The real problem, is cockpit interruptions, especially at outstations where we are less familiar with the local operations. And quite often, we have to read thru the stack of Notams, Wx etc while sitting sitting in the cockpit. Now the CM1 has to take the time to fire up the laptop, hope it is charged up and working, and then repeat the calculations when his time would be better spent... managing THREATS or TRAPS to the flight.
I agree that doubling-up on the calculations should prevent an INPUT error in the laptop but a thorough check of the data should do that as well. But doubling up on the calculations does NOT prevent omitting something such as an MEL item or a runway length adjustment and the likelihood of omitting such an item increases as the workload increases.
While the CM2 is inputting the data and patiently awaiting the results, I pull out the runway chart to reference the runway length and lineup criteria, review the latest ATIS and double check the page in the aircraft computer to make sure we have entered the updated ZFW. Then I verify that the takeoff weight is close to what the OFP predicted. AND I can sit there and think about things such as a wet runway, MEL item or review a Notam relevant to the LPC/OPT.
By the time the CM2 hands me the computer I have hopefully considered every eventuality and the time is available to thoroughly review the data, line by line. We are taught to Manage things as a Captain, yet now this procedure makes the managing process more difficult.
How many times have you calculated takeoff figures for 2 different runways because there is a probability of a runway change? Are we supposed to double up those calculations too? And if the runway change occurs while taxiing, then what? It is fair to say, that a runway change is a HUGE trap, and this new procedure is not suitable for such an event.
This FCI is a kneejerk reaction that does not address the real issue; DISTRACTIONS AND INTERRUPTIONS IN THE FLIGHTDECK. Regardless of how thorough and conscientious a pilot is, distractions increase the likelihood he will overlook something important.