Name vs initial

Middle names/initials don't matter.

Middle names are a US peculiarity. In Europe people don't always have them (I don't), or don't use them. It varies by country, it is more common to have a middle name in the UK, less so some other countries.
So, airline and other booking sites never bother to ask for them.

I have however come across US websites where the middle name is a required field and it gave me an error if I left it blank - very annoying ☺

I have a middle name and never include it or the initial when I book flights or trains either. It's never been an issue, dozens and dozens of flights, within several continents and between them.

In the past many airline and third party booking sites had limited space for inputting middle names. Today some have overcome that problem and some have not. We've had to do it with just initials and have never had a problem.

I was a little concerned recently on a domestic flight because the third party ticket seller only put Brad on my ticket rather than Bradley, as it is on my ID. Same thing, I called them and they wanted to charge a change fee. I didn't end up with any issues on the flights but it does prompt me now to be careful with a third party seller, where I probably log in as Brad, to make sure the name on the ticket is correct.

I think you have to be a little careful with first and last names - correct spelling etc. - but no middle names. I have a the "III" on my passport because it was pulled from my birth certificate 46 years ago. Never use it and never a question.

Try going by your middle name instead of your first name! Always have to remind myself to input the plane ticket info properly to match my passport.

Thank you everyone for the advice and support! I feel much more at ease about my upcoming travel!
Cheers!

A lot of the airlines have policies that, hey typos happen, and a few letters off is acceptable.

And some create their own issues. I can remember Virgin Atlantic deciding to append my middle initial to the end of my first name when I had a ticket with them. Looked ugly, but apparently it's how their system rolls.

Flying home from Charlotte last week, I had a boarding pass printed by American Airlines (I had accepted a bump from the flight the night before, so I was issued the printed pass and didn't have an electronic one). My name is long, so on the printed pass it had my first and last names, followed by "M." My middle initial is "J" as shown on my ID. The agent questioned me about it, and I responded that I thought the "M" was for "Mister." He called his supervisor, who was also confused and told me to go back to the American counter and clarify. I did, and the counter agent sighed and said, yes, it was for "Mister." So I trucked back to TSA, told them what the counter agent said, and showed them my electronic passes from flights the day before, which spelled out "Mr." They finally decided good enough and let me through. First time I've ever had any issue relating to the middle initial.

The previous day, leaving Jacksonville, going through the metal detector, I was treated to the random alarm and pulled aside and had my bags rifled and all my electronics swabbed for explosives. Most trouble I've ever had with TSA on any trip. But I just smiled and was pleasant. These guys are just doing their jobs, they have the power and it won't do any good to berate them. It's the price of travel today.

I have flown extensively for work and have always seen my first name coupled with my middle initial as if it were one name (Patriciah), this despite the fact that I had entered both first name and complete middle name when purchasing my ticket. At no time, including overseas travel, have I ever had a problem.