CNN Week 7

In "How Phones Work in Flight" talks about the lack of phone calls, texts or social media postings from missing Malaysia Airlines Flight 370 which raised a number of questions about how cell phones work on airplanes. Despite the urgings of flight crews to turn off all phones or put them in airplane mode, cell phones can continue to work after a plane takes off, but only while in range of a cellular tower.

Cell phones communicate through cell towers, which are located on the ground but can stretch hundreds of feet into the air. As an airplane rises, it gets further from these towers and eventually moves out of contact range. For efficiency, many towers are designed to direct their signal where its most useful: on the ground, not into the sky above.