B777 Spoilers system

I was watching B777 landing video and I notice that when main gears touched ground it has two steps to deploy the spoilers. I curious that when or what will second steps of deploying spoilers trigger. Is it based of angle of aircraft or when you pull reverse or it’s timed. It will be super helpful if you know something!


Most aircraft will utilize what we refer to as “WoW” or Weight on Wheels. Sometimes its weight on wheels + a specified time (in seconds) at which these will trigger.

If spoilers deployed right away, imagine if an aircraft came in for a landing and bounced. When it bounces, it’s airborne slightly. Because spoilers destroy lift and the airflow, you’re dropping the plane back down onto the pavement, and depending on how high the bounce was, you could be looking at some structural issues.

So as a built in safety cushion, spoilers will deploy with a slight delay.


Might have to do with crosswind, as explained here for buses :

Edit : just what Deercrusher explained!

So, spoilers deploy after totally touched down or first touch?

They would fully deploy once you have weight on the main gear and say for 3-5 seconds.


If the pilot has activated “ brake to vacate” the aircraft’s computer will use:
Variable Spoilers
Ailerons as spoilers
Variable Brakes
Variable reverse thrust
To achieve a certain speed at the desired exit based on aircraft weight, airport attitude, wind, and runway condition.
And the operator company can adjust the balance of the 4 braking options. Eg brakes preferred over reverses or the other way.

Nearly impossible to see tow same landings regarding spoilers and ailerons. But typical is spoilers only with weight on wheels of MLG as mentioned above, and ailerons as spoilers not before weight on nose gear and not with excessive crosswind.
A wide field of options.

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i’ve seen the use of ailerons as spoilers before and it was weird to see that 2 parts of the plane usually doing the exact opposite of each other are both going up.

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