Testing Autobrake Performance

Hello everyone!

So I was curious what the stopping performance was for each aircraft was using both autobrake settings.

My method:
• Spawned on the APP to 27R at EGLL, with standard atmosphere conditions (I defined that as wind calm, 15°C, CAVOK8
• Landed the B738, B752, B772, and A220 each a total of six times, three times with autobrake low, and three times with autobrake medium.

Note that for consistency:

  1. No reverse thrust was used
  2. APPR was used to make sure landings were all identical
  3. For every approach in one aircraft, the same airspeed was used

My results… basically the distance is negligible, particularly with the smaller aircraft. It looked to me as if the bigger the aircraft, the greater the difference in stopping distance between LOW and MEDIUM settings. However, the distance was still pretty negligible.
On the 737, the distance was literally the same.
I don’t know how I could actually measure the data, but on the 737 it stopped between exits A9E and A9W (for those who want to look at the chart).

Any ideas why it was such a small difference? Anyone else want to try

5 Likes

Departing is going to take twice as long due to people doing aborted takeoffs 🤣

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Oh yeah, didn’t even think of that 😂 people are gonna be testing this out on ES at a busy event 🤣

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For sure. 😂😂😂

And probably get kicked by the controller (pretty sure that’s a thing right?) unless there is actually a runway incursion or something.

Just out of curiosity: what does auto rake actually control? So far I only got that it controls your spoilers, but does it also control your (rudder) brakes? Because otherwise I don’t know how different deceleration values are achieved. But at the same time it doesn’t show any value on the rudder brake when slowing down so I am not to sure

On landing,when you have it on,around 3 seconds after throttle is idle,the brakes automatically deploy!

The Auto Brake System evaluates required braking action to maintain the following deceleration rates:

  • LOW: 5.6ft/s2
  • MED: 7.2ft/s2
  • MAX: 14ft/s2 > 80 kts & 12ft/s2 < 80 kts.
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I tried max autobrake and it nearly yeeted the 737

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And if I touch the rudder brakes, the auto brake system will be disabled, right?

Auto Brake will disengage when more than 30% of rudder brakes is applied.

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Hahaha that was funny.

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