Overread wrote:As far as I see in the rules there are no rules that specifically cover being locked in close combat. Ergo if a model can disengage and move away it is free to do so so long as it ends its move more than 1 inch away from the enemy models. For a flying unit this means that they can fly over enemy units so long as it can fully move past them and complete its flight movement - and of course end up more than 1 inch away.
It is possible that the player is remembering old rules from previous editions of the game; or that there might be a special rule for close combat that their unit has in their codex.
When it comes to rules always take all rule materials with you to the game and if a query comes up take a moment to check them to make sure (in theory whoever makes a claim should show it in the book - however in practice it speeds things up if both players have a look provided that they've respective copies of the rules being checked)
Note Larks already provided the reference point.
It should be noted that there's nothing specific in the rules about disengaging. It's more that the movement rules don't stop you from moving if you are in close combat
The specific scenario of disengaging with a model that has the
FLY keyword not being covered is probably because the rules in the Movement section that cover
FLY and Falling Back work together to give you the tools. It doesn't have to be specific because the ability is inherent in the rules.
For fear that the thread may lead to an incorrect answer: Yes, you can fall back with the unit as described in the
OP.
Why?
Moving (Core Rules Leaflet, under "1. Movement Phase wrote:
[...]
If the datasheet for a model says it can FLY, it can move across models and terrain as if they were not there.
Falling Back (Core Rules Leaflet, under "1. Movement Phase wrote:
Units starting the Movement phase within 1" of an enemy unit can either remain stationary or Fall Back. If you choose to Fall Back, the unit must end its move more than 1" away from all enemy units.
[...]
The Fall Back mechanic just says that you must end your move more than an inch away, and the
FLY keyword allows you to move past them as though they weren't there. So long as you can fulfill the requirement of ending further than an inch away from any enemy units, you absolutely can Fall Back with a unit that has
FLY, even though it is surrounded by enemy models.
Edit: Valkyrie already got it! I'll leave this here just in case the thread is sought out in future.