Learn Hardcore Turkish: Rezervasyon yaptıracaktım, tam ararken telefonum kapandı. - I was going to make a reservation; just as I was calling, my phone died.

It’s the future-in-the-past. Form: -AcAK (future) + idi (past of to be) = -acaktı(m). So yaptıracaktım means I was going to have (something) done / I intended to have (something) done / I was about to have (something) done. In context, it usually implies the plan didn’t happen, often because of what follows.

Form breakdown: yap-tır-a-cak-tı-m (do-causative-future-past-1sg).

Why is it yaptırmak and not yapmak with rezervasyon?

Because rezervasyon yaptırmak is the idiomatic way to say you make a reservation with a place (you have them enter it in their system). It uses the causative -tIr: you’re effectively “having a reservation made” for you. You’ll also hear rezervasyon yapmak, especially for online bookings you do yourself, but yaptırmak is very common and natural when dealing with a venue by phone.

Can I say Rezervasyon yapacaktım instead?

Yes. Rezervasyon yapacaktım is understood and common, especially if you’re making it yourself (e.g., online). With a phone call to a restaurant, yaptıracaktım often sounds a bit more idiomatic, but both are fine.

Does yaptıracaktım also work as a polite way to say what I want to do now?

Yes. In service contexts, people soften requests with future-in-the-past: Bir rezervasyon yaptıracaktım = I’d like to make a reservation. It’s polite and indirect, not literally about the past in that usage.

What does tam add in tam ararken?

tam intensifies timing: just / exactly / right when. So tam ararken means right as I was calling. Without tam, ararken is simply while calling.

How is ararken formed, and what does it mean?

It means while calling. It’s built from the aorist plus -ken:

ara- (call) + aorist -r → arar
arar + ken → ararken (while calling)

This -ken forms an adverbial time clause: “while/when doing.” Compare gelirken (while coming), okurken (while reading).

What’s the difference between ararken and arıyorken?

Both can mean while calling.

ararken (aorist + -ken) is the default, general “while doing X.”
arıyorken (present progressive -yor
- -ken) emphasizes the ongoing nature at that very moment. It’s also common.
  Either is acceptable here: tam ararken or tam arıyorken.

What about arayacakken?

arayacakken is -ecek + -ken: when (I was) about to call.

tam arayacakken = right when I was about to call (before actually starting).
Your sentence uses ararken (during the act), but tam arayacakken would also fit well if you mean “on the verge of calling.”

Why is it telefonum kapandı and not telefonumu kapattım?

telefonum kapandı uses intransitive kapanmak = my phone turned off (by itself, e.g., battery died).
telefonumu kapattım uses transitive kapatmak = I turned my phone off (I did it).

What does the -um in telefonum show?

It’s the 1st person singular possessive: my phone.
Note the contrasts:

telefonum kapandı = my phone turned off.
telefonu kapandı = his/her phone turned off (3rd person possessive).
telefonu kapattım = I turned off the phone (accusative object of a transitive verb).

Could this sentence mean the call dropped, not that the phone turned off?

No. kapandı for a phone means it turned off. For a dropped call, you’d say things like:

Hat kesildi / görüşme kesildi = the line/call cut off
Bağlantı koptu = the connection dropped

Is the subject “I” understood in ararken?

Yes. In -ken clauses, the subject is typically understood from context. Here it’s I (the person who intended to make the reservation). If you want to be explicit, you can say Ben ararken telefonum kapandı.

Is the comma necessary, and can I change the word order?

The comma just separates the two clauses for readability. You can reorder:

Rezervasyon yaptıracaktım. Tam ararken telefonum kapandı.
Tam ararken telefonum kapandı, rezervasyon yaptıracaktım. (less common but possible) If you want to make the causal link explicit, add o yüzden or ama:
Tam ararken telefonum kapandı, o yüzden rezervasyon yaptıramadım.

How would I negate or ask a question with this tense?

Negative: Rezervasyon yaptırmayacaktım = I wasn’t going to make a reservation.
Form: yap-tır-ma-yacak-tı-m.
Question: Rezervasyon yaptıracak mıydım? = Was I going to make a reservation?
The question particle mi is separate and takes vowel harmony.