September 11

Exemption from obligatory prayer is granted to those who find themselves in such a condition of insecurity that the saying of the Obligatory Prayers is not possible. The exemption applies whether one is travelling or at home, and it provides a means whereby Obligatory Prayers which have remained unsaid on account of these insecure circumstances may be compensated for.

Bahá’u’lláh has made it clear that obligatory prayer “is not suspended during travel” so long as one can find a “safe spot” in which to perform it (Q and A 58). 
- The Universal House of Justice  (The ‘Notes’ section of ‘The Kitab-i-Aqdas’)

From Baha’u’llah:
When travelling, if ye should stop and rest in some safe spot, perform ye—men and women alike—a single prostration in place of each unsaid Obligatory Prayer, and while prostrating say “Glorified be God, the Lord of Might and Majesty, of Grace and Bounty”. Whoso is unable to do this, let him say only “Glorified be God”; this shall assuredly suffice him. He is, of a truth, the all-sufficing, the ever-abiding, the forgiving, compassionate God. Upon completing your prostrations, seat yourselves cross-legged—men and women alike—and eighteen times repeat “Glorified be God, the Lord of the kingdoms of earth and heaven”. Thus doth the Lord make plain the ways of truth and guidance, ways that lead to one way, which is this Straight Path. Render thanks unto God for this most gracious favour; offer praise unto Him for this bounty that hath encompassed the heavens and the earth; extol Him for this mercy that hath pervaded all creation. 
- Baha’u’llah  (‘The Kitab-i-Aqdas’)