Dual National leaving UK - Which Passport?

I recently checked my son in on his UK passport in the UK when flying to the US (I wasn't thinking), and immigration in the US gave me a really nasty speech about it when I showed them his US passport on arrival. The IO gave me a very strict warning to always use a US passport when traveling to the US.

My mom is booking and paying for our tickets from the US, but it's on KLM and we'll have to go from Glasgow-Amsterdam and then Amsterdam-Houston.

Do I still need to check in on our US passports for the Glasgow-Amsterdam (EU) leg of the trip?

We'll have friggin' NINE passports among us (two for each child and myself, DH on his UK one).

When you check in at Glasgow you'll be checking all the way through to Houston if you're travelling on the same airline or one of their 'partner' airlines (KLM is partnered with Northwest). So yes, you do need the US passports.

When you check in at Glasgow you'll be checking all the way through to Houston if you're travelling on the same airline or one of their 'partner' airlines (KLM is partnered with Northwest). So yes, you do need the US passports.

That sounds weird, to check in on US passports.

But will do.

On the way back, we check in on US passports as well?

You have to enter & exit the US on your US passports. I have always just handed over all of our passports just to be on the safe side.

On leaving the UK if you just hand over the UK passports they'll look for the ESTA clearance and not find it which is why you need both.

On leaving the US if you only hand over your US passports & you don't have a return ticket you may get asked where is your visa for the UK if you aren't returning to the US, which is why you need to show both.

UKBA (at least at LHR terminal 1) has started exit screening to make sure no one is evading immigration control trying to sneak out of the country, which is why I was questioned by them when I only produced DD's US passport and then had to get her UK passport out of my pocket. Not really a problem, but just carry all of them that way you're prepared for all possibilities.

I've not heard of a fine, but it makes sense to have the requirement.  Why should a citizen count towards visitor numbers?  What if someone decides to stay longer than their visa waiver/visitor visa?  It's their right as a citizen to do so, but it would show up as evasion/overstay, and could potentially waste resources sorting it out.

Just seems a bit simpler to have the requirement that people travel into a country that they hold citizenship to on that passport and be ready to present it on the way out as well.

Honestly, I don't trust airline staff to make the right decision.

Agreed!  I look at it as MY responsibility to travel on the correct passport, not the responsibility of airline or travel agency staff.  They are not the ones who will have to suffer the consequences...

I have been in and out of the US 7 times in the last 12 months (business - ugh!) and on 3 of those occasions, the travel agency had used the wrong passport details for my API, despite me reminding them at the time of booking that I hold two passports....     

Just an update, I used my US passport at the airline check-in and of course entering the US and it wasn't a problem at all. 

To clarify again, I'm an EU citizen, but not UK, so I had already left my home country when I entered England.