Quote from
Centaurus:
"Difficult to accurately judge from the photo, but appears to be a relatively long time between touch-down and actuation of full reverse thrust. Readers know that reverse thrust is most effective at high speed. This means a fast manual selection of the reverse levers to full reverse immediately on touchdown. On slippery runways, and if wheel spin-up is slow, automatic speed brakes may not operate..."
Cannot disagree with any of that, as it more or less paraphrases parts of what other posters, including myself, have been discussing for the last 36 hours! (See posts above.) Can we assume you are using a small-screen internet device?
Quote:
"On slippery runways, and if wheel spin-up is slow, automatic speed brakes may not operate and it is necessary to raise the speed brake lever manually immediately on touch-down if max stopping capability is to be realised."
That sounds like good advice for some second-generation jets. However, in the case of relatively modern a/c, like the A310, the airbrakes are designed to go into ground-spoiler (lift-dumper) mode, in which the spoilers are raised to a higher angle than possible in speedbrake mode. On the A310, ground-spoiler mode raises all seven spoiler surfaces on each wing to 50 degrees. Speedbrake mode uses only four, and at a maximum of 20 degrees for the inboards and 45 deg for the outboards.
AFAIK, ground-spoiler mode cannot be commanded ad-hoc by the crew. They must arm it prior to landing, by raising a knob on top of the speedbrake lever, and then rely on its automatic deployment. (If the crew has failed to arm it, deployment can also be achieved if reverse is selected on at least one engine.) Deployment is normally achieved by the signal of main-wheel spin-up on touchdown (provided throttles at idle). However, my early manual gives bogie (truck) rotation plus RA less than 5 ft as a back-up signal, after a delay of 3 seconds.
Spoilers extension can all be monitored on the ECAM F/CTL page. If they fail to deploy, the problem with pulling the speedbrake lever is that - IIRC - the result will be full speedbrakes only (see above). They will have little effect compared with ground spoilers.