I don't quite understand what you mean by "there is nothing here to indicate that the time period earlier in the
summer was either before or after the flight delay."
Do you mean that the reader would expect you, the writer, to continue with the
sentence? Yet, by leaving it with "had been delayed," it's as if you'd cut the sentence off, right? The reader
expects information regarding whether or not the
"time period earlier in the
summer was either before or after the flight delay" in the words that follow, but you neglect to show this.
The use of past perfect almost always requires that a past point of view be established first.
Could you clarify this a bit more? A past point of view had already been established at the sentence's beginning: "my most recent example was EARLIER THIS SUMMER..." so we know that described events that follow will be in the past. I sort of understand, and I sort of don't.
How about other sentences?
If you had been listening, you would know.
If you were listening, you would know.
OR
While everyone had been sleeping, I was working.
While everyone was sleeping, I was working.
I suppose the second sentence would be correct? Because the act of sleeping had not been complete while the speaker worked. (even in this sentence, I don't know whether or not I should use "Because the act of sleeping HAD NOT BEEN complete while the speaker worked," or "Because the act of sleeping WAS NOT COMPLETE while the speaker worked.") Do you understand my frustration!? I feel like I can never get to the bottom of this!! There are just so many ways this past-perfect/past-simple stuff can pop up, and I very desperately want a definitive answer to all of this. I highly, HIGHLY doubt that other native speakers go through this sort of deep analysis for every sentence they use that MAY require the use of a past-perfect tense. I do understand how it works, and I usually just say whatever sounds "right," but I can't really explain why I think it's right.
Thanks for the replies, though! =(