Best plan would be to call your supplemental insurance company and ask them. Medicare gets a bit complicated in a hurry. Most/all claims of a US citizen with Medicare, require that the person receiving the services in Canada, pay the bill and then submit it for reimbursement to Medicare. There is language in Medicare that speaks to being in a "straight line" route between the Lower 48 and Alaska or visa versa. Now what this means to Medicare, appears to be subject to interpretation on their part. It also doesn't mean they will pay the doctor or the hospital, ambulance, etc. You will have to pay the bill up front and submit it to Medicare for them to consider reimbursing you up to the approved rate.
My Medicare supplemental policy only starts coverage after Medicare has paid their approved amount. I have yet to find out if this means that if Medicare turns down my claim of services received in Canada, then my supplemental doesn't pay either? Don't know the answer to that question and have not found anyone at my supplemental insurance company that knows the answer either.
Most folks, US Citizens, with any concerns about medical coverage in Canada will purchase travel insurance to cover them for that time period they are in Canada. You can google those companies that sell it. Some of the travel insurance policies will cover air evac out of Canada to get you back to a Medicare covered facility in the US. Some don't seem to cover this service.
The couple of times I needed medical care in Canada, I just paid the bill at the doctor's office and the pharmacy for the meds. It was a small enough amount, a couple of hundred at most, that I don't remember if my insurance reimbursed me or not. This was back before I was a geezer and old enough for Medicare. LOL
joe b.
Stuart Florida
Formerly of Colorado and Alaska
2016 Fleetwood Flair 31 B Class A w/bunks
www.picturetrail.com/jbpacooper
Alaska-Colorado and other Trips posted
"Without challenge, adventure is impossible".