All available parking spots large enough for your aircraft are occupied by AI traffic.
Originally Posted by Shrikharan
It is not a bug but by design.
If you have added any AI traffic besides the default, this can be quite common - though it can happen with the default AI traffic and airports if you fly large aircraft almost anywhere.
NZAA - Auckland has parking for a maximum of four (4) heavy aircraft, 17 medium aircraft, 16 small gate spots, six GA medium and 13 GA small aircraft
OMDB - Dubai Intl has parking for a maximum of six (6) heavy aircraft, 43 medium aircraft, 41 small gate spots, three GA large, three GA medium and three GA small parkign spots.
GCXO - Los Rodeos has parking for no heavy aircraft, four (4) medium aircraft, 10 small gate spots, one medium GA and three GA small aircraft.
No one is going to pretend the default airports have sufficient parking for real world levels of AI traffic - though FSX is many, many times better than FS2002 and FS2004.
There are three programs available to allow you to modify airport parking spots, add more spots - Airport Design Editor and FSXPlanner require that your have FSX Deluxe with the BGLComp SDK installed. AirportFacilitator is payware.
You can download many modified airports - check the badly misnamed AFCAD section under FSX in your favorite file library.
Ray Smith has done NZAA and OMDB - and I trust his work.
I don't see anything for GCXO yet.
@ PawPaw's house - near KADS, Addison, Texas, USA