is this sentence correct???

[Unregistered]

Regarding the accident, he said he saw John only for an instant before the impact

[Raymott]

Regarding the accident, he said he saw John only for an instant before the impact.

Yes, it's correct.

[motico]

Yes, it's correct.

Assuming that the accident had taken place before he told about it shouldn't we use the past perfect? That is: Regarding the accident, he said he had seen John only for an instant before the impact

[Raymott]

Assuming that the accident had taken place before he told about it shouldn't we use the past perfect? That is: Regarding the accident, he said he had seen John only for an instant before the impact

There's no need for the past perfect. The adverb 'before' and the context clearly establish the timing. But you could use the past perfect here if you wanted to.

[motico]

There's no need for the past perfect. The adverb 'before' and the context clearly establish the timing. But you could use the past perfect here if you wanted to.

As a student at high school (although it was many years ago…) I learnt that particularly the appearance of adverbs like: before, previously, a year ago, etc. in the sentence, necessitates using the past perfect, as they indicate the occurrence of one action in the past before the other! (And I remember doing endless exercises practicing that…) And now you are 'shattering the myth' for me!

[Raymott]

As a student at high school (although it was many years ago…) I learnt that particularly the appearance of adverbs like: before, previously, a year ago, etc. in the sentence, necessitates using the past perfect, as they indicate the occurrence of one action in the past before the other! (And I remember doing endless exercises practicing that…) And now you are 'shattering the myth' for me!

Stick around and prepare to have some more of your grammatical illusions shattered.
High school grammar tends to include a lot of "always, never, must" etc., which are not really warranted in the real world of language. But it seems that such rules have allowed you to learn functional English, which I'm sure is the point of them.

[motico]

Thank you for warning me.
It is a pleasure to learn from you!