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On-board cellphone signal detectors?
During the departure taxi phase on a United 777 at Dulles yesterday
(4/28), the cabin crew made the usual safety announcements and instructions that all electronic devices must be turned off until the plane had climbed above 10,000 feet (or whatever is the specified altitude. A few minutes later, one of the cabin crew (at least, I thought it was the cabin crew, not the cockpit, but can't be sure) came on the PA system and said something like "Our signal radiation detector [or some such term] is indicating that an electronic device in the cabin has not been turned off. If this device is not turned off, we will have to return to the gate and that passenger will be removed." [And of course I immediately had a panicked thought, "OMG, my cellphone is buried in my bag up in the overhead -- did I _really_ turn it off when I stuffed it in there?".] So, are there really any such "signal radiation detectors" (or whatever they said) in routine use on any current airliners, from the cockpit or the cabin crew area? Or was the cockpit/cabin crew just yanking our chain? I guess I'm very skeptical about there being any such instrumentation, because: 1) Given the immense variety of rf signals that must leak from all the different types of cellphones and consumer electronic devices, designing such a detector seems like a real challenge. 2) Especially because it would have to distinguish offending signals from all the aircraft-generated signals that must be simultaneously bouncing around inside the aircraft. 3) Returning to the gate would seem like to generate major expense and disruption in terms of gate access, schedule delay, potential taxiway interference, revised flight planning (?), potentially even refueling -- it's just hard to believe they would really do it (especially given the high probability of a false positive in a system like this). 4) And, if there really were some passenger with an operating device in their pocket, it would be pretty trivial for them to surreptitiously turn it off during the return taxi; and then what is the airline to do, once they're back at the gate? Search all the passengers, trying to find which of a hundred cell phones was the guilty one? Just doesn't seem realistic to me . . . ??? |
#2
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On-board cellphone signal detectors?
On 4/30/2010 1:37 PM, AES wrote:
During the departure taxi phase on a United 777 at Dulles yesterday (4/28), the cabin crew made the usual safety announcements and instructions that all electronic devices must be turned off until the plane had climbed above 10,000 feet (or whatever is the specified altitude. A few minutes later, one of the cabin crew (at least, I thought it was the cabin crew, not the cockpit, but can't be sure) came on the PA system and said something like "Our signal radiation detector [or some such term] is indicating that an electronic device in the cabin has not been turned off. If this device is not turned off, we will have to return to the gate and that passenger will be removed." [And of course I immediately had a panicked thought, "OMG, my cellphone is buried in my bag up in the overhead -- did I _really_ turn it off when I stuffed it in there?".] So, are there really any such "signal radiation detectors" (or whatever they said) in routine use on any current airliners, from the cockpit or the cabin crew area? Or was the cockpit/cabin crew just yanking our chain? It's possible, if they were specifically looking for relatively high-power signals occuring in the cell phone bands. That would be a fairly good indication that the switched-on cell phone was somewhere in the cabin. Electronic equipment in general, which could be producing emissions at just about any frequency - well, it would be a lot more difficult to make that assessment with any real certainty. Bob M. |
#3
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On-board cellphone signal detectors?
In message AES
was claimed to have wrote: During the departure taxi phase on a United 777 at Dulles yesterday (4/28), the cabin crew made the usual safety announcements and instructions that all electronic devices must be turned off until the plane had climbed above 10,000 feet (or whatever is the specified altitude. A few minutes later, one of the cabin crew (at least, I thought it was the cabin crew, not the cockpit, but can't be sure) came on the PA system and said something like "Our signal radiation detector [or some such term] is indicating that an electronic device in the cabin has not been turned off. If this device is not turned off, we will have to return to the gate and that passenger will be removed." It's entirely possible one of the flight attendants spotted something and lied about how it was detected just for giggles. It's also entirely possible likely that they have some piece of equipment which reacts to certain frequencies. A iDEN or GSM phone near an improperly shielded speaker or amplifier can cause some interference, for example. It's possible that some non-critical system reacts similarly, creating an unintended (and likely unreliable) detector. |
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On-board cellphone signal detectors?
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