Name discrepencies between passports

Question

I'm a French-Italian bi-national

My main, French, passport is currently unavailable and I need to travel, so I'm using my Italian passport but both are different

My French passport correctly refers my three given names (in the 'Nicolas, Given Name 2, Given Name 3 FORMICHELLA' form) as does my birth certificate but the Italian registry didn't do that when registering my birth and so I have a single name ('Nicolas FORMICHELLA') from the Italian administration standpoint.

When booking flights, getting visas... I'd always fill all my names in the forms as written in my French passport but that causes a problem for my situation

Can I travel with the Italian passport? Or do I need to contact the airline for them to change my names to the single one?

And for the other way around, If I ever fill a form without the names and only my single name, can I use my French passport there?

Note: I'm talking about travel booking and not visas as you of course need to match the passport

Answer 1

Normally, airlines don’t care about further first names or ‘middle initials’; you can simply use a single first name for booking (and have a matching passport or ID).
There are probably some minor exceptions, especially when you travel in the US, and want to use TSA Pre or CLEAR - they expect a full match with all first names. You could still travel, you just might not get TSA Pre.

This is different for Visa (and Visa Waivers, etc, like ESTA) - usually the names must match completely and fully.