one of the Costco locations in San Diego, is the first / oldest of the business, was bought in 1976 and Price Club began. The first Costco was opened in Seattle in 1983, it merged with Price Club in 1993. The building was either a hanger, or a warehouse, for Hughes Aircraft manufacturing

"The airplane hangar was a building used by Hughes Aircraft Company as a manufacturing facility" says Chat GPT.

Further digging result:

The building was originally a warehouse (specifically Warehouse #401) used by the Hughes Aircraft Company, associated with Howard Hughes, as a manufacturing and storage facility. 

The structure, along with five other hangars, was part of a larger aviation industrial area.

However, there was a nearby airfield, just up the hills in Clairemont

Morena is at the bottom of the photo, this is all South of Balboa Ave, about a mile or two south of Costco. 

This earliest depiction which has been located of San Diego Airpark was a 1947 Howard Rozelle aerial view (courtesy of John Fry).

1947 San Diego Airpark. This very short-lived general aviation airport is now the long straight part of Clairemont Dr where you see the red arrow. There's a 7-11 there, and in the image below, all the apartment buildings have white roofs

https://www.facebook.com/groups/182165938517253/permalink/2929122417154911

https://www.airfields-freeman.com/CA/Airfields_CA_SanDiego_S.htm#sandiegoairpark