New post on cell phones on planes

_posts/2024/2024-06-10-why-cellphones-cannot-be-used-on-planes.md

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+---
+id: why-cellphones-cannot-be-used-on-planes
+title: Why Cellphones Cannot Be Used on Planes
+date: 2024-06-10
+author: k3jph
+layout: post
+permalink: /2024/06/10/why-cellphones-cannot-be-used-on-planes
+featured_image: /assets/img/2024/why-cellphones-cannot-be-used-on-planes.webp
+categories:
+- Blog 
+tags:
+- public policy
+- electrical engineering
+---
+
+Cell phones are an essential part of our everyday lives, but when
+it comes to air travel, passengers are often reminded to turn off
+their devices or switch them to airplane mode. Contrary to popular
+belief, the real reason behind these restrictions has little to do
+with interfering with the aircraft's systems. Instead, the main
+concern historically involved network overload issues with old
+analog cell phones. Modern digital phones have largely mitigated
+these issues, but regulatory reasons still justify many of the
+current restrictions. Additionally, these restrictions are primarily
+enforced by the FCC, not the FAA, and apply to all flying machines,
+including gliders, hot air balloons, even [free-falling
+skydivers](http://www.cnn.com/2011/TECH/mobile/07/18/iphone.skydive/index.html).
+In this blog post, we will unravel the true reasons behind the cell
+phone regulations on airplanes, exploring the technological and
+regulatory factors at play.
+
+## Constant Bombardment with Cellular Signals
+
+Airplanes flying at typical cruising altitudes are constantly
+bombarded with cellular signals from ground-based cell towers.
+Understanding the range of cellular devices and towers, along with
+the altitude at which aircraft operate, helps explain why these
+signals remain a concern.
+
+1. **Range of a Cellular Device:**
+   - **Typical Range:** A cell phone typically has a transmission
+   range of 1-2 kilometers in urban areas, extending up to 10-15
+   kilometers in rural areas under ideal conditions.  - **Ideal
+   Conditions:** With line-of-sight and no obstructions, a cell
+   phone can potentially transmit up to 30-50 kilometers (18-31
+   miles).
+
+2. **Range of a Cellular Tower:**
+   - **Typical Range:** Cell towers have a range of 1-2 kilometers
+   in urban areas, extending up to 30-50 kilometers (18-31 miles)
+   in rural areas.  - **Ideal Conditions:** Under perfect line-of-sight
+   conditions, cell towers can potentially transmit up to 70-100
+   kilometers (43-62 miles).
+
+3. **Height of Aircraft Flying:**
+   - **Typical Altitude:** [Civilian airliners typically cruise at
+   altitudes between 30,000 and 40,000 feet (approximately 9,144
+   to 12,192 meters or 9 to 12
+   kilometers)](https://www.travelandleisure.com/why-do-airplanes-fly-at-35000-feet-8637909).
+   - **Maximum Altitude:** The maximum cruising altitude for most
+   civilian airliners is around 42,000 feet (approximately 12,802
+   meters or 12.8 kilometers).
+
+Given these ranges, it is evident that aircraft at cruising altitudes
+fly well within the practical transmission limits of both cellular
+devices and cell towers. While the maximum range of cellular devices
+and towers are theoretical, aircraft remain in range to receive
+these signals due to their altitude.
+
+Additionally, while cell towers use directional antennas aimed at
+the surrounding terrain to optimize coverage and minimize interference,
+cell phones are inherently omnidirectional. This means that a cell
+phone signal spreads out in all directions, increasing the likelihood
+of connecting with multiple cell towers simultaneously, particularly
+at high altitudes where the line-of-sight to multiple towers is
+unobstructed.
+
+## The Evolution of Regulations
+
+Early regulations were based on concerns that analog cell phones
+could interfere with cellular networks by simultaneously communicating
+with multiple ground towers at high speeds and altitudes. This
+created technical challenges for cellular providers, leading to the
+Federal Communications Commission (FCC) enacting rules to prevent
+such issues.
+
+## Actual Concerns with Analog Phones
+
+{% include figure.html width="4" placement="right"
+   image="/2024/why-cellphones-cannot-be-used-on-planes/zack-morris-phone.webp"
+   alt="Zack Morris and his phone" cap="Zack Morris and his phone"
+   %}
+
+[Analog cell phones](http://osmocom-analog.eversberg.eu/docs/amps.html),
+such as the old-style bag phones or the famous "Zack Morris phone,"
+operated on a different technology compared to modern digital phones.
+Analog phones used frequency modulation (FM) to transmit voice
+signals. Each call was assigned a specific frequency within a band,
+and the phone maintained that frequency for the duration of the
+call. Here are the key aspects that caused issues:
+
+1. **Continuous Signal Transmission:**
+   Analog phones transmitted a continuous signal that did not switch
+   frequencies dynamically. This meant that as a plane moved through
+   the air, the phone would attempt to communicate with multiple
+   cell towers simultaneously, often without releasing the previous
+   connection. This continuous signal transmission could overload
+   the cellular network on the ground, as multiple towers tried to
+   handle the same call.
+
+2. **Limited Handoff Capability:**
+   Unlike modern digital phones, which can seamlessly hand off calls
+   between towers (a process known as "handoff"), analog phones had
+   limited capability to manage these transitions smoothly. The
+   handoff process in analog systems was less efficient, leading
+   to dropped calls or multiple towers attempting to handle the
+   same call. This inefficiency could lead to significant strain
+   on the network, especially in densely populated areas with many
+   cell towers.
+
+3. **Signal Interference:**
+   The analog signal was more prone to interference and degradation
+   over long distances. As an aircraft travels at high altitudes
+   and speeds, the analog signal could degrade, causing poor call
+   quality and increased attempts by the phone to reconnect, further
+   straining the network.
+
+4. **Broad Signal Footprint:**
+   Analog signals had a broad footprint, meaning they could cover
+   a wide area and potentially interfere with other communications.
+   This was particularly problematic at higher altitudes, where the
+   signal could reach multiple towers spread over a large geographic
+   area.
+
+## Modern Digital Phones Modern digital phones use technologies
+like Code Division Multiple Access (CDMA) and Global System for
+Mobile Communications (GSM), which offer several advantages over
+analog systems:
+
+1. **Dynamic Frequency Management:**
+   Digital phones dynamically manage frequency usage, switching
+   channels as needed to maintain call quality and reduce interference.
+   This allows for more efficient use of the available spectrum and
+   minimizes the risk of network overload.
+
+2. **Efficient Handoff:**
+   Digital systems have advanced handoff mechanisms that allow
+   seamless transitions between cell towers. This ensures that as
+   an aircraft moves, the phone can maintain a stable connection
+   without causing strain on the network.
+
+3. **Compression and Error Correction:**
+   Digital signals are compressed and include error correction,
+   which improves call quality and reduces the risk of dropped
+   calls. This also means that digital phones require less bandwidth,
+   allowing more simultaneous connections without overloading the
+   network.
+
+4. **Controlled Transmission Power:**
+   Digital phones adjust their transmission power based on the
+   signal strength and proximity to the cell tower. This reduces
+   unnecessary interference and helps maintain a stable connection,
+   even at high altitudes.
+
+Despite these advancements, the FCC's regulations still prohibit
+the use of cellular phones while airborne to avoid any potential
+disruption to ground-based networks.
+
+## FCC Regulations
+
+The FCC enforces these restrictions to protect the integrity of
+cellular networks. The regulation, [specifically **47 CFR §
+22.925**](https://www.ecfr.gov/current/title-47/chapter-I/subchapter-B/part-22/subpart-H/section-22.925),
+states:
+
+> **47 CFR § 22.925 - Prohibition on airborne operation of cellular
+telephones** > > Cellular telephones installed in or carried aboard
+airplanes, balloons, or any other type of aircraft must not be
+operated while such aircraft are airborne (not touching the ground).
+When any aircraft leaves the ground, all cellular telephones on
+board that aircraft must be turned off. The following notice must
+be posted on or near each cellular telephone installed in any
+aircraft: > > “The use of cellular telephones while this aircraft
+is airborne is prohibited by FCC rules, and the violation of this
+rule could result in suspension of service and/or a fine. The use
+of cellular telephones while this aircraft is on the ground is
+subject to FAA regulations.”
+
+This regulation helps ensure that network performance is not
+compromised, a concern that applies to various types of aircraft,
+including gliders and hot air balloons.
+
+To address the demand for connectivity, airlines have developed
+in-flight Wi-Fi services that use controlled environments, such as
+picocells and satellite connections, to provide internet access
+without relying on ground-based towers. This allows passengers to
+stay connected without risking network disruption.
+
+## Future Outlook
+
+As technology continues to advance, there may be potential changes
+to current policies. Future solutions could address both technical
+concerns, allowing for more flexible use of mobile devices during
+flights. However, for now, the balance between ensuring safety and
+maintaining network integrity remains a priority.
+
+While technology has reduced some risks associated with cell phone
+use on airplanes, technical reasons still justify many of the current
+regulations. These restrictions, enforced by the FCC and applicable
+to all flying machines, help maintain network integrity and ensure
+a pleasant flight experience for everyone. We encourage readers to
+share their opinions and experiences on this topic.