Compared to 767, A340 has 100% more engines. Losing an engine on twin leaves you with 50% of the power and losing an engine on quad leaves you with 75% percent. Or to take a look at the second segment climb requirements from the AEO perspective, during normal take-off, twinjet has to develop 100% more thrust than required to maintain required climb gradient (bar odd types with automatic RTO power), while quad needs only 33% more. So while 340s do climb and cruise slower than comparable twins, their performance is quite adequate and safe.
when we flex on the 767
Do B767 FLEX or ATM? It's only semantics question but I'd like to know if A-speak is starting to permeate B-company.