Single engine climb gradient
NO .. only one engine out climb gradient taken into consideration.
Infamous incident on a Trident 3 airborne from Malaga iirc and lost an engine shortly afterwards. Crew didn't check the WAT performance before they diverted to Madrid, typical useless atc for that time lined up an Iberia which forced a missed approach. Aircraft continued descending; skipper fortunately cleaned up to min drag (230 knots?) and accelerated down the valleys which gave him enough performance to return to land.