Should be no problem, look for the transfer counter the moment you deplane. Don't follow the crowds. The transfer counter will issue/validate the BA boarding pass and point you to transfer security.

The transfer desks are just before the Immigration hall. No need to clear immigration. Transfer desk will validate boarding pass and hopefully provide the lounge invite. If you don't get a lounge invite - head to GVK Lounge (they can page BA staff to come and authorize your entry). You have more than enough time to connect (its the same terminal)

Hello BOM connection experts,

I'm traveling HYD-BOM-SIN, making a domestic to international connection from 9W452 to SQ423 with a scheduled 3.5 hours in BOM (arrive 8:00PM, depart 11:30PM). While I'd typically be comfortable with this, it looks like recent flights have had a poor on-time arrival record (many leaving HYD late and spending 2 hours in the air holding outside of BOM instead of 1.25 hours), so I'm trying to form a solid back up plan (I have an onward connection to catch in SIN). All of my flights are on a single ticket (issued by UA). Here's what I'm wondering:

1. What's the absolute latest that I can arrive in BOM and still make my interline connection? I'm thinking that if I'm off the plane in BOM by 10:00PM, I can probably catch my flight, and any later and I risk being rejected at the SQ check in counter (I'm not sure if I'll be able to print my SQ boarding pass in advance, but I'm going to try).
2. If I'm delayed leaving HYD, at what time should I start trying to get rebooked on the nonstop MI HYD-SIN flight? My concern about an attempt to take this approach is that 9W may not update the delayed departure time leaving HYD early (and often) enough to know that I'm going to misconnect before I get on the plane in HYD.
3. If I follow the signs to international transfers at BOM, will I get dumped out into the main check in hall upstairs, or is there a transfer desk somewhere that I haven't noticed before?
4. If I arrive BOM too late to make my scheduled SQ flight, there's a 9W flight to SIN around 1:15AM that would give me a 20 minute connection in SIN, so I'd probably need to rebook my onward flight from SIN as well. Should I cut the middleman and get on the phone with UA as soon as I land in BOM to sort this out, or am I stuck working with 9W once I misconnect? If so, is the 9W check in desk (upstairs after passing through domestic baggage claim) the correct place to go?

Thanks in advance for the help!

1. Check-in closes 60 minutes prior usually, check what the SQ cut-off is. If you're on one ticket you should get onward BP in HYD
2. Monitor the delay, I've had a missed connection in BOM due to delay in HYD and still at check-in in HYD requested rebooking on 9W to AUH then EY to JNB then CPT (original ticket was 9W to BOM, then SA to JNB then CPT). 9W will probably suggest going a day later, have alternative routing available and be polite but forceful
3. can't help sorry
4. You didn't mention any onward on UA initially, is this still on one ticket? if so and delay is evident at HYD ask 9W to reroute to final destination, also look at alternate flights to SIN with 9W + SQ via DEL, MAA, CCU, BLR, etc and have those options available

Thanks for the reply! Sorry, I should have clarified, the entire itinerary is HYD-BOM-SIN-USA (on 9W, SQ, and UA, respectively), all on one ticket (yes, I'm going the long way).

So rebooking on a 9W flight to Europe or direct to US then onwards on UA or another *A carrier would also be an option. I think 9W flies to JFK?

A quick follow-up: I ended up arriving in BOM at 9:05PM at a bus gate, giving me plenty of time (2.5 hours) to make my connection. The bus dropped us off at the domestic arrivals area at ground level on the west side of T2, and from there the escalator takes you up to the fork in the road: if you have checked bags, turn left to enter domestic baggage claim, and if not, go straight, show the security guard your onward ticket (same deal as entering the check in hall from outside, and I'm happy to say that an email on my phone was accepted) and take a super long escalator that dumps you out at the western edge of the main check in hall. I don't think there was a shortcut from domestic arrivals to international departures like there is in Delhi T3 (in Delhi, there's a path to clear immigration as a transfer customer on the domestic arrivals level instead of going all the way out to check in), or at least I wasn't offered one, but it was convenient to not have to snake through baggage claim and go almost all the way outside just to get three floors up if I didn't have a checked bag to claim.

Once in the check-in hall, I followed the normal international departing passenger flow. SQ, LH, and LX seem to share a secluded business/first check in area A with a shortcut to business/first class security and immigration.

9W was unable to issue my SQ boarding pass in HYD (I asked at the check in desk, and the agent seemed to try, but he wasn't able to). I don't recall if my 9W PNR had my onward flights on it (they didn't make it particularly easy to check my PNR online given the ticket issued by UA).

Thanks again for the replies! I hope this helps future travelers, and I'm glad I don't have any tips on 9W's IRROPS handling to share this time around. There's always next time, though.

Quick question, is 1hr 40 min connection time ok IN BOM for INT to INT transfer (SIN-BOM-USA)? Google flights website shows SQ flight to BOM get's delayed often for 30+min. Will be in business class all the way with only carry on. Also have multiple entry visas for India just in case.

It really depends who you are connecting to. United will close their transfer desk an hour before departure...

Thanks Oliver, it's UA. What if it's on AC? What if I have already checked-in and have boarding pass on my phone?

No mobile boarding passes available ex India, you need to have a paper boarding pass issued by an ailrine or an online boarding pass validated by the operating airline. If you are transiting the validation is done at the transfer desk. I wouldn't do 1h40min on separate tickets.

Thanks again.

I am thinking about booking an award ticket into BOM with ET arriving at 7 am and then a separate revenue ticket to SIN with SQ departing BOM at 11pm on the same day. I understand there's an airside transit hotel, but my question is whether ET will check my bags all the way to SIN, despite being on separate tickets. If not, what is the price of the transit visa for US citizens? I am getting conflicting info on this. Thanks!

Unlikely that ET will check your bags through.

Here's the visa you need, fee is $75 - https://indianvisaonline.gov.in/evisa/tvoa.html and here's info on the transit hotel - Mumbai Airport Hotels ? Niranta Transit Hotel & Lounge

I'd recommend you book the landside hotel since you won't be able to check in and clear immigration until about 3-4 hours before your SQ flight.

Or contact Niranta and/or GVK Pranaam arrival services with your situation and ask if they can do something for you.