Airbus Support Costs - Concorde
Just a few sample figures recently published in some aviation journals:-
"New cockpit security doors cost as little as $25,000 for a Boeing aircraft, but $300,000 for Concorde"
"AF Concordes would soon require terrain awareness and other near-term mandatory upgrades costing some
$40 million - far more than fitting to modern aircraft"
As mentioned elsewhere, with comparative figures like these, I'm amazed (and pleased) that Concorde has been operational for so long.