How much notice do you have to give? http://www.afceco.org/buy-celebrex-in-canada celebrex 100mg  Passengers are now required to turn off phones and other electronic devices while planes are below 10,000 feet to prevent interference with sensitive cockpit equipment. Takeoffs and landings are the most critical phases of flight. But newer aircraft are better equipped to prevent electronic interference, and critics long have complained that the safety concerns behind the regulations are groundless.