right?"
The captain continued with, "I'll just turn straight round
to the left on the 150 when I go overhead then,"
to which the first officer seemed to agree.
Now this shows that the captain clearly believed
that he had been told to turn left on to heading 150
after crossing Foxtrot Papa,
which again was not at all what the controller had intended.
A command to turn to the left
was completely incompatible with an instruction
to fly a holding pattern inbound on 150 degrees
to Foxtrot Papa since, like what I said earlier,
that would require a right turn followed by a course reversal.
So in the captain's mind,
the instructions didn't make sense,
but he had been able to pick out two elements
in the message which seemed clear to him,
150 and turn to the left.
So with Foxtrot Papa now coming up
in less than one minute,
he didn't have a lot of time to figure it out.
In a stressful situation,
without fully comprehending what the controller had said,
he accepted that the best thing to do
was just to execute the part of the clearance
that he understood,
and then try to figure out the rest later.
In hindsight, it's easy to say
that he shouldn't have acted
on an incomplete understanding of those instructions,
but in that moment, with the sudden time pressure
and the added workload of the sudden holding clearance,
it would have been a lot harder
to think with that kind of clarity.
And it is also worth remembering
that this all happened in a 727 cockpit,
with no fancy navigation displays, only dials.
Besides, this CVR transcript suggests
that both the first officer and the flight engineer
were looking at the charts when this all happened,
likely searching for that standard holding
in order to be able to verify it.
And the first officer had said, "I suppose it's all right,"
which might have reinforced the captain's belief
that he had understood the clearance correctly.
Anyway, seconds later, having made his decision
on how to fly, the captain focused
his attention on the rapid approach
of the Foxtrot Papa NDB.
He said, "The only thing is, we're just about to miss it.
(chuckles) It's too close."
At this point, the captain and the first officer also agreed
to tune both automatic direction finders
to the frequency of the Foxtrot Papa,
so that they could track it more easily
during the holding pattern.
And finally, at time 13:19:46,
they passed abeam Foxtrot Papa,
slightly to the southeast, and the captain called it out.
This prompted the first officer to report
the waypoint passage to the controller,
and he also confirmed that they were now taking up the hold.
But in reality, they actually kept flying straight ahead
for another about 20 seconds,
covering around two nautical miles
before beginning the left turn.
Now, the reason for this delay isn't really known,
but it might have been because the pilots
were still trying to wrap their heads
around the maneuver that they now had ahead of them.
In fact, a few seconds before they began that left turn,
the first officer said, "Bloody strange hold, isn't it?"
Which indicates that he was still mentally focused
on the confusing instructions.
In response to that, the captain said,
"Yeah, it doesn't...
Isn't parallel with the runway or anything."
Now, I just want to stop here and drive home
what is probably one of
the most important points of this whole video.
If something seems strange with a clearance and you get
that pit in the stomach feeling
that something just isn't right,
always speak up and ask for further clarification.
This goes for all walks of life and all industries,
but especially if you're flying an aircraft.
It's always better to ask one time too many
than one time too few,
and I want every one of you out there to remember that.
This, by the way, is also exactly the kind of discussions
that I'm having regularly on my Zoom hangouts
with my Patreon crew,
and I hope to see you there as well next time.
Just go to patreon.com/join/mentourpilot
if you think that sounds interesting.
Anyway, at this point, what the flight crew didn't yet know
was that by overshooting Foxtrot Papa
and then turning left onto a heading a 150 degrees,
they were now on a track to overfly the northern shoulder
of La Esperanza, a sub-peak
along the island's central volcanic ridge
that stretched north from El Teide.
The terrain directly beneath their projected flight path
actually didn't exceed 5,000 feet,
but it did lie within the sector,
where the minimum safe altitude was 14,500 feet.
So strictly speaking,
since they weren't flying a published procedure,
maneuvering at only 6,000 feet
would have been prohibited in this area.
The final report would later place some blame
on the flight crew for flying into this area
without being aware of the applicable MSA,
but it seems likely that at this point,
they were still thinking that they
were flying an official procedure,
even though they couldn't find it on their charts.
At the same time as Flight 1008 completed
their left turn onto a heading of 150
and started flying towards the southeast,
the approach controller called up
the Iberia Airlines flight ahead of them
and asked them to verify when they had left 5,000 feet.
Only seconds later, the pilot of that aircraft replied
that 5,000 feet was now free
and that they were in the middle
of a procedure turn to intercept the ILS.
As these calls in Spanish were happening,
the first officer on Flight Engineer
on board Flight 1008 continued to compare ATC's instructions
with what was printed on their chart,
saying things like, "It's that way, isn't it?"
"That's a tree, isn't it?"
And, "Yes, well, the hold is going to be here, isn't it?"
It's likely that they were now very skeptical
about the maneuver that they were flying,
but we can never be 100% sure
since that wasn't formally verbalized.
Anyway, as these discussions were taking place,
the controller now called them up
and cleared them to descend down to 5,000 feet
since the Iberia flight had now left that altitude.
And in response, the flight engineer again reduced
the thrust and the captain initiated the descent.
But as they were doing this, the captain suddenly said,
"Hey, did he say it was 1-5-0 inbound?"
likely realizing that his mental picture
of where the controller was sending
them didn't actually make any sense.
The first officer had probably suspected
that from the very start because he now replied,
"Inbound, yeah."
And in response to that, the captain said,
"That's... I don't like that."
The first officer continued by saying,
"They want to keep going more around, don't they?"
It's not completely clear what he meant by that,
but it is possible that the first officer believed
that they were supposed to keep turning left,
making a three quarters turn onto
the outbound leg of the holding pattern,
after which they would come back
to Foxtrot Papa on the inbound heading of 150.
If that was the case, it would mean that
even the first officer had indeed interpreted
the call from the controller as an instruction to turn left.
And that would also explain why he
hadn't spoken up when the turn started.
When I read this part of the report,
I could really feel that cold feeling in my stomach.
You know, that feeling that you get
when you realize that something is really wrong,
but you still can't figure out what or how.
But we don't know if the pilots
had yet realized just how dangerous
their current flight path was.
But the captain's statement of,
"I don't like that," definitely showed some real concern.
Again, make sure you always know what clearance
you have been given, and if in doubt, ask.
Anyway, before the pilots could spend much more time trying
to work out what was wrong,
the ground proximity warning system
suddenly activated at time 13:20:50.
The Boeing 727 was equipped
with a first generation GPWS,
which was state of the art at the time,
but also much less capable
than the enhanced ground proximity warning systems
that we have on board today's aircraft.
Modern EGPWSs compares the position
and projected path of the airplane
to a digital terrain database.
But the original GPSs could only look
at the terrain directly beneath the aircraft
using its radio altimeter.
If the closure rate with the terrain was too high,
it would an issue sink rate or pull up warnings.
But if the terrain ahead of the aircraft was rising steeply,
the system wouldn't know that,
so these warnings could still come too late.
In this case, the airplane
was now passing over the northern shoulder
of the central volcanic ridge while in descent,
and that resulted in a rate of terrain closure
greater than 6,000 feet per minute,
triggering the warning envelope.
But the maximum height of the ridge ahead of them
was actually less than their current altitude.
So in their present trajectory,
they were not in any danger of striking the terrain.
But, of course, the pilots who had now lost
their position situational awareness
and were still flying inside of the clouds
had no way of knowing this.
So in response to the GPWS warning,
the captain immediately announced,
"Okay, overshoot," which is an old British term for go around.
As the flight engineer advanced
the thrust levers to the takeoff go around thrust,
the captain also halted their left turn
and added, "He's taking us around to the high ground,"
and after stating that, he continued rolling right
onto a steeper and steeper right-hand turn.
But what he didn't do was
to raise the nose in order to initiate the climb.
And why was that then?
Well, during GPWS response training,
we pilots today are required
to practice a terrain escape maneuver in the simulator,
which includes disconnecting the automatic setting,
full thrust pitching up to 20 degrees,
making sure the speed brake lever is down,
making proper call outs and so on.
This maneuver is drilled into everyone flying today
in order to make sure that the response
to a hard GPWS warning
is immediately executed from memory and without questions.
As it turns out, the captain and the flight engineer
had also undergone some type
of GPWS training back in 1978,
and Dan-Air did have a procedure for GPWS response,
but back in those days GPWS was a very new technology
and there is a possibility
that training had been only theoretical.
So we don't know exactly what was going
through the captain's head, but based on his statement
that, "He's taking us around to the high ground,"
he probably believed that the controller's instruction
to turn left was faulty
and that the controller had told him
to turn towards an unsafe direction.
Believing that the GPWS warning occurred
because they were turning left towards high terrain,
the captain may have reasoned
that the best way to escape the situation
was to turn to the right instead.
So without having practiced the maneuver
in the simulator, the captain's immediate reaction
was to turn rather than to climb,
which sadly would seal their fate.
Because as the right turn now continued,
the aircraft passed over
the top of the ridge and then over a valley,
causing the radio altitude to increase,
which silenced the GPWS warning,
10 seconds after it had started.
The captain commented, "Watch my eepers,"
referring to the engine pressure ratio or EPR,
essentially ensuring that the flight engineer
maintained TO/GA thrust and didn't over-boost the engines.
But it also now seems like
the first officer wasn't convinced
that they were now taking the right course of action.
So he called out,
"I suggest a heading of 1-2-2 actually
and take us through the overshoot."
A heading of 1-2-2 degrees was the heading prescribed
by the official Runway 12 missed approach procedure,
which would take them east over the ocean,
so this was a pretty sensible suggestion.
But 1-2-2 degrees was also
to the left of their current heading,
which contradicted the captain's assumption
that their left turn was what had caused the GPWS warning.
As a result, he just continued turning right past due south
and then all the way around to the southwest,
directly towards the 5,700 foot high summit of La Esperanza.
Tragically, they might still have cleared the summit
if they had just maintained altitude
or climbed following the terrain escape maneuver.
But due to the high bank angle they were now using,
the plane actually lost lift during the maneuver,
causing a slight descent instead.
Still flying over the valley, the flight engineer expressed
his nervousness by commenting, "Let's get out of here."
But the captain simply repeated,
"He's taking us around to the high ground."
Moments later, without any new GPWS warnings,
and believing that he had corrected the situation,
the captain called up air traffic control
and reported, "Dan-Air 1008,
we've had a ground proximity warning."
This was then followed
by the flight engineer calling out twice that their bank angle
was now above the recommended maximum of 30 degrees.
And his words were the last ones captured
on the cockpit voice recorder.
With the mountains shrouded in clouds, the pilots never saw
the danger coming towards them,
and the GPWS never had time
to react to the closure rate of the steep mountain ahead.
So at time 13:21:18 Dan-Air Flight 1008 crashed
into the forested mountainside of La Esperanza
at a speed of 260 knots,
just 38 meters below the top of the ridge.
Most of the aircraft disintegrated immediately,
killing everyone on board,
and a large portion of the aft cabin
was then thrown another 250 meters forward
over the top of the ridge and then down to the other side.
Down at the airport, the controller now tried repeatedly
to contact the aircraft in order to follow up
on their reported GPWS warning,
but when he didn't get any reply,
he soon activated the accident alarm.
The problem was though that
with no radar available at Tenerife North,
rescuers had no idea where the aircraft was located,
especially since it had taken a turn
that the controller had not intended them to take.
This meant that the wreckage wasn't discovered
until seven hours after the crash,
when a couple of motorists on the road
to El Teide National Park saw some debris on the road
and correlated that to the radio report
of a missing aircraft.
This crash was, and actually still is, the worst loss of life
on board a British airliner ever,
so the investigation received considerable public attention
especially when the Spanish
and British investigators didn't agree
on how to weigh the causes of the accident.
The Spanish investigators wrote
that the pilots were ultimately responsible
for being aware of their position in a non-radar environment,
and that it was their obligation
to climb to a safe altitude
as soon as they became unsure of where they actually were.
They also cited the pilot's failure to request clarification
when they didn't understand
the controller's initial transmission
as a major cause of the accident,
as well as their incorrect response to the GPWS warning.
They pointed out that if the pilots had done nothing at all
when the GPWS activated,
they would have passed safely over the ridge
and continued out over the sea.
So the Spanish investigators argued
that it was the captain's decision to turn right
that took them back around to the high terrain
and ultimately led to the crash.
But the British investigation team believed
that the controller's use of an unpublished holding pattern,
one that didn't appear on the pilot's chart,
as well as its verbal slip-up saying turn instead of turns,
played a very important role
in the pilots' loss of situational awareness.
They also noted that if the holding pattern
had been designed according to international standards,
the minimum altitude in the hold would have been 6,000 feet,
which would have incidentally prevented the crash.
But regardless of who made the most serious errors here,
the disaster was made possible
by the poor infrastructure at Tenerife North Airport,
including the lack of radar
and the poorly-designed approach procedures.
It's also important to remember
that the technology available in 1980
was far less capable than what we now have available,
and it's exactly because of accidents like this
that we today have these vastly improved systems
and that we pilots are so well trained in using them.
This accident led to recommendations
to always question any clearances that weren't 100% clear
as well as some other recommendations as well.
But in the long run, this accident also led
to better training around GPWS maneuvers
and therefore, a significant increase in safety.
Our current fantastic safety record proves
that accidents like these today are largely preventable,
but they are only preventable
because of stories like this
and that's why I keep telling them.
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