Strange to say, my last post that was deleted on this forum was about glider airbrakes coming open.
On a thread about an airliner taking off with not enough power, I realised it might be judged off-topic, but I thought it was relevant to people having the experience or awareness to perceive something amiss and finding the solution.
Years ago, as some airbrakes opened on the ground run and two of us ran towards a car with a radio, we overheard a conversation that showed we weren't needed. Have you got both mags turned on? Try closing the airbrakes!
This video, even if it's now gone from here, was seen by some of us, and can't be forgotten.
As someone says above, it might have been interesting to see from a bit earlier. Two queries arise with me. Is the movement of the trim a deliberate part of the checks, or duplication of a previous check, or an unwittingly wrong check of what was intended to be the airbrakes? And why continue to hold the release knob until well after the danger of ground loop or inadvertent sudden initial pull-up has gone?
If I'm interrupted during checks, or there's a delay and perhaps it's so hot as to open the canopy again, I do part of the checks again, canopy and brakes again, without worrying if it looks as neurotic or manic as certain tennis players' mannerisms before every single serve.
In some places, the person hooking the rope on will observe or actually ask if the brakes are closed and locked. If they obviously aren't, and it looks like an oversight or it's someone I dont know, I'll say so; they shouldn't be offended if they have to say they like holding them open for a few seconds at the start.
It has been phased out for the pilot to ask all clear above and behind, and give the take up slack and all out commands. Nowadays it is assumed if they are hooked on they are or should be ready to go. But there isn't an excuse to be a bit more casual; it should also mean don't hook them on if they aren't ready.
So perhaps any questions about concentration or routines extend slightly further than only the pilot.