Pilatus PC-12 Autopilot Disconnect Pilot Issues

Summary

The video script discusses the recurring issue of autopilot disconnection in PC12 aircraft leading to loss of control during Instrument Meteorological Conditions (IMC). It reviews autopilot limitations, the NTSB report on a 2017 accident, and the importance of training for pilots to manage aircraft manually. The script also emphasizes the need for pilots to understand and quickly respond to autopilot disconnection, especially in turbulence, to prevent accidents.

Takeaways

• ✈️ The PC12 aircraft has a history of accidents related to autopilot disconnection and subsequent loss of control in Instrument Meteorological Conditions (IMC).
• 🔄 Autopilot disconnection on the PC12 can occur due to various limitations, including exceeding roll rates, pitch rates, or G-force limits, as well as brief stalls.
• 🚨 The autopilot system on the PC12 will disengage if it detects a stall, even a temporary one caused by turbulence, leading to a series of cockpit warnings.
• 🛠️ Pilots need to be familiar with the autopilot controls and limitations to manage the aircraft effectively, especially during single-pilot operations in IMC.
• 📚 A review of the autopilot's limitations and proper training is crucial for pilots to handle situations where the autopilot disengages.
• 👤 The 2017 NTSB report highlighted the pilot's loss of control due to spatial disorientation after an autopilot disconnection in moderate turbulence.
• 🔑 The PC12 features a big red autopilot disconnect button and a trim switch for managing the autopilot system during flight.
• 📈 The autopilot's pitch and roll rate limits are critical for pilots to understand to avoid disconnection during turbulence or aggressive maneuvers.
• 🛑 In the event of an autopilot disconnection, pilots must silence the cockpit warnings by pressing the autopilot disconnect button to focus on flying the aircraft.
• 🔄 Pilots transitioning to the PC12 should undergo professional training and maintain proficiency through annual training programs.
• 👷 For new or low-time pilots, flying with an experienced mentor in the PC12 is recommended to gain familiarity with the aircraft's automation and systems.

Q & A

What is the primary concern discussed in the video script regarding the PC12 aircraft?

The primary concern is the autopilot disconnection issue on the PC12 aircraft, which has led to several accidents, especially in Instrument Meteorological Conditions (IMC), causing pilots to lose control of the aircraft.

How many PC12 accidents were mentioned in the 2019 Used Aircraft Guide due to loss of control in IMC conditions?

There were six different PC12 accidents mentioned in the 2019 Used Aircraft Guide that were the result of loss of control of the aircraft in IMC conditions.

What is the significance of the autopilot disconnection in the PC12 aircraft?

The autopilot disconnection in the PC12 can be particularly challenging for single pilot operations in IMC conditions, as it may leave the pilot with a daunting task of hand flying the aircraft, especially if they are not comfortable or qualified to do so.

What are some of the limitations of the PC12 autopilot as discussed in the NTSB report from a 2017 accident?

The limitations include the autopilot disconnecting during spatial disorientation, moderate turbulence, and night IMC conditions, which can lead to the pilot losing control of the aircraft.

How does the autopilot engage and disengage on the PC12 aircraft?

The autopilot on the PC12 is engaged by pushing the autopilot button on the flight guidance control panel, and it can be disengaged by pressing the same button or the big red autopilot disconnect button located on the left side of the yoke.

What is the purpose of the trim trigger on the control wheel of the PC12?

The trim trigger on the control wheel allows the pilot to temporarily disconnect the autopilot and manually retrim the aircraft without completely disconnecting the autopilot, which is useful for adjusting the aircraft's trim during flight.

What are the autopilot monitor limits that can cause the autopilot to disconnect on the PC12?

The autopilot will disconnect if the roll rate is greater than 10° per second, pitch rates are more than 5 degrees per second, or if accelerations exceed a plus 1.6g or fall below a negative 0.3g envelope.

How does the PC12 handle stall conditions in relation to the autopilot?

If the aircraft enters a stall condition, even if temporarily due to turbulence, the autopilot will disconnect. This can happen if the angle of attack exceeds the critical angle as indicated by two independent angle of attack sensors located on each wing.

What actions should a pilot take immediately after an autopilot disconnect in the PC12?

The pilot should first focus on flying the aircraft and disregard the warnings momentarily, then turn off the autopilot warnings by pressing the red autopilot disconnect button on the yoke, and once the aircraft is under control, attempt to re-engage the autopilot within its operational limits.

Why is ongoing professional training important for pilots transitioning to the PC12?

Ongoing professional training is crucial to maintain proficiency in handling the complex automation and systems of the PC12, especially for pilots who are new to the aircraft or transitioning from smaller aircraft.

What is the recommendation for new PC12 pilots regarding training and mentorship?

New PC12 pilots are recommended to attend formal training programs like those offered by Simcom or Flight Safety and, if they are relatively low-time pilots, to fly with a mentor pilot for 150 to 200 hours to gain experience in various conditions.

Outlines

00:00

🛩️ Autopilot Disconnection Issues in PC12 Aircraft

The script discusses the recent loss of the Nand's Gospel family in a PC12 accident, which occurred due to autopilot disconnection during convective turbulence. It highlights a concerning trend in the PC12 community where autopilot disconnection has led to loss of control in Instrument Meteorological Conditions (IMC). The script reviews autopilot limitations, emphasizing the challenges faced by single-pilot operations in IMC, especially if not proficient in hand-flying. It references an NTSB report from a 2017 accident, underscoring the autopilot's limitations and the critical need for pilots to understand and manage these systems effectively. The autopilot's operation, including how to engage and disengage it, is explained, along with the consequences of exceeding certain flight parameters that lead to disconnection, such as roll rate, pitch rate, and G-force limits. The script stresses the importance of pilot training to handle such situations and the potential for sudden autopilot disconnection during turbulence.

05:00

🚨 The Consequences of Autopilot Disconnection in Turbulence

This paragraph delves into the specific circumstances under which the PC12's autopilot can disconnect, particularly during turbulence, and the subsequent challenges for pilots. It explains how exceeding the aircraft's angle of attack can lead to a stall, causing the autopilot to disengage. The script describes the cockpit warnings that occur when the autopilot disconnects, including visual and auditory alerts, and the importance of promptly addressing these warnings to maintain control of the aircraft. The narrative underscores the necessity for pilots to be trained to manage the aircraft manually in the event of autopilot disconnection, especially in turbulent conditions. It also touches on the importance of ongoing professional training for pilots transitioning to complex aircraft like the PC12 and the need for mentorship for less experienced pilots.

10:02

📚 The Importance of Pilot Training and Mentorship

The final paragraph emphasizes the critical role of formal training and mentorship for pilots flying the PC12, especially for those with lower flight hours. It mentions the requirement set by Clemens Aviation Insurance for PC12 owners to undergo formal training at recognized institutions like Simcom or Flight Safety. The script also suggests that inexperienced pilots should fly with a mentor for a significant number of hours to gain familiarity with the aircraft's advanced systems and automation. The paragraph concludes with a call to action for pilots to invest in their training and proficiency, ensuring they can safely handle complex aircraft like the PC12, and a note of thanks to the channel's supporters.

Keywords

💡PC12

The PC12 is a single-engine turboprop aircraft manufactured by Pilatus Aircraft. In the context of the video, it is central to the discussion as it is the aircraft model involved in several accidents mentioned. The script discusses autopilot limitations and incidents of loss of control in IMC (Instrument Meteorological Conditions), emphasizing the importance of understanding the aircraft's systems and handling.

💡Autopilot

An autopilot is a system used to control the trajectory of an aircraft without constant 'hands-on' control by a human operator. The script highlights autopilot disconnections as a recurring issue in PC12 accidents, particularly during turbulent conditions. It underscores the need for pilots to be proficient in manual control, especially when the autopilot disengages.

💡Loss of Control

Loss of control refers to a situation where the pilot is unable to maintain the desired flight path or attitude of the aircraft. The video script discusses several PC12 accidents that were the result of loss of control in IMC conditions, often following autopilot disconnection, indicating the severity of this issue in single-pilot operations.

💡IMC (Instrument Meteorological Conditions)

IMC refers to weather conditions where flight is conducted solely by reference to the aircraft's instruments. The script notes that many PC12 accidents occurred in IMC, emphasizing the challenge pilots face when they must rely on instruments for navigation and control, especially when the autopilot disengages.

💡Spatial Disorientation

Spatial disorientation is a condition where a pilot loses the ability to correctly perceive the aircraft's attitude, direction, or position relative to the ground. The video mentions a NTSB report where spatial disorientation led to a PC12 accident, highlighting the risk when pilots become reliant on autopilot in complex flight conditions.

💡Autopilot Disconnect

Autopilot disconnect refers to the event when the autopilot system disengages from controlling the aircraft. The script details how autopilot disconnections can lead to loss of control, especially in turbulence or when exceeding certain flight parameters, and the importance of pilots being prepared to manually control the aircraft in such situations.

💡Angle of Attack

Angle of attack is the angle between the oncoming airflow and a reference line on the wing or aircraft. The script mentions that the PC12 has two angle of attack sensors, and if both indicate an excessive angle, the aircraft is considered stalled. This is crucial for understanding how the autopilot can disconnect during a stall, even a brief one.

💡Stall

A stall occurs when the aircraft's wings are no longer producing enough lift to maintain flight, often due to exceeding the critical angle of attack. The video script discusses how a brief stall, even one not severe enough to trigger other stall warning systems, can cause the autopilot to disconnect, leading to potential loss of control.

💡Training and Proficiency

Training and proficiency refer to the ongoing education and skill development necessary for pilots to safely operate aircraft. The script emphasizes the importance of formal training and experience, suggesting that pilots of complex aircraft like the PC12 should undergo regular training and possibly fly with a mentor to maintain proficiency.

💡Aviate, Navigate, Communicate

This aviation mantra emphasizes the priority of actions a pilot should take in response to an emergency: first, fly the aircraft (aviate), then navigate to a safe location, and finally communicate the situation. The script uses this concept to advise pilots to focus on controlling the aircraft when the autopilot disconnects, before addressing the alarms and warnings.

Highlights

Recent loss of the Nand's Gospel family in a PC12 accident due to autopilot disconnection in turbulence.

History of PC12 accidents in 2019 showed six incidents of loss of control in IMC conditions after autopilot disconnection.

Review of autopilot limitations on PC12, especially in single pilot operations.

Autopilot disconnection can occur due to various reasons including exceeding certain flight parameters.

NTSB report from a 2017 PC12 accident highlighting autopilot limitations.

Probable cause of the 2017 accident was loss of airplane control due to spatial disorientation after autopilot disconnection.

Description of how to control and manage the autopilot on a PC12.

Autopilot disconnects if aircraft exceeds certain roll, pitch rates, or G-force limits.

Autopilot will also disconnect if a stall is detected, even briefly.

Procedures for climbing in a PC12 with autopilot, including setting altitude and speed.

Risks of autopilot disconnection in turbulence and the importance of being prepared to manually control the aircraft.

Cockpit warnings and alarms that occur when the autopilot disconnects.

The necessity to fly the aircraft first and then address the autopilot warnings.

Re-engaging the autopilot after addressing the initial disconnection and controlling the aircraft.

Importance of professional training for pilots transitioning to complex aircraft like the PC12.

Recommendation for low-time pilots to fly with a mentor before managing the PC12's automation.

Suggestion to have a second pilot or professional to fly complex aircraft like the PC12.

Acknowledgment of Patreon supporters for enabling the creation of such content.

Transcripts

the recent loss of the nand's Gospel

family ban in a pc12 accident following

a autopilot disconnect while entering an

area of convective turbulence follows a

trend in the PC2 community that deserves

a second look let's check it out if we

take a brief look back at the history of

the pc12 this article comes from the

used aircraft guide published in 2019

back in 2019 there were already six

different pc12 accidents that were were

the result of loss of control of the

aircraft in IMC conditions most of these

cases were preceded by the autopilot

disconnecting and then the pilot losing

control of the aircraft in instrument

meteorological conditions so I think

it's important to review the limitations

of the autopilot on board the pc12 very

similar to many other aircraft because

when the autopilot disc connects and if

you're a single pilot operation

in IMC conditions you could be faced

with a very daunting

task especially if you are not

particularly comfortable current or

qualified to hand fly the aircraft in

instrument meteorological conditions so

why are these autopilots disconnecting

and why are some single pilot Crews

having an especially hard time managing

the aircraft and re-engaging the

automation once the autopilot has

suddenly and surprisingly kicked off on

you and if we go back and look at at

this NTSB report from an accident back

in 2017 regarding a pc12 in a part 135

Air Taxi commuter accident situation

they give a good breakdown of some of

the limitations of the pc12 autopilot

now some of these limitations may change

based on exactly which Mak model of

patus pc12 you're flying the ntsp

probable cause from this 2017 accident

was the Pilot's loss of airplane control

due to spatial disorientation during the

initial climb after takeoff in night

instrument meteorological conditions and

moderate turbulence and this was

preceded by an autopilot

disconnect on the PC2 you control the

autopilot the mode of the autopilot

using this panel up

here here on your flat screen display

the results of what you put into the

autopilot are displayed up here in the

upper portion of your flat screen

display telling you exactly what mode

the autopilot is in and here on the Yoke

are a series of buttons that help you

manage the autopilot and especially

important is the big red autopilot

disconnect button located right here

next to the big red autopilot disconnect

button is a trim

switch you engage the autopilot on the

PC2 by pushing the autopilot button

located right here on the flight

guidance control panel as long as the

aircraft is within limits for the

autopilot the autopilot will

engage you can disengage the autopilot

by pushing this autopilot button again

or by pressing the big red autopilot

disconnect button located on the left

side of the

Yol the pc12 also has a trim trigger on

the control wheel where if you want to

temporarily disconnect the autopilot and

manually retrim the aircraft that'll

allow you to do that without completely

disconnecting the autopilot and Y damper

so if you pull in the trim trigger the Y

the autopilot is temporarily off the Y

damper remains engaged you can trim the

aircraft and then release the trigger

and the autopilot is back

on this is important because on most any

airplane if you attempt to trim manually

trim the aircraft with the autopilot

engaged the autopilot will

disconnect the autopilot will also

disconnect if the trim interrupt switch

is pushed that's the button you push in

the event of a runaway trim to stop the

trim from moving that'll disconnect the

autopilot or if the alternate stabilizer

TM trim switch is set to up or down

that'll kick off the autopilot a loss of

power to the autopilot computer or the

trim adapter occurs that'll kick it off

the monitors within the autopilot

computer detect a failure or the

following autopilot monitor limits are

exceeded but there's one additional

thing that'll kick off the autopilot

guaranteed every time that's not

mentioned in this list and that is if

you stall the aircraft even briefly so

these are the limits of the autopilot if

you have a roll rate greater than 10°

per second the autopilot will not will

disconnect and it will not reconnect

pitch rates more than 5 Dees per second

or accelerations outside of a plus 1.6g

or I think that's supposed to be a

negative

.3g envelope so if you get this is where

the autopilot kicks off in turbulence if

you get into turbulence and you exceed

these G limits which is quite easy to do

in turbulence

the autopilot will kick off now if you

get yourself disoriented and and start

maneuvering the aircraft a lot outside

of these limits the autopilot will not

re-engage the pc12 has two angle of

attack veins located one on each Wing

unlike Boeing

737

cut the PC2 has two independent angle of

attack veins located one on each Wing

when both of these angle of attack

indicators agree that you have exceeded

the critical angle of attack of the

aircraft it will sense the stall and

tell you that the aircraft is

stalling if the aircraft enters

installed condition even if

temporarily for example in turbulent air

conditions the autopilot will

disconnect normally if you want to climb

up to altitude in the pc12 you set your

altitude and the altitude window here

and then you engage the speed mode of

the autopilot which is similar to flight

level change for you boing guys and then

the aircraft will hold that speed and

you select a speed that's normally 20 or

more knots above your best rate of climb

speed to give you a good buffer from a

stall margin while you're climbing and

you set your power and it'll give you

whatever rate of climb you can get at

that power setting to hold that speed

and give you speed protection but in

turbulent air conditions you can get a

gust of wind or a brief wind shear that

even at that speed you can briefly

exceed the critical angle of attack of

the wing especially if you're

heavyweight because you're heavyweight

climbing out you're already fairly close

to the critical angle of attack you hit

a good gust of wind and you can

temporarily briefly stall the aircraft

and the autopilot will kick off and it

can be a cacophony of events in the

cockpit you can hear stall stall stall

and then autopilot disconnect and then

the associated autopilot disconnect

warnings now these stalled this

condition where it just hits you

suddenly and then the aircraft recovers

very quickly is not enough of a stall to

engage the other systems on board the

pc12 which include a stick Shaker and a

Stak stick Pusher but it will disconnect

the autopilot and if you're single pilot

IFR and not really up on your instrument

meter meteorological conditions flying

skills this can be a very surprising and

disconcerting

situation because when the autopilot

disconnects these are some of the

different warnings you're going to get

in the cockpit the cause system they

mention here caws is the central

advisory warning system so on the mode

control the autopilot caption flashes

four times and turns off on the cause

display unit the Amber autopilot dis

disengage message illuminates for 3

seconds and uh on the E AI the red

autopilot caption flashes five times

then turns off and the autopilot

disconnect warning tone is annunciated

in this is annunciated in the

loudspeakers and the headsets and the

cause gong warning tone is also

enunciated so suddenly the cockpit is

kind of lit up like a Christmas tree and

all sorts of warnings are going off and

the only way to turn All These Warnings

off is you got to reach up and hit the

auto pilot disconnect button to turn all

this stuff off so aviate navigate

communicate the first thing you got to

do is jump on the gauges and fly the

airplane and disregard all these

warnings for a second because you know

what it is you should know what it is

the autopilot disconnected but it

surprised you in this particular

situation so the next thing you're going

to need to know through your training is

to turn all that racket off by hitting

the red autopilot disconnect button on

the

Yoke now once you get the aircraft under

control with a known pitch and power

setting and the autopilot warnings all

turned off now you can go about

reselecting re-engaging the autopilot as

long as you're within limits of the

autopilot

limitations and continue on with the

flight but if you begin to struggle with

wondering what is going on with your

automation if all of these warnings are

throwing you for a loop you can quickly

and easily begin to lose control of the

aircraft if you fail to fly the aircraft

first and if you're a Private Pilot or a

commercial pilot that is transitioning

to the for the first time to something

as big and complicated as the pc12 this

is why you need to go to school a

professional training program maintain a

professional training program every

every year to remain current and

proficient in this complicated level of

an aircraft talking to my friend Jerry

Clemens of Clemens Aviation insurance he

requires that if you're going to own one

of these pc1 12s that you're going to

have to attend formal training in either

simcom or flight safety and if you're a

relatively low time pilot you're going

to need to fly with a mentor pilot for

150 to 200 hours an experienced rated

pilot in the PC 12 in all sorts of

conditions before you get very familiar

with the flat panel display and the

management of the Automation in this

aircraft and as my friend Hoover said in

his 17-minute video on the neand plane

crash if you can afford something like a

PC 12 at least you can afford a second

pilot to fly with you or a professional

pilot to fly the aircraft for you thank

you so much for your support of this

channel especially the folks over on

patreon that make this content possible

see you here