Learn Hardcore Turkish: Tahliye sırasında sakin kalınmalı. - One must stay calm during the evacuation.

sıra (“turn/sequence,” here extended to “time/period”)
-sı (3rd person singular possessive: “its period”)
-nda (locative case: “in/at”) Combined sıra-sı-nda gives “in the time of,” i.e. during.

Why is sakin placed before kalınmalı, and what part of speech is it?

sakin is an adjective meaning calm. In this sentence it’s used adverbially to modify kalınmalı (“must stay/remain”). Turkish often lets adjectives function like adverbs without any extra ending.

What does the suffix -malı express in kalınmalı?

The -malı/-meli suffix indicates necessity or obligation—“must,” “should,” or “ought to.” So kalınmalı means “one must stay/remain.”

Why is there an -ın between kal and -malı in kalınmalı?

The -ın is the passive voice marker. Structurally:

kal (stem “stay”)
-ın (passive: “be stayed”)
-malı (necessity: “must be”) This yields an impersonal instruction: “one must stay.”

Why doesn’t the sentence include a subject like sen or siz?

Turkish often omits explicit personal pronouns when:

The subject is generic or impersonal.
The verb form (here passive + necessity) already makes clear it’s a general instruction (“one must…”).

Could you rephrase it to address you (plural) directly?

Yes. For “you all must remain calm during the evacuation,” say: (Siz) tahliye sırasında sakin kalmalısınız.

What’s the difference between tahliye sırasında and tahliye esnasında?

Both mean “during the evacuation.”

sırasında is neutral/colloquial.
esnasında is slightly more formal or literary but interchangeable here.

Can I use boyunca instead of sırasında?

Absolutely.
Tahliye boyunca sakin kalınmalı means “Calm must be maintained throughout the evacuation.”
boyunca (“throughout”) stresses the entire duration rather than a point in time, but the instruction remains the same.