Cell Phones And Planes

Please turn off all personal electronic devices, including laptops and cell phones for the duration of this flight. Thank You.

This is an announcement you can unmistakingly recognize if you have ever travelled by an airplane. But do you know why airliners lay so much emphasis on this?

Theoretically, active radio transmitters such as mobile phones, walkie–talkies, portable computers or gaming devices may interfere with the aircraft’s navigation and operation systems.

But what if there’s an emergency and you have to make a phone call? Such cases have occured and we’re going to compare two of the most infamous of these cases :

The September 11 attacks (also referred to as 9/11) were a series of four coordinated terrorist attacks by the terrorist group Al-Qaeda against the United States on the morning of Tuesday, September 11, 2001. Four passenger planes operated by two major U.S. passenger air carriers (United Airlines and American Airlines) were hijacked by 19 Al-Qaeda terrorists.

One of these planes was United Airlines Flight 93 (UA93) which crashed somewhere in Pennsylvania. Using cell-phones and airfones, passengers on the plane reached out to loved ones, sought help and warned them about the ongoing terrorist attack. Flight 93's cockpit voice recorder revealed crew and passengers tried to seize control of the plane from the hijackers after learning through phone calls that other three flights had been crashed into buildings. Once it became evident that the passengers might gain control, the hijackers rolled the plane and intentionally crashed it.

In comparison, the Malaysian Airlines Flight 370 (MH370) which went missing on 8th March 2014, maintained absolute radio silence. No texts, no calls, no tweets. It was flying from Kuala Lumpur International Airport to its destination, Beijing Capital International Airport. The disappearance of MH370 has been dubbed one of the greatest aviation mysteries of all time.

The lack of phone calls, texts or social media postings from missing Malaysia Airlines Flight 370 has raised a number of questions about how cell phones work on airplanes. Let’s find out.

1. Altitude :Despite the continuous reminders by flight crews to turn off passenger cell phones or put them in airplane mode, cell phones continue to work in flight, but only while in range of a cellular tower. As an airplane rises, it moves further out of the range of these cellular towers. The flight MH370 was cruising at an altitude of 35,000 feet which is well out of the range of these towers. Passengers on-board the UA93 were able to make phone calls because the plane was flying very low in densely populated areas with an abundance of cell towers.

2. Speed : Speed can also make maintaining a cellular connection difficult, as a device has to switch from tower to tower to maintain a connection. Telecom researchers say that a flight will have to be going 155 miles per hour (250 kilometers per hour) or less for phones in cell-tower range to make or receive calls.

These two factors could contribute to understanding why no phone calls were made by passengers. However, this doesn’t end here. Researchers believe that there are many other factors that could have influenced such radio silence. They haven’t ruled out anything yet.