What speed do you have in the FMC to start with? In most cases it is the default 240kts below FL100.
Speed will (most likely) stay the same. Airspeed should be commanded by what is programmed/set or is the default in the FMC.
IF your speed was above/close to the max F1 speed, then the FMC will limit the speed to 5 kts below max F1 (280-5=275).
Also, assuming you were above the amber min maneuvering speed to start with? Otherwise A/T would have been actively protecting you and keeping you at/above that. So adding flaps to 1 should cause that speed to decrease. IF so, then speed would drop closer to whatever FMC speed is, but will still keep you above amber min maneuvering speed, and 5 kts below max flap placard speed.
Last edited by bigduke6; 23rd Sep 2015 at 04:56.