Would a creature that is only affected by the incapacitated condition still be able to fly?

Question

I noticed when reading Raulothim's psychic lance spell that it inflicts the incapacitated condition but nothing else. As far as I can remember, the incapacitated condition is usually seen as a "rider" to other effects/conditions and not usually seen by itself.

In order to make a flying creature fall, one of only a few specific things are needed:

If a flying creature is knocked prone, has its speed reduced to 0, or is otherwise deprived of the ability to move, the creature falls, unless it has the ability to hover or it is being held aloft by magic, such as by the fly spell.

The incapacitated condition doesn't mention anything that would meet those prerequisites and movement is separated from actions.

An incapacitated creature can't take actions or reactions.

Assuming the creature is not being held aloft by magic, would it still be able to move and not fall since the incapacitated condition, by itself, doesn't meet any of the qualifiers needed to stop the creature from flying?

I want to make sure that I'm not overlooking something because while this seems to be the case rules as written, it goes against my gut instinct based on what "incapacitated" means.

As an adjective:

Deprived of strength or power; debilitated.

As a verb

Prevent from functioning in a normal way.

Answer 1

A flying creature that is only Incapacitated may continue to fly, unless it is flying via a feature requiring concentration.

You've quoted the relevant rules. The things that make you stop flying are:

• "knocked prone"
• "has its speed reduced to 0"
• "is otherwise deprived of the ability to move"

However, Incapacitated only states:

An incapacitated creature can't take actions or reactions.

Being unable to take actions or reactions is not on the list of things that make you stop flying, nor is it implied by or an implication of any of those things, so a creature that is only Incapacitated may continue to fly.

I've emphasized that this applies when the creature is only Incapacitated because some other conditions, such as Paralyzed and Stunned, also come with Incapacitated, but would cause a flying creature to fall.

Now, there is an exception to the above ruling. If the creature is flying via a feature requiring concentration, becoming Incapacitated would cause the creature to fall. This is because the rules for concentration state:

The following factors can break concentration:

• [...]

• Being incapacitated or killed. You lose concentration on a spell if you are incapacitated or if you die.

For example, the spell fly states:

You touch a willing creature. The target gains a flying speed of 60 feet for the duration. When the spell ends, the target falls if it is still aloft, unless it can stop the fall.

If you cast fly on yourself, started flying, and were then Incapacitated, your concentration would be broken, the spell would end, and you would fall.

Answer 2

Thomas Markov's answer is pretty much correct, but I'd like to clarify something that I feel is missing in their answer.

The the rules for Incapacitated state:

An incapacitated creature can't take actions or reactions.

Flying is a type of movement, and moving is not an action in D&D 5e. As the rules for a turn state:

On your turn, you can move a distance up to your speed and take one action.

As said by BlueMoon93 in this answer, effects that incapacitate tend to restrict movement as well. His excellent example: Hypnotic pattern says:

While charmed by this spell, the creature is incapacitated and has a speed of 0.

The emphasis is mine on the last quote.