There should be enough time to walk across if you’re booked through.

you wont go thru security again at heathrow assuming you are flying with BA you will land in terminal 5 and stay there until your next flight

You can always explain and ask to skip ahead in the line if you are delayed

The airports are fined by the airlines for any late boarding passengers as part of the service contract, so they do scope the security queues and fast forward people who they need to get through quickly. The timings are calculated to work so unless you faff about for ages in duty free you should be fine.

ive done edinurgh-heathrow-new york 3 times with BA in the past 6 months going through terminal 5 and only need to redo security on the way back - never needed to do it going

If you booked it as a single flight, there should be enough time between arrival at Heathrow to departure for LAX for you to catch your connecting flight.

If the flight from Glasgow to Heathrow is delayed, as soon as you get to Heathrow and deplane, find a member of staff and tell them about your connecting flight. They can assist to get you to the gate as quickly as possible. This might include calling a buggy to ride in and escort to front of queue at security screening.

(On some flights, that have been very delayed, the pilot will actually tell everyone to stay seated and let all those with a leaving soon connecting flight to city X deplane first and look for a staff member already there to escort you in the terminal. I’ve had that a few times where the airline has been proactive. Most times though there’s been no staff in the terminal and it’s been a mad sprint to the connecting flights gate so not saying this is usual).

If you are so delayed you miss your connecting flight you go to the airline desk and they will book you on the next available flight that has a seat. If this involves a long wait they will give you food vouchers or if no flight until the next day, they will put you up in a hotel overnight. I’ve had this happen a few times and once was actually upgraded to first class on the next flight.

coming back you will still be in terminal 5 and will follow the signs for flight connections, security is a breeze and its only for people making connecting flights, took me about 5 mins to go thru last week, its more a pain in the arse having to get everything out again

Sorry, this does not make sense...... if there is delays at this are the airline of me as passenger that I'm there?

When you check in at Glasgow, going to Heathrow on to LA, your bags will be checked on all the way to LA.

You get to Heathrow, watch the departure gates for your flight to LA and wait. Could be some hours, so time to get a bite to eat, use the loo and browse in the shops etc.

Airports are 24/7. Had a good laugh and bonded with someone at LA airport at 6 AM having a coffee while she was on her way to a friend - 5 hour flight! - for a weekend and already on the Tequila Sunrise. No judgement from me.

I love airports. The whole world meets there.

You shouldn't have to clear security again if you're flying in and out of the same terminal. Just follow the 'connecting flights' sign.

That said, if your first flight is late, the airline takes responsibility and will accommodate you on the next flight with available seats. As long as your connection is within the legal domestic-to-international MCT (minimum connection time), it is your responsibility to make the second flight, if the first one arrives on time. Of course there is some leeway if there are issues on the ground and the flight is missed due to reasons outside of your control, but it does depend on how benevolent the member of staff you deal with is.

Sorry I meant to say 'are the airline aware of me' as in are my whereabouts known IYSWIM?

The airline can't track you whilst you're inside the airport so they won't know exactly where you are, no. They would pass on information to their systems about your first flight being delayed though, if that was the case. Like a PP explained, this might be solved by offering you a quick ride between gates, or rebooking you on another flight if there's really no way of making the second one on time. But these will only happen if the your first flight is late leaving Glasgow or encounters a problem en-route.

I'm convinced I had to take hand baggage thru security again though?

Was it normal security - inside the same terminal - or the extra security check they do sometimes for flights to the USA? Last time I flew from LHR to Charlotte in the US, I had a second luggage check as I approached my gate. I wasn't even connecting, they had just decided to check everybody twice.