That's a rather vague question - why are you relocating - why is this even an issue at their advanced ages?

Having lost the dog who was the love of my life this summer, I would first ask whether they are in particular danger from the flight. If so, is there possibly a chance you could pay someone to drive them? How far is it? You can pay someone to drive your car -- can you find someone to drive them? I would say if they are so infirm or feeble that you worry about them making the trip, them maybe you should be with them at the end, no matter how hard. And let me tell you it's hard. But the sand ending is the price you pay for a lifetime of love.

If you are absolutely certain they cannot survive the cargo hold, then do it before hand so that they do not die alone

if they truly would not survive a plane journey then humanely in your arms

Why do you think they would die in the hold now vs. when they were younger? And let me follow this by saying I have a tremendous amount of experience shipping dogs in cargo. All of mine survived just fine, bounced out at the other end, and all was well. If we're talking about loading a feeble 15 year old in CHF on the plane, that's one thing, but a healthy oldster with no major underlying health problems can fly just fine unless it's a breed that falls into the high risk group.

Except , they might NOT die in the plane ...

I’m very sorry you have such a difficult decision to make. At least with the humane option, they would be in your arms.

Humanely. And I am very sorry. That is painful.