SIDSTAR asks...
1. Why would any pilot leave the Thrust lever at CLB
"One Engine Inop" type mindset leading to only holding one T/L? I don't subscribe to DozyWannabe's "fundamental misunderstanding of human psychology in the design of the interface" whatever that means - all the a/c I have flown have the same number of thrust levers as engines.
If I may be subtle for a moment .. no pilot would decide to leave one T/L at CLB on a normal landing, but he/she might for some reason as yet unexplained decide to retard only one T/L - perhaps by holding the Reverser Latching Lever in order to make a rapid selection on touchdown?
2. Why does the availability of autobrake depend on spoilers
Not sure this is the correct emphasis - operation of both depends on the conditions for Ground Spoiler extension being satisfied - why have another electronic logic chain for the Autobrake using exactly the same sensors? Using the SEC "Spoilers extension" signal to operate the Autobrake is entirely logical.
3. Why was this aircraft designed in such a manner that if the automatic deployment of spoilers fails for whatever reason, manual spoiler control is not available to the pilot when he most needs it - on the landing roll in limiting conditions.
Two points.. firstly the automatic deployment did not fail - conditions for deployment were not met.
Secondly because if it ain't safe to deploy them automatically it ain't safe to do it manually - the a/c was assumed to be airborne in CONF FULL.
Cheers, TP