I am having some confusion in learning Past Perfect continuous tense.
In my reading I come across some rules while constructing Past Perfect continuous tense. Which also differentiate this tense from Simple Past continues tense.
The Time / Duration
Past Perfect continuous indicates the activity which started in Past and end in the past or interrupted by some other action. And it has not implication in present.
E.g. I had been talking on mobile over an hour before Tony arrived. (Past Perfect Continues)
But Sometimes Time/Duration is not mentioned in the sentence construction which creates confusion in both tenses.
E.g. 1) I had been talking on phone before Tony arrived. 2) He had been in tension. 3) He had been writing the Letter. 4) That Plane had been descending. (See my below example for detail) 5) That Car had been approaching me.
My Question is that how and when exactly should I use past continuous tense in English if my understanding is wrong? As per my understanding Time duration should mention while constructing Past Perfect continues tense.
One more Question.
On May 6, a serious incident took place when an IndiGo Mumbai Jaipur flight, which was to take off from Mumbai airport’s runway 14, delayed its departure because of which a Jet Airways aircraft that had been descending and cleared to land on the same runway was forced to do a go-around at the last moment.
If I use was instead of had been will it change the scenario?
I.e. had been descending and was descending.
Thanks for reading my question please emplain in detail.