An indicator device for use in indicating whether or not a no-back device is operable, the indicator device comprising an indicator member 42 moveable between a first position and a second position, a biassing arrangement 56 being provided to urge the indicator member 42 towards its first position, and a latch arrangement 46 being provided to allow the indicator member 42 to be held, against the biassing load of the biassing arrangement 56, in its second position, the indicator member 42 being adapted such that, in use of the associated no-back device, movement of the pawl 30 of the no-back device causes the indicator member 42 to be moved out of its second position.