Update: Tesla sent us a statement regarding the tests discussed in this article. You can see it in full below.

The Tesla Autopilot program can be confusing at times since it englobes a lot of different features like Traffic Aware Cruise Control (TACC), Autosteer, Autopark, Auto Emergency Braking (AEB) and others. While you can look into Tesla’s public literature on the features, like release notes and manuals, it is fairly limited.

There’s nothing better than some actual testing of the features to explore the limits of the program. A couple of Model S owners got together and did just that – though we wouldn’t necessarily recommend using their methods since jumping in front of a moving car is rarely a good idea.

A Tesla Model S owner going by ‘Kman’ has a popular Youtube channel and he releases videos about his Model S or related to his Tesla ownership experience. In his latest video (see below), Kman claims that he found “two serious flaws” in the Model S’ Autopilot system:

“The summon feature of the Tesla Model S worked flawlessly as designed, though the tesla autopilot and tesla traffic aware cruise control (TACC) failed to even attempt to slow or stop the vehicle. The Collision avoidance was a fail, so this crash test showed two very serious flats of the Tesla Model S collision avoidance software. I hope this does not cause any tesla accidents, and I hope an update comes very soon to prevent some Tesla Accidents.”

The first part of the video shows the Summon feature of the Autopilot detecting a pedestrian and either applying the brakes or steering away from him. Summon is used primarily for parking and only operates at low-speed.

The second part of the video is more problematic. Kman activates the TACC feature and on a second try both the TACC and Autosteer at 18 mph (the slowest speed for Autopilot to activate). On both tests, the system detected the pedestrian, but the Auto Emergency Braking didn’t activate:

What does seem to perform very well in the second part of the tests is the Forward Collision Warning. You can see the visual warning on the dashboard and hear the audible warning. Those are in place to let the driver know that a collision is likely if no one takes action, but this feature itself does not take action and Tesla made that clear in its owner manual:

Warning: Forward Collision Warning is designed only to provide visual and audible alerts (see Visual and Audible Feedback on page 58). It does not attempt to apply the brakes or decelerate Model S. When seeing and/or hearing a warning (described below), it is the driver’s responsibility to immediately take an appropriate action.

It is reminiscent of a recent Model S accident caught on video in Switzerland. The driver received the Forward Collision Warning, but he didn’t apply the brakes because he expected AEB to do it for him, which is of course something you should never do.

But still, it is unknown at this point why the Automatic Emergency Braking didn’t activate in both the accident and Kman’s tests since in both cases, Tesla’s Autopilot sensors were able to detect the obstacles.

Automatic Emergency Braking was introduced in Tesla’s 6.2 software update last year as part of the new Collision Avoidance Assist at the time. The important word here is ‘assist’. The system is in place to assist you in avoiding a collision, but you should never rely on it to completely do it for you.

The automaker described the feature in the release notes:

“Automatic Emergency Braking is designed to automatically engage the brakes to reduce the impact of an unavoidable frontal collision. Automatic Emergency Braking will stop applying the brakes when you press the accelerator pedal, press the brake pedal, or sharply turn the steering wheel. Automatic Emergency Braking is enabled by default.”

While it is enabled by default, you can temporarily disable the feature in the settings, but it will automatically re-enable next time you drive the vehicle. The feature also only operates when you are driving at speeds between 5 mph (8 km/h) and 85 mph (140 km/h). The tests and the accident appear to fit the requirements.

Tesla is always working on improving the feature. A couple of Model S vehicles were spotted conducting AEB tests at the Naval Air Station Alameda on San Francisco Bay earlier this year:

While you should always stay vigilant and never rely on Tesla’s Autopilot to avoid an accident, the system has been known to save the day a few times. Like when the AEB engaged to save a Model S driver from a head-on collision with a turning motorist on a dark rainy night in Seattle, or when emergency steering avoided a crash with a distracted truck driver: Watch Tesla’s Autopilot autonomously avoid a collision with a truck [Video].

Update: a Tesla spokesperson sent us the following statement in regards to AEB: Safety is a top priority at Tesla, and anyone attempting to purposefully strike another person or object with their Tesla is misusing the vehicle. It is paramount that our customers exercise safe behavior when using our vehicles, including remaining alert and ready to resume control at all times when using the car’s autonomous features, and braking to avoid a collision. More information on Automatic Emergency Braking: Model S and Model X are equipped with Automatic Emergency Braking (AEB), which is designed to engage the brakes at the last possible moment to avoid or mitigate a collision. AEB does not engage when an alternative collision avoidance strategy (e.g., driver steering) remains viable. Instead, when a collision threat is detected, forward collision warning alerts the driver to encourage them to take appropriate evasive action. AEB is a fallback safety feature that operates by design only at high levels of severity and should not be tested with live subjects.

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