On Monday, I am going to take a flight. I would imagine I should say the Shehecheyanu when I land, thanking God for my continued existence, but is there a blessing I could or should say when I take off, asking God for safety?
Most say the traditional Prayer for Travel.
(From the Chabad site):
May it be Your will, G-d, our G-d and the G-d of our fathers, that You should lead us in peace and direct our steps in peace, and guide us in peace, and support us in peace, and cause us to reach our destination in life, joy, and peace (If one intends to return immediately, one adds: and return us in peace). Save us from every enemy and ambush, from robbers and wild beasts on the trip, and from all kinds of punishments that rage and come to the world. May You confer blessing upon the work of our hands and grant me grace, kindness, and mercy in Your eyes and in the eyes of all who see us, and bestow upon us abundant kindness and hearken to the voice of our prayer, for You hear the prayers of all. Blessed are You G-d, who hearkens to prayer.
You can still find some old prayer books that have a specially-composed prayer for air travel, but most people today just use the standard prayer for travel.