No you will need to add them to airbases for them to show ingame
Dependant on which mod you are using will depend upon which air bases are placed where.
You load the mission editor and then load the LND layer
example GWX
The floatplane base is in actuality the SmallAirBaseGe located in SilentHunterIII\data\Land\LAB_SmallAirBaseGe
Open the CFG file with notepad
example the GWX one
[Unit]
ClassName=SmallAirBaseGe
UnitType=406
MaxSpeed=0.000000
MinSpeed=0.000000
Length=1
Width=1
[AirGroup 1]
StartDate=19380101
EndDate=19450531
Squadron1Class=LBSArado
Squadron1No=1
You can add further AirGroups as below
[Unit]
ClassName=SmallAirBaseGe
UnitType=406
MaxSpeed=0.000000
MinSpeed=0.000000
Length=1
Width=1
[AirGroup 1]
StartDate=19380101
EndDate=19450531
Squadron1Class=LBSArado
Squadron1No=1
[AirGroup 2]
StartDate=19380101
EndDate=19450531
Squadron1Class=******** <-----Aircraft class name here
Squadron1No=2
Aircraft will now show in all areas the SmallAirBaseGe is placed