Modern navigation systems, which are found in most of today's commercial aircraft, are made with low-power circuitry, which is more susceptible to interference than the vacuum-tube circuitry found in older planes. During landing, navigation systems receive radio signals from the airport to guide the plane to the runway. Recently, one plane with low-power circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop computer. Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop computers.
Which one of the following, if true, LEAST strengthens the argument above?
(A) After the laptop computer was turned off, the plane regained course and its navigation instruments and dials returned to normal.
(B) When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.
(C) No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board.
(D) Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.
(E) Planes were first equipped with low-power circuitry at about the same time portable electronic devices became popular.
I have some confusion regarding one of the options. Please help.
Navigation Systems
This topic has expert replies
- gmat_for_life
- Senior | Next Rank: 100 Posts
- Posts: 75
- Joined: Fri Jun 26, 2015 7:43 am
- DavidG@VeritasPrep
- Legendary Member
- Posts: 2663
- Joined: Wed Jan 14, 2015 8:25 am
- Location: Boston, MA
- Thanked: 1153 times
- Followed by:128 members
- GMAT Score:770
Boiled way down, the argument is that electronic devices can cause problems in the aircraft navigation systems of modern planes. (I'd likely make a simple arrow diagram on my scratch paper.: devices ---> disturb navigationModern navigation systems, which are found in most of today's commercial aircraft, are made with low-power circuitry, which is more susceptible to interference than the vacuum-tube circuitry found in older planes. During landing, navigation systems receive radio signals from the airport to guide the plane to the runway. Recently, one plane with low-power circuitry veered off course during landing, its dials dimming, when a passenger turned on a laptop computer. Clearly, modern aircraft navigation systems are being put at risk by the electronic devices that passengers carry on board, such as cassette players and laptop computers.
Which one of the following, if true, LEAST strengthens the argument above?
(A) After the laptop computer was turned off, the plane regained course and its navigation instruments and dials returned to normal.
(B) When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.
(C) No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board.
(D) Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.
(E) Planes were first equipped with low-power circuitry at about the same time portable electronic devices became popular.
So we want the answer choice that is least effective in strengthening that link. We'll go one by one.
A) After the laptop computer was turned off, the plane regained course and its navigation instruments and dials returned to normal.
Well, that certainly seems to strengthen the idea that the device was causing problems. I'm looking for the answer choice that doesn't strengthen the argument, so this is out.
B) When in use all electronic devices emit electromagnetic radiation, which is known to interfere with circuitry.
Again, this will strengthen the argument. We now have a clear mechanism for how this disturbance happens. B is out.
(C) No problems with navigational equipment or instrument dials have been reported on flights with no passenger-owned electronic devices on board.
Looks like a solid strengthener. While it isn't proof that devices are causing problems, it's certainly noteworthy that the navigational disturbances go away when there aren't electronic devices on board. C is out.
D) Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.
Here, we're told that there are devices whose radiation can reach the navigation system. That's a strengthener - how else could the devices cause the disturbance if they weren't close enough for their radiation emission to have an impact? D is out
(E) Planes were first equipped with low-power circuitry at about the same time portable electronic devices became popular.
This fails to address any causal connection between the devices and the navigational disturbance. (Imagine a simpler argument: planes began to experience navigational difficulties around the time that Taylor Swift became popular. It would be pretty silly to claim that Taylor Swift's popularity was, therefore, causing the plane's navigational problems. E is the answer.
- gmat_for_life
- Senior | Next Rank: 100 Posts
- Posts: 75
- Joined: Fri Jun 26, 2015 7:43 am
Hi Dave,
Thanks for your prompt response.
If we consider option D, 'Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.', nowhere in the argument core has it been mentioned that electromagnetic radiation causes interference in circuits. If we have a look at option B, it does state a correlation between EM waves and its effects on the circuits, thereby strengthening the argument.
So wouldn't option D be irrelevant to the argument in question?
Regards,
Amit
Thanks for your prompt response.
If we consider option D, 'Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.', nowhere in the argument core has it been mentioned that electromagnetic radiation causes interference in circuits. If we have a look at option B, it does state a correlation between EM waves and its effects on the circuits, thereby strengthening the argument.
So wouldn't option D be irrelevant to the argument in question?
Regards,
Amit
- DavidG@VeritasPrep
- Legendary Member
- Posts: 2663
- Joined: Wed Jan 14, 2015 8:25 am
- Location: Boston, MA
- Thanked: 1153 times
- Followed by:128 members
- GMAT Score:770
True enough, but in order for these devices to be causing problems, they have to be emitting something and that something has to be within range of the equipment it's potentially interfering with. D at least gives us that. I agree that it isn't a great strengthener - just because radiation is within range of circuitry doesn't guarantee that the radiation is causing problems - but we're looking for which answer choice would strengthen the argument least, and whatever D's shortcomings, they pale in comparison to E, which does absolutely nothing to strengthen the argument.If we consider option D, 'Significant electromagnetic radiation from portable electronic devices can travel up to eight meters, and some passenger seats on modern aircraft are located within four meters of the navigation systems.', nowhere in the argument core has it been mentioned that electromagnetic radiation causes interference in circuits.