I was airborne at that time one night, twixt Singapore and Calcutta, somewhere near Phuket. (one pronounced that VERY carefully )
We were told to avoid Dacca, and navigate to a point in the ocean due South of Calcutta and then establish inbound on the 180 radial of Calcutta VOR.
Out came the sextant, and having reached the required position I handed navigation decisions back to the pilots, to maintain the 180 radial as instructed. Except ....... they couldn't receive the VOR signal, so called Calcutta ATC, who said - "we have switched off all navigation aids, maintain the 180 radial of the Calcutta VOR inbound !"
We called Company in Dum Dum, and they told us that ATC had switched off the VOR and NDB, and turned off all airport lights, including the navigation identity beacon, and the runway approach lights, but when we were established on finals they would switch on the runway lights for 30 seconds to "assist" our landing. We asked the current weather - 800 ft overcast in rain, we were told. We diverted to Rangoon, and told to reverse our track and maintain the 180 radial of the VOR back to the same oceanic position,with the VOR switched off.
INS ? GPS ? don't make me laugh.
Indian airspace was indeed closed, and all aircraft were ordered to land at Calcutta or Bombay for clearance before continuing across the Country, we were bound for Calcutta so that was OK but a following KLM aircraft advised he was bound for Bombay, so would continue - we never heard from him again, tho' to be fair we didn't hear of any KLM aircraft being shot down by a musket, either.