I am travelling soon from Los Angeles to Kolkata via Shanghai. Nanchong. Kunming by China Eastern all the way. I heard that checked baggage has to be taken out for customs & rechecked in at Shanghai. Is this true, or baggage can be checked through to Kolkata ( since it is one Airline & one itinerary) ? With only a short layover at Shanghai, it may be impossible to compkete checkout, customs and check-in there. Will really appreciate helpful tips from anyone who has travelled recently on this route ( basically connecting two domestic end-points in China ). Thanks.
China Eastern's website and my personal experience in China (though not with China Eastern or this route in particular) suggests that the information you received by the airline agent is incorrect. It seems that you will have to collect and re-check your baggage in both Shanghai and Kunming, but probably not in Nanchong.
For PVG, China Eastern has a transfer guide, though only in Chinese.
The second column of the guide (for international to domestic transfers) says the following:
国 际/ 及 港 澳 台 航 班
中 转 -> 国二内 航 班
您 乘 坐 的 航 班 抵 达 浦 东 国 际 机 场 T1 航 站 楼后 ，跟随国际到达长廊上方 “ 中转" (1) 样 灯 箱 指 引 ，来 到 长 廊 尽 头 处 。
跟 随 “ 转 国内” 标识 (6) 进入 旅客通 道 ， 办 理 入 境 手 续 。
下 楼 到 达 行李 提 取 处：
- 如 您 已持 有后 续航 班登 机 牌 ，请 进 入 左 侧的 中转厅 (7) ，如有托运行李的请先等 待 海 关 的 行 李 检 查 后 前 往 东 航 中转 服 务 柜 台确 认 后 续 登 机 牌 。 完 成 后 从 中 转 旅 客 出口(8) 离开中转厅 ，前往三层接受国 内 出发 安 检 后 ， 找 到 登 机 牌 上 指 示 的 登 机 口 候 机 。
- 如 您 未持 有 后 续 航 班 登 机 牌 ，请 先 提 取 行李（如 有），进 入左侧 的中转厅(7) ，接 受 行 李 安 检 及 海 关 的 检 验 后 ，前 往 东航 中 转 服 务 柜 台 办理 后续 航 班 登 机 牌 。 完 成后从 中转旅客 出口(8)离 开中转厅 ，前 往 三 层 接 受 国 内 出发 安 检 后 ， 找 到 登 机 牌 上 指 示 的 登 机 口候 机 。
I don't understand any Chinese, but Google Translate suggests that you have to collect your baggage and go through customs even if you already have a boarding pass for your next flight. (Maybe a Chinese speaker can confirm or correct this?) It would make sense to me, since Shanghai is your first port of entry to China and usually, this is where you have to present yourself and your baggage to Chinese customs. After doing so, you will be able to re-check your baggage at a dedicated transfer counter. Note that if you miss your connection at PVG, China Eastern typically has a couple of nonstop flights to Kunming later in the day, so you should easily be reaccommodated in order to be able to catch your flight to Kolkata.
At Nanchong, I would not expect you to have to collect your baggage, since the flights from PVG to NAO and NAO to KMG are operated under one flight number (MU5437, right?) and by the same aircraft and the layover in NAO is quite short. Maybe you won't even have to leave the aircraft in Nanchong.
Transit passengers with checked baggage can go to the baggage pick-up carousel on the 10th floor of B1 or the baggage carousel on the 6th floor of the B1 to handle the transit procedures.
Kind reminder: Kunming Airport transfer counter is available from 08: 30-22: 30.
On May 1st, Kunming Changshui Airport opened the "through flight" service, with five international connecting stations: Paris, Dubai, Bangkok, Singapore, Hong Kong; 15 domestic connecting stations: Beijing, Shanghai, Guangzhou, Xi'an, Hangzhou, Chengdu, Shenzhen, Changsha, Zhengzhou, Wuhan, Harbin, Nanning, Lanzhou, Lijiang, Banna.
After the through-trip service is opened, the international passengers to domestic / domestic to international passengers can apply for a joint boarding pass at the departure station, and the baggage will be directly connected to the destination; however, when passengers transit in Kunming, they need to cooperate with the luggage clearance Before heading to the boarding gate.
Unfortunately, Kolkata is not among the international destinations which benefit from this through-trip service, so you will have to collect and re-check your baggage once again.