I happened to register for Lufthansa account a few weeks after receiving my doctorate. I rather naively put Dr as a title. Only after I did so, did it dawn on me that if they ever need a doctor on board they might approach those with such a title first… unfortunately I would be of very little use in a medical emergency.

That slightly irrational fear has prevented me from adding it to any other accounts, so I remain Mr Squawk to BA and most others.