As I reported earlier, the McCain campaign has declined to publicly release the senator's birth certificate. But a senior campaign official showed me a copy of his birth certificate issued by the "family hospital" in the Coco Solo submarine base. (McCain's grandfather commanded the Coco Solo Naval Air Station in 1936; his father was the executive officer of a submarine based in Coco Solo.)
The birth certificate was signed by Captain W. L. Irvine. I have now checked that name against the Naval Register for 1936, and I find that William Lorne Irvine was director of the medical facility at the submarine base hospital in Coco Solo, Panama Canal Zone, during that time period. You can see the entry here. I think this effectively disposes of any remaining doubts that McCain was born inside the Canal Zone.
If he was born in the base family hospital he was born on the base, not just in the canal zone. Which may or may not make a difference depending on the law then in effect.
Or he may have been born in his parents quarters, with someone from the hospital staff in attendance. Wouldn't be all that unusual for that era.
That latter option seems to comport with some of the things his mother is said to have related, such as hearing the celebration of his birth in the nearby O-club from her bed. But maybe the O-club was next to the family hospital?