Great analysis, really interesting!
As you mention, I think the loss of transatlantics and US flights is the most stark. Is there another European airport that had scheduled US service in S19 that has completely lost it for S23? I was thinking STR, but I think DL are back there...maybe VLC? I doubt however that there are any that had 3 airlines/3 routes in S19 and now have none!
As you mention, c.155k seats to the USA lost and none replaced. Looking at it another way, 38k direct pax to the USA in Jul 2019, 6k Jul last year (85% loss) and likely the same this Jul. I won't compare to EDI (suffice to say it ain't good - and will be even worse in S23!), but how about MAN? It's lost about 60% of its US numbers Jul 19 to Jul 22, so a lot better than GLA. If GLA had a 60% loss we'd still probably have enough pax for a daily NYC plus 2w A330 to MCO.
Any suggestion that these pax have all disappeared or all prefer to fly to EDI seems pretty unlikely imo.
When you add in WJ and AC it's looks like a pretty spectacular failure to defend and protect this business - and replace what's lost. Given the numbers to Orlando pre COVID, it seems particularly inept to me that they've not got replacement service to MCO. We now have little more US numbers than BRS and NCL and iirc more direct pax to Mexico than the USA.
Consider also that the USA is Glasgow's largest inbound visitor market and the city is in the top 3 or 4 most visited UK cities by American tourists, so, despite Mr Bourienne's comments, on these routes there should be plenty inbound too. I posted in another thread signs that US visitor numbers to the UK are maybe above pre COVID, so even more of a failure - and a failure at the airport that must surely be bad for the city too given the importance of US visitors.
The ME flights don't seem great either. GLA still 1x daily, whilst EDI has higher frequency QR. BHX is back to 2x daily + QR back and Saudia starting and MAN has EK/QR/EY about back to normal, plus new Gulf Air to BAH and Kuwait airways to KWI.
Wrt to BUD it's interesting that GLA is also being sought at that end too. I think there are a few routes that operated for a fair while with plenty pax, which maybe suggests they could be reserrected - OTP, DUS, MUC, VCE. I guess some like DUS and MUC might have slot issues etc, but BUD, OTP, NRN, VCE could all be done by FR. Unfortunately it seems to me GLA STILL don't have a growth relationship with FR so even if EDI capacity is an issue, I think they'd be down the M77 tbh. You would think GLA would be desperate and want to prevent that, but it seems not.
I'd be more hopeful about EZY tbh. I notice they seem to be double daily CDG M-F now (and fares don't seem that cheap!), which seems pretty good given the recent failure of VY and Transavia.