This poet is from Israel herself, and she brought a book of haiku translated into Hebrew to share at her first meeting with the Haiku Northwest group. What follows is my response to the author. As possible revisions emerge, I hope the evolution of this poem—at least from my eyes—is helpful for others to see, especially those who are new to haiku. In the process, I offer ways to compress the poem, clarify the seasonal reference, and refine the poem to have a helpful (if not requisite) two-part structure. I also encourage returning to the seed of the poem—the original experience, or “triggering town,” as Richard Hugo called it—and the empathy that the poet hints at by trying to capture a riveting moment even though she wasn’t there. Any given haiku experience can go in as many directions as there are poets. What follows turns out to be one possibility, and it is offered in the same spirit as the Japanese tradition of tensaku (ten = additions; saku = subtractions), the process whereby haiku are revised by teachers or editors for their students.

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Regarding your poem, the English isn’t quite natural. It has a problem with what Paul O. Williams has called “tontoism,” or missing the use of natural articles (the, a, an). So the first fix I’d make is as follows, adding “the” twice:

                summer heat
                soaring birds above the canyon
                the last sound before her fall

I would next suggest that having more than one bird isn’t necessary or helpful in the poem, so it would sharpen the poem’s focus to have just one bird:

                summer heat
                a soaring bird above the canyon
                the last sound before her fall

It might improve the emphasis and rhythm of the middle line to reorder some of the words:

                summer heat
                a bird soaring above the canyon
                the last sound before her fall

I also wonder if it might improve the poem to name the bird. You have many options, but here’s one possibility:

                summer heat
                a falcon soaring above the canyon
                the last sound before her fall

You could choose a bird that carries appropriate overtones or mythological associations that fit your friend. An eagle, osprey, crow, who knows. Or something in contrast, such as a buzzard or vulture, although that might raise the wrong overtones. Or perhaps other specific birds live in the canyon where this happened that would be appropriate to name.
        Also, if it were up to me, I’d emphasize the cut after the first line by adding an ellipsis. Here I think an ellipsis works better than a dash to suggest the slow languorousness of the heat (a dash is too quick), and perhaps to heighten the context:

                summer heat . . .
                a falcon soaring above the canyon
                the last sound before her fall

Meanwhile, the poem still has three parts (each line is a distinct and grammatically separate unit), and haiku usually avoid having three parts. It is better to have two parts so there’s some clear tension or reverberation between just those two parts. Having three parts diffuses the poem too much. This is perhaps the hardest thing to fix so far (to get the right tone in the relationship between the two parts), but here’s a crude attempt to get it started:

                summer heat . . .
                a falcon soaring above the canyon
                is the last sound before her fall

All I’ve done is to add the connecting word “is” to make the last two lines read as one uncut grammatical unit. But of course, even without that addition, the last two lines were already too long. It occurs to me that “heat” already tells me it’s summer, so you don’t need “summer,” and “canyon” could easily be combined with “heat”:

                canyon heat . . .
                a falcon soaring
                is the last sound before her fall

Now it’s odd to say that something “soaring” is the last sound heard, so we should flip that phrase to say “a soaring falcon” so that the word “sound” is more clearly related to the falcon rather than the fact that it was soaring:

                canyon heat . . .
                a soaring falcon
                is the last sound before her fall

Actually, it probably doesn’t matter that the bird is soaring (or that could be implied). What really matters, because of your mention of “sound,” is not really the soaring at all but just the bird as the sound’s source. So I’d lose “soaring” entirely. It’s not really the essence of the poem, I’d say. Also, the last line is still too long, “is” is the weakest possible verb, and “sound” is a relatively flat word, too. So, here’s how I might further revise the poem with a lot more compression:

                canyon heat . . .
                a falcon’s cry
                before she falls

The last line could also be “before her fall” or “before the fall.” But now a new problem emerges, and that’s the ambiguity of who (or what) “she” is—or “her.” This problem was present in your own most recent version, but it becomes more starkly apparent in my revision. Who is “she”? It could even be misunderstood as the falcon, and if readers think it’s the falcon, then the “fall” would be the falcon’s intentional dive, and such an image would be a good thing rather than a bad thing, which takes the poem in the wrong direction, away from the tragedy of your friend’s fatal fall. Here’s an obvious way to prevent such a misreading:

                canyon heat . . .
                a falcon’s cry
                before my friend falls

Would that work for you? Or maybe it says too much, too bluntly. This is where, for me, a revision gets really hard, because it might be too easy to get away from your intent, especially with such a sensitive and personal subject. But in such situations, I would try to go back to the original experience. Maybe we could change the word “fall” to “slip” and maybe we could add the word “foot”:

                canyon heat . . .
                a falcon’s cry
                before her foot slips

This becomes a little more visual and concrete, too, because it talks about a specific and precise action rather than a more general “fall.” So I think the poem is getting stronger. However, maybe we should switch the order of the lines so that “her” might be more clearly implied as a person before the poem introduces the falcon:

                canyon heat . . .
                her foot slips
                at the falcon’s cry

I think this is a point at which I’d be happy with the poem. However, there’s one more option that would give it personal richness and colour, and that would be to name the place where this really happened (in Japanese haiku, the technique of relying on the overtones of famous place names or other allusions is known as utamakura, literally “poem pillow,” as if the location or allusion is a “pillow” where your poem rests). You refer to Mezada. I believe most people know it as Masada, and I think you could say that and be widely understood—and the poem would gain many rich associations with the location, especially with the tragic story of mass suicide for which Masada is famous. Here’s how I would revise the poem:

                Masada heat . . .
                her foot slips
                at the falcon’s cry

Now the poem is much stronger, I’d say. The setting of Masada may require you to suggest a different bird—I don’t know what bird would be the most appropriate, or would falcon still work? Perhaps you could review a list of Israeli birds for ideas? A kestrel, maybe? Or a shrike?

                Masada heat . . .
                her foot slips
                at the kestrel’s cry

                Masada heat . . .
                her foot slips
                at the shrike’s cry

Both versions have their virtues. The phrase “kestrel’s cry” has nice alliteration, but “shrike’s cry” also implies the word “shriek,” which to me helps make it slightly stronger than “kestrel,” at least to fit the experience that inspired your haiku. In this poem, with its very personal and poignant subject matter, I don’t think you want to introduce the poetic “beauty” of alliteration (in “kestrel’s cry”), or distract with that cleverness, even if minimal. Consequently, I think “shrike’s cry” is best, if you decide not to stick with “falcon.”
        Whatever bird you choose, the word “Masada” has full overtones for many people. The subtlety and understatement of a slipping foot is much stronger than referring to a fall. We know it’s summer from the heat, and the setting of Masada tells us that it’s a desert heat too, and brings to mind all sorts of Biblical and historic associations. The slipping foot creates just a little ambiguity as to whether this might have been an accident or deliberate, and that mystery is wisely not explained in the poem, which is something that helps keep the reader engaged. You may not like the possible suggestion that this tragedy was deliberate rather than an accident (even though you’ve told me that it was an accident), but for the poem’s sake I believe this slight ambiguity is helpful. A slipping foot suggests an accident more than a deliberate act, I would say, but it doesn’t hurt to have the merest suggestion of suicide—and I do believe it is very slight, if at all. To the extent that such an ambiguity exists, the poem may be further energized by this mystery or tension. In fact, the context of Masada is really what suggests that suicide might have been what happened, but what the poem actually says is that her foot slipped—an accident. That’s all we need to know, regardless of what the full truth is. And that’s the beauty of haiku—we don’t need to know the full truth. The poem dwells just in this one fragmentary moment, and lets us imagine what went on before and after. We get to complete the poem by our empathic entry into the image-moment that you have sculpted. We can dwell in its mystery. It’s a rich moment, and I think it works quite nicely. I think you’ve got a fine poem here.
        And yes, this is still all your haiku—all of it came out of your original poem, from the seed of your empathetic experience and what you told me about the story, so I hope you will consider this poem to be fully yours (doing so would be in the Japanese tradition of tensaku, where any revisions offered to your poem, even if extensive, still remain fully yours as the original author). I trust that my suggestions still remain true to the experience, and serve to memorialize your friend appropriately. And like so many haiku in our lives, I hope the poem might give you consolation and some measure of healing.

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For a few readers, perhaps this poem raises other questions. For example, is it morally or aesthetically appropriate to write about someone else’s experience? Can we write effectively about something that we didn’t personally experience? Bashō heavily revised the poems and the sequence of some events in the Oku no Hosomichi—and even went as far as changing author attributions in renga collaborations (he thought it would be better for some poems if a different person was listed as the author). And I recall Buson’s famous poem about stepping on his dead wife’s comb in their bedroom, and how feeling the comb under his heel chilled him deeply. Buson, of course, was taking poetic license, because his wife was very much alive at the time. What matters, it seems to me, is whether the poem itself feels authentic, and affects us, as readers, in authentic ways—if the poem speaks poetic truth. We can never be certain that something really did or didn’t happen anyway, so all we can judge is the poem itself—and its emotional effect on us as readers. Curtis Dunlap once wrote about this matter, referring to what he calls “empathy haiku.” He defines this approach as walking in someone else’s shoes and writing haiku “from events in someone else’s life” (Modern Haiku 40:2, Summer 2009, page 137). In this poet’s case, I applaud her expression of empathy, for entering into that gut-wrenching moment as a means to remember and honour her friend, as painful as that moment obviously was. By doing so, she is able to capture and share her own emotion, and perhaps all of us can find healing through her brave poetic act in the face of her friend’s tragedy.

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Addendum: Shortly after my email to this poet, she wrote to say that she liked the reference to Masada, and said that the most fitting bird would be a falcon. So here is the final version of the poem she preferred:

                Masada heat . . .
                her foot slips
                at the falcon’s cry