From my personal experience...

I recently had a flight from PVG (Shanghai) - BOM , the flight was via Delhi, no change of planes. We sit and wait for the passengers from Delhi to Mumbai. Now these passengers are 100% domestic. which means this is 100% domestic leg for them. (no customs or immigration after arrival at BOM). Now my question is that with these rules isn't it very easy for some one traveling from China to India to escape the customs ? I mean there might already be things like this been happening ? It is not (at all) difficult to make some one book DEL - BOM same flight as yours.

Just came to my mind and it seems like a serious flaw.

Experts please throw some light on this. I just pray nothing bad ever comes inside our country ever !

if you are talking about the air india flight, the domestic passengers will have a big D on their boarding pass. the plane arrives at T2 BOM, and these pax have to pass through immigration queue, where the immigration guy will let them go through a special line for the guys with domestic boarding passes. people with intl. boarding passes will have to go thru immigration. At customs again, the D is the differentiator.

No, you did not get me.

I know there is a separate queue for the domestic passengers.

I mean to say , what if the domestic guy who is traveling DEL-BOM is already friends with someone who is traveling PVG-BOM and they exchange their bags because the guy from china has something in his bag which he should not have. Are the guys with a big D on their boarding pass also liable to go through the customs scanner (even if random).

Yep, that may be an issue.

Then this is pretty serious considering the risks involved. The only solution I feel which can be done instantly is check all the baggage getting down from a flight consisting any international passenger. But long term solution should be to not let any domestic passenger be seated on an international flight.

This co-mingling has been going on since ages, I've been on such a flight back already in 1987 and 1994... if people were exchanging kgs of gold in flight it would have been a major problem and resolved ages ago. You do have to sign a declaration for customs what you have on you when you walk thru immigration as a domestic passenger.

If I remember correctly, luggage for all passengers is screened. You do have a separate passage to by pass immigration, but not for luggage screening. But I may be wrong here since it's been some time.

i've taken a few of these flights between del-bom....never have my bags been screened as a domestic passenger....

Same here. When I arrived in CCU on a 'domestic/international' AI flight last year the customs officer got wet eyes seeing me with coming towards her with my clearly international luggage. However as I came closer she noticed the domestic luggage tags (I had to recheck in DEL as I was on separate tickets) and was very disappointed and just waved me thru.

Nopes, never, they just pass through.

My question is, if it is happening since many years, I am very sure things must be happening like this and it is weird if nothing else.

I did a DEL-MAA like this a few months ago. MAA had everyone, including domestic pax, hand luggage scanned by x-ray.

She must have been waiting for schnitzel and potato salad.

Yes but you still can not deny a domestic passenger taking prohibited items (internationally). Unless there is a way to stop the inflight exchange of "stuff" there is no way this should be allowed and I still treat it as a serious flaw.

You don't even need to exchange anything.

What would stop someone motivated enough from just buying two separate tickets (e.g. one for PVG-BOM, another for DEL-BOM, and check in online for both). Then upon arrival, even though the itinerary flown was actually PVG-BOM, the person would present their DEL-BOM boarding pass (with a large D printed on it) at customs. And it's a completely valid boarding pass, as I highly doubt that there's any real time information exchange system in place that would inform customs upon scanning the BP that the flight wasn't actually taken.

Yes this is a BIG security hole. I noticed it years ago. There are many ways that international passengers can bring contraband without having to go through immigration and customs. Heck even human trafficking can take place this way. It's amazing that no one thought this out fully.

Most of the time they don't even read your BP at the destination. Just quickly show them the "D" mark and walk out. It doesn't even have to be in your name.

One of these news channels in India should do an investigative piece where they send people who exchange BPs etc. That may be the only way to get this hole closed.

The domestic boarding pass comes with its own procedures. if someone is coming from PVG, how will they show a CISF stamp which would be imposed only when they were flying domestic