Have a look on this older thread:
viewtopic.php?f=74&t=18766This is the importand part:
FlyerSome units are able to fly higher and faster than ordinary Skimmers.
Formations where all of the units have this ability count as Skimmer and also behaves exactly like
Aircrafts with the following exceptions: During the approach move and the disengagement move they
have a Speed of 100cm but don`t have to move 30cm in order to turn (they can turn „on the spot“) .
Non-AA-units on Overwatch can shoot at them as if they where ground units of the appropiate type.
After the approach move units with the Flyer ability are treated as any other ground unit of their type.
In the End Phase they can disengage like Aircrafts but if they can't leave the board they aren't moved
and start the next Turn as ground units. A formation of Flyers can onyl choose Ground Attack and
Stand Down actions.
Independend TransportSome units can act independently as a transport for other formations than their own.
Formations where all of the units have this ability count as a single War Engine for transportation
purposes. A formation of Independend Transports can only transport one formation at any given time.
A formation of Independend Transports which are also Flyers and are off board and don`t transport a
formation can only choose a Ground Attack action with the intention to pick up a formation.