[Peetwo]

VH-ZEW C172 fatal - ATSB Final Report released.

Via the ATSB website: https://www.atsb.gov.au/publications/inv...Ag.twitter

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What happened

At about 1410 Eastern Standard Time on 8 September 2015, the pilot of a Cessna Aircraft Company 172S, registered VH-ZEW, departed Point Cook Airfield, Victoria, on a solo navigational training flight via waypoints that included Ballarat Airport, Victoria. GPS data showed that the aircraft was on the third leg of the planned journey, cruising at about 3,000 ft above mean sea level when it started to descend rapidly. The aircraft impacted rising terrain at about 2,200 ft and was destroyed. The pilot who was the sole occupant, was fatally injured.

What the ATSB found

The site and wreckage inspection identified that the aircraft impacted terrain in a level, slight right‑wing low attitude. That indicated that the pilot likely stopped the aircraft’s descent and started to initiate a manoeuvre to avoid the terrain. It is likely that the pilot manually manipulated the controls while the autopilot was on and engaged in a vertical mode. As a consequence, the autopilot re-trimmed the aircraft against pilot inputs, inducing a nose-down mistrim situation, which led to a rapid descent. The aircraft’s low operating height above the ground, due to the extent and base of the cloud, along with rising terrain in front of the aircraft, gave the pilot limited time to diagnose, react, and recover before the ground impact.

There was no advice, limitation, or warning in the aircraft pilot operating handbook or avionics manual to indicate that if a force is applied to control column while the autopilot is engaged, that the aircraft’s autopilot system will trim against the control column force, and possibly lead to a significant out of trim situation. Training requirements for autopilot systems was rudimentary at the recreational pilot licence (RPL) level due to stipulated operational limitations for its use. At the time of the accident there was no regulatory requirement for pilots to demonstrate autopilot competency at the RPL level.

What's been done as a result

The ATSB issued safety recommendations to the aircraft and autopilot manufacturers about the provision of limitations, cautions and warnings for autopilot systems and audible pitch trim movement.

The flight training organisation updated their operations manual, as a result of flight testing they conducted, to include warnings about the operation and function of the autopilot system absent in the manufacturer’s documentation. The hazard of manual manipulation of the flight controls with the autopilot engaged was also emphasised to students.

Safety message

Technologically advanced avionics and autopilot systems are now often fitted to general aviation aircraft used for flight training, private and charter operations. It is essential for all pilots to develop a thorough understanding and operation of all systems fitted to the aircraft they are flying. It is also important that student pilots consolidate manual flight and navigation skills before using the advanced auto flight modes or extensively using autopilot systems. Avionics and aircraft manufacturers should increase pilot awareness of automated systems by providing written warnings surrounding known issues and including visual and aural alerts in auto flight systems to increase pilot awareness of non-standard inputs. Fundamentally, pilots should be aware that if the automation is not performing as expected, then the safest option under most circumstances is to disengage the system and manually fly the aircraft.


VH-ZEW main wreckage. Source: ATSB



Source: ATSB

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And surprise, surprise this ATSB AAI actually included the very rare promulgation of 2 safety recommendations... :

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Safety issue description

The lack of manufacturer written advice, limitations, cautions, or warnings (written or aural) about autopilot response to manual pilot control inputs meant that pilots may be unaware that their actions can lead to significant out of trim situations, and associated aircraft control issues.

Response to the safety issue by Cessna Aircraft Company

The functionality described is true of virtually every autopilot [fitted to FAR 23 certified aircraft]. The type of autopilot behavior being discussed is covered in chapter 4 of the Federal Aviation Administration’s Advanced Avionics Handbook (FAA-H-8083-6, attached). The first page of the chapter discusses autopilot concepts and in the “How to use an autopilot function,” says, “Allow the FD/autopilot to accomplish the modes selected and programmed without interference, or disengage the unit.  Do not attempt to “help” the autopilot perform a task. In some instances, this has caused the autopilot to falsely sense adverse conditions and trim to the limit to accomplish its tasking.  In more than a few events, this has resulted in a total loss of control and a crash.”

ATSB comment/action in response

Knowledge is imparted in a number of ways, which include reading operating manuals, conducting training, communicating with experienced pilots and learning from one’s own experiences.

Advanced avionics and autopilot systems are now fitted to a significant number of primary training aircraft, such as the Cessna 172S (VH-ZEW). The level of knowledge that individual pilots have in this environment starts at a low base level and builds over time. The ATSB contends that student pilots are not likely to be aware of issues surrounding manual manipulation of the flight controls with the autopilot on. It is therefore important to implement methods that enhance pilots’ awareness of the issue, including aircraft and avionics systems operating manuals having the requisite limitations, cautions and warnings in place.

It is clear from the content of the FAA handbook that they believe a warning about the issue is required. Although the handbook provides very good educational material, it does not take the place of aircraft operating manuals as a reference guide.

The G1000 avionics and GFC700 autopilot systems are fitted to numerous aircraft types. Some flight manuals include limitations, cautions and warnings and some do not.

Additionally, there were no audible warnings provided for mistrim to enhance pilot awareness in the G1000 avionics system with the GFC 700 autopilot fitted, despite that being a feature of the superseded autopilot system.

As a result, the ATSB has released the following safety recommendation.

Recommendation
Action organisation: Cessna Aircraft Company (Textron)
Action number: AO-2015-105-SR-004
Date: 17 April 2018
Action status: Released

ATSB safety recommendation Cessna Aircraft Company (Textron)

The ATSB recommends that Cessna Aircraft Company, in conjunction with Garmin, implement changes to their operations manuals so that all aircraft types fitted with their autopilots have the limitations, cautions and warnings applied consistently.
 
 
Current issue status: Safety action pending
 


Last update 17 April 2018 

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Safety issue description

The lack of manufacturer written advice, limitations, cautions, or warnings (written or aural) about autopilot response to manual pilot control inputs meant that pilots may be unaware that their actions can lead to significant out of trim situations, and associated aircraft control issues.

Response to safety issue by Garmin

The avionics manufacturer indicated that since all autopilots work the same way, it was common knowledge for pilots not to manually manipulate the flight controls with the autopilot on. Therefore, any advice, limitations, or warnings about the issue would not be required. They also indicated that the presence of a limitation, warning, or caution is generally left up to the certifier of the equipment in the airplane [in this case Cessna].

ATSB comment/action in response

Advanced avionics systems and autopilots are now fitted to many aircraft used by relatively inexperienced pilots. Therefore it is important that every opportunity is taken to inform them of the potential danger posed by manual manipulation of the flight controls with the autopilot on.

Recommendation

Action organisation: Garmin
Action number: AO-2015-105-SR-006
Date: 17 April 2018
Action status: Released

ATSB safety recommendation Garmin

The ATSB recommends that Garmin, in conjunction with aircraft manufacturers, takes action to ensure that all aircraft types fitted with their autopilots have the limitations, cautions and warnings documented in the aircraft’s operating manuals. Further, the ATSB recommends that Garmin consider the use of audible warnings to enhance pilots’ awareness of mistrim situations brought on by the autopilot system.
 
 
Current issue status: Safety action pending
 


Last update 17 April 2018 

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There was also a MR accompanying the release of this AAI Final Report: 17 Apr 2018 [News Item] Know how your aircraft’s avionics and autopilot will react.

Finally here is the other Aunty's take on this report:

Autopilot incompetence may have played role in RMIT student's fatal Cessna crash: ATSB
ABC Ballarat
By Charlotte King
Tue 17 Apr 2018, 4:39pm



Photo: The crash site in Millbrook near Ballarat in September 2015. (Supplied: Air Transport Safety Bureau)

Aviation authorities have found a student pilot who lost control on her first solo navigation flight was not formally assessed on the autopilot function.

The 19-year-old RMIT student, who has never been publicly named, died in September 2015 when the Cessna she was flying in crashed into a Millbrook paddock, near Ballarat.

More the two years on, the Australian Transport Safety Bureau (ATSB) has released its report into the accident, finding the aviation student's efforts to manually control the aircraft while it was in autopilot mode are likely to have led her to lose control and nose-dive into the rural property.

The ATSB's executive director, Nat Nagy, said the crash raised serious concerns.

"It is now common for general aviation aircraft to be equipped with autopilot systems," Mr Nagy said.

"And while these systems can be very useful, it is vitally important that pilots understand how the systems will react in different circumstances.

"If automation is not performing as expected, then the safest option under most circumstances is for them to disengage the system."

The ATSB revealed it was not a requirement for trainee pilots to demonstrate knowledge of the autopilot and its limitations.

"The pilot's underpinning knowledge of the autopilot system could not be ascertained due to the absence of formal assessment," the report said.

In July 2017 the Civil Aviation Safety Authority introduced an element into the Flight Examiners Handbook, which requires pilots to demonstrate knowledge of the autopilot system when they are assessed for a Recreational Pilot Licence.

The ATSB also expressed concerns over the absence of warnings in the manufacturer's manual for the Cessna 172 — commonly used as a primary training aircraft.

"It was likely that the inexperienced pilot was not aware of how the autopilot would react to manual control inputs," the report stated.

"The inclusion of limitations, cautions and warnings in the aircraft documentation … would likely enhance pilot awareness of such situations."

Autopilot warnings now included in manual

The flight training organisation involved in the young pilot's aviation course with RMIT has updated its operations manual to include warnings about the operation of the autopilot system — warnings that are absent in the manufacturer's documentation.

The avionics manufacturer, Garmin, told the ATSB that it was "common knowledge" for pilots not to manipulate the flight controls with the autopilot on.

RMIT has meanwhile amended its standard operating procedures to include a warning to pilots that loss of control is possible if a pilot tries to manually override autopilot.

The university said its community was "devastated" by the accident, and said "the ATSB report confirms that RMIT followed procedures and was operating within regulations, [but] out of respect for the family, we won't be commenting on the report any further".

MTF...P2