Tefilas Haderech is recited once you have left the city and entered an unsettled area — specifically, when there is a continuous gap of one parsah (approx. 3.84–4.61 km) with no chain of houses. It should ideally be said while in motion, shortly after departing the settled area.

When the route clearly qualifies, recite with the full closing bracha — "בָּרוּךְ אַתָּה יְיָ שׁוֹמֵעַ תְּפִלָּה." When uncertain (borderline distance, unclear road type), some poskim hold to recite the prayer without the closing bracha. Consult your Rav.

In Nusach Chabad, if one intends to return immediately (before the next morning), one inserts "וְתַחֲזִירֵנוּ לְשָׁלוֹם" (and return us in peace) into the tefillah. This way, the prayer covers both directions and need not be repeated on the return.

The overwhelming consensus of contemporary poskim — including Rav Moshe Feinstein zt"l and Rav Ovadia Yosef zt"l — is that Tefilas Haderech is recited with a bracha when flying. The preferred time is after takeoff once the plane is airborne.

If you forgot and are still traveling through an unsettled area, recite the prayer without the closing bracha. Once you have arrived at your destination or re-entered a populated area, the time has passed and it should not be recited.

Tefilas Haderech with Hashem's name in the closing bracha is recited the first day of travel. On subsequent days, it is said after davening without mentioning Hashem's name in the closing bracha. Ask your Rav for your specific situation.

One person may recite the bracha aloud and the group answers Amein, provided they are listening with intent (kavana). The text here uses plural forms. When traveling alone, use singular: תוֹלִיכֵנִי, תַּצְעִידֵנִי, תַּגִּיעֵנִי, etc.