This is one of the most extreme tests one could possibly do for through-checking/through-tagging...
Scenario:
1 PNR
6 oneworld carriers (BA/AY/CX/UL/MH/QF), all of which are Amadeus carriers
8 flights (AY*BA/AY/AY/CX/UL/MH/MH/QF), one of which was a codeshare AY operated by BA
3 tickets (AY/UL/QF ticket stock)
3 all day or overnight long transits
4 continents
9 airports (referenced as AAA, BBB, CCC, DDD, EEE, FFF, GGG, HHH and final destination BNE)
...spanning about 5 days in J, for all but 1 flight
Day 1: Checking in with BA at AAA
BA uses a coughpy check in overlay GUI called FLY. They spent large sums of money on it, it's slow, it has single points of failures, it's been the cause of 7 major outages/delays since it was implemented, one of which shutdown the airline for a day and a half.
Going through the document check function in FLY... on swiping an AUS passport, for final destination BNE, it thought that I was fine to travel through each transit port... but I supposedly couldn't enter Australia with an Australian passport! No way to override it. Fail...
I found out that BA outstation supervisors do have access to native Amadeus Altea (what virtually every other Amadeus carrier uses for departure control), so it was clearly a BA business decision to make an overlay GUI, except that the airport's shared computer systems would crash each time an attempt was made to access Amadeus Altea.
The end result was a handwritten boarding pass. We did manage to get a bag tag printed. Bag was only tagged to BBB due to an overnight at BBB. FLY did give the option to tag to every transit port, including the final destination BNE.
Being on a codeshare didn't have any effect on the above situation.
I did also see another passenger with one PNR and more than one ticket in the same PNR have their bags through-tagged to LYS, so BA connecting to AF connecting to AF. BA couldn't check in the AF flights, but had no issues tagging the bag through to LYS. This is against BA's own published policy interestingly...
Day 2: Arriving at the BA arrivals lounge
FLY spat the dummy again wanting to do a document check, even just to scan me into the lounge! It even froze up their computer. They let me in without bothering.
I discovered that BA staff at BBB all had access to native Amadeus Altea, just that they aren't really meant to use it (by means of not having been trained on how to use it!). They were happy to let me guide them on how to print my onward boarding passes which was easy to do.
Boarding passes were printed up to flight #6 (destination GGG). Attempting to force it to check in any further than flight #6 in the chain was a no-go (I attempted a number of methods that are possible). All 8 flights were visible just fine, inclusive of the one I had just alighted from.
Day 3: Checking in with AY at BBB
AY has contract staff (Menzies) at BBB.
I asked for the bag to be tagged to GGG. This would've been 5 flights and resulted in 2 bag tags for 1 bag (3 flights per tag). The system is capable of doing such a thing, though the contract staff gave me a spiel about how they aren't allowed to print more than 1 bag tag per bag, ie. tag for 3 flights only.
I accepted the tagging to EEE only (I had enough time to re-check anyway). Boarding passes were printed again, up to and including flight #6.
Day 3: Transiting with AY at CCC
I enquired at the transit desk at CCC whether AY contract staff at BBB were correct about not being to print multiple bag tags per bag and they confirmed what I already knew - multiple bag tags (ie. more than 3 flights) was perfectly fine.
At that point I asked for a 'BCO' aka baggage change order to be put in to spit out the bag at CCC. I exited to arrivals and had my bag within 15 mins and took the bag upstairs to re-check it. For the record, most airlines can do a BCO - but airline staff generally refuse to do them claiming it's not possible, which is untrue.
No issues printing the tag to GGG this time, as per my original request earlier in the day. They printed me another set of boarding passes... again up to and including flight #6.
Attempting to force through check in beyond flight #6 was still a no, even after having flown 2/8 flights.
Day 4: Transiting from AY to CX at DDD
No issues at DDD. CX confirmed the bag tag number was registered on their end.
Day 4: Transiting from CX to UL at EEE
No issues at EEE. UL confirmed the bag tag number was registered on their end.
Day 5: Transiting from UL to MH at FFF
No issues at FFF. MH confirmed the bag tag number was registered on their end.
Day 6: Arriving at GGG with MH
Bag didn't turn up on the carousel, but MH confirmed it had been scanned in at GGG not long prior. It was suspected it had fallen off a baggage cart or something enroute to the arrivals baggage belts.
Bag was found shortly after and re-routed on to HHH.
MH at GGG (6/8 flights flown at this point) were finally able to print a boarding pass for flights #7 and #8.
Day 6: Arriving at HHH with MH
Bag was collected at HHH and rechecked with QF to final destination BNE.
Summary...
1. Amadeus carriers can only through check in up to 6 flights.
2. The downline carriers (in this case AY, CX, UL) cannot force check in any further than the 6th flight in the chain, even after flying the first few flights. Effectively a new 'chain' starts from flight #7 onwards (presumably to flight #12 if it existed).
3. Any airline in the chain of 8 flights can tag bags through to the 8th flight's destination (BNE in this case). It is possible to tag bags through to a flight that you are not checked in on.
4. It is worth checking with each carrier enroute that they have your bag tag number(s) registered correctly.
I hope this illustrates what is truly possible when everything is on one PNR
