Configuration

These three exist for setting up a specific test rather than for use on frequency, because an aircraft manages its own configuration on an approach. None of them has a short form.

A setting you make holds while no approach is armed. Once one is, the aircraft takes its flaps back over: the approach logic re-decides the flap position continuously and does not know you set it. Gear and speedbrake stay as you left them until that logic's own decision changes.

The flap position is a step number, counting up from flaps 0 for clean. How many steps a type has is the type's own business, from two on a small twin to nine on a 737, so flaps full selects the deepest one without your having to know the count. A number past the last step selects the last one rather than being refused.

When an aircraft refuses

Flaps and gear are both limited by speed. For the gear it is the operating limit described under what an arrival does by itself. For flaps it is the placard of the setting you asked for, which is a different figure for each setting and falls as the flaps go further out.

A flap setting is reduced to the deepest one allowed at that moment, the gear simply stays up, and the reply names the limit that stopped it. Neither takes the rest of your line with it.

The speed this is judged on is the aircraft's airspeed rather than the ground speed on your tag, so expect the two figures to be some way apart in a strong wind or at height.