Since the deregulation of airlines, delays at the nation's increasingl

Question

Since the deregulation of airlines, delays at the nation's increasingly busy airports have increased by 25 percent. To combat this problem, more of the takeoff and landing slots at the busiest airports must be allocated to commercial airlines.

Which of the following, if true, casts the most doubt on the effectiveness of the solution proposed above?

(A) The major causes of delays at the nation's busiest airports are bad weather and overtaxed air traffic control equipment.

(B) Since airline deregulation began, the number of airplanes in operation has increased by 25 percent.

(C) Over 60 percent of the takeoff and landing slots at the nation's busiest airports are reserved for commercial airlines.

(D) After a small mid western airport doubled its allocation of takeoff and landing slots, the number of delays that were reported decreased by 50 percent.

(E) Since deregulation the average length of delay at the nation's busiest airports has doubled.

BrightOutlookJenn · Accepted Answer

A student just asked via message for more detail on the reasoning process for this question, and to help with the choice between answers A and C. I'll share my thought process:

We have a very big leap from the evidence to the conclusion. The evidence says that airport delays have increased by 25 percent.  (Note to self: we have no idea - and definitely no evidence - on why these delays have increased.)  The author somehow jumps to the conclusion that we need to allocate more of the takeoff and landing slots at the busiest airports to commercial airlines.

My reaction:  ???? (scratching head) What???
Where is this conclusion even coming from?

What does the author assume is causing the delays??

He  must  think that the commercial airlines are causing the delays. Specifically, he must think that the problem is that the commercial airlines don't have enough takeoff and landing slots ... so if we can give them more slots (basically appointments on the calendar when they are allowed to take off and land) then this will alleviate the problem of delays. So he thinks.

What a dumb assumption. Sorry, author. There is  NO evidence  to back up this idea. If we can show that  anything else  (other than commercial airlines getting insufficient takeoff/landing slots) is the real cause of delays, we will prove what a dumb idea this is.

Answer choice  A  gives us some alternative causes of the delays. These causes have nothing to do with commercial airlines and their takeoff/landing slots. This is perfect - it proves how the author's idea would be pretty useless to combat the delays, since his idea doesn't address the real problems that are causing the delays.

Answer choice  C  gives us a fact about what percent of slots are currently assigned to commercial airlines. But we have no way to know if this is a sufficient percentage or an insufficient one. We have no other data (about how many slots the commercial airlines would actually need) to compare this to. So we can't use this to strengthen or weaken anything.

To generalize  ->  if the conclusion is based on an unproven assumption about the cause of some outcome, we can weaken the argument by finding  any good alternative explanation  to suggest that  something else entirely is the real cause  of the outcome.

bipolarbear · Answer

I go with option A.

The author assumes that a primary cause for the heightened delays is the lack of unoccupied landing and takeoff slots for commercial airlines. Thus, the author argues that the best method is to increase the number of slots. However, option A gives a different reason for the delays. If it is attributed to something other than the number of slots, increasing them would not necessarily help.

ChiranjeevSingh · Answer

Understanding the Passage

Since the deregulation of airlines, delays at the nation’s increasingly busy airports have increased by 25 percent.

“deregulation of airlines” – Seems some regulations have been eliminated in the airline industry.

Since that, delays at the nation’s busy airports have increased by 25%.

(I wonder why this would happen. Perhaps, there is more air traffic, or perhaps, there is more chaos because earlier regulations brought some order to the airports)

To combat this problem, more of the takeoff and landing slots at the busiest airports must be allocated to commercial airlines.

The author makes a recommendation to solve this problem. Which problem? The problem of increased delays.

The author says that more of the takeoff and landing slots at the busiest airports must be given to commercial airlines.

The statement uses “more”. more than what?

more than currently.

So, if currently 100 slots are given to commercial airlines, the author says more than 100 slots must be given to commercial airlines.

—

The author has not specified why he recommends this way to combat the problem. I mean, why would increasing the slots to commercial airlines solve the problem of delays?

Is the cause of delays that commercial airlines don’t have enough slots?

We don’t know.

And if this is not the cause of delays, the recommendation by the author is not expected to solve the problem of delays.

Understanding the Question Stem

Which of the following, if true, casts the most doubt on the effectiveness of the solution proposed above?

We’re looking for an option that casts the most doubt on the effectiveness of the proposed solution.

In other words, we’re looking for an option that most strongly indicates that the solution is not effective.

In other words, we’re looking for an option that most strongly indicates that allocating more of the landing and takeoff slots to commercial airlines at the busiest airports  is NOT an effective solution  to reducing the delays at the nation’s increasingly busy airports, i.e., X is not an effective solution to Y.

Predicting Possible Answers

1. One way to indicate the ineffectiveness of the solution is by playing on the difference between increasingly busy airports (where the problem lies) and busiest airports (where the solution is proposed). It is possible that the busiest airports are not the same as “increasingly busy airports”. In such a case, the proposed solution will not solve the problem at all!
2. Another way is to indicate that the problem is not at all around the lack of slots. So, giving commercial airlines more slots will not help.
3. Another way is to suggest that giving more slots to commercial airlines would mean fewer slots for non-commercial airlines. Fewer slots for non-commercial airlines would mean a lot of delays.

The Evaluation

(A) The major causes of delays at the nation's busiest airports are bad weather and overtaxed air traffic control equipment.

Correct.    This option indicates that the proposed solution is ineffective in solving the problem at hand since the problem is due to some other causes, i.e., bad weather and overtaxed ATC equipment. Thus, we have a reason to believe that allocating more slots to commercial airlines will not help in tackling the problem of delays.

(Some of you may notice that option A talks about “nation’s busiest airports” and not “the nation’s increasingly busy airports”. If you remember, the problem we’re trying to combat pertains to the nation’s increasingly busy airports.

How can this option weaken the proposed solution by talking about the nation’s busiest airports?

This option weakens since the proposed solution was also about the nation’s busiest airports. The option indicates that the solution may not work at the nation’s busiest airports. If the solution doesn’t even work where it is supposed to be implemented, we have a reason to doubt the effectiveness of the proposed solution.)

(B) Since airline deregulation began, the number of airplanes in operation has increased by 25 percent.

Incorrect.   This option is not relevant to us. Why?

Because it doesn’t differentiate between commercial airplanes and non-commercial airplanes. If the number of non-commercial airplanes had increased at a much greater rate than the number of commercial airplanes, we would have a reason to doubt the proposed solution. However, option B doesn’t give any such reason.

(C) Over 60 percent of the takeoff and landing slots at the nation's busiest airports are reserved for commercial airlines.

Incorrect.   I believe the reason many people mark this option is that they think in the following way:

1. This option says that a majority of the slots are already reserved for commercial airlines.
2.  Then, why give them even more slots?! 
3. Thus, we have a reason to doubt the proposed solution.
 
The second step is incorrect. Even if the commercial airlines have 80% of the slots, it may make sense to give them more slots if these airlines account for, let’s say, 90% of the air traffic.

Whether it makes sense to give commercial airlines more slots depends on a relationship between the slots allocated to them and the air traffic they account for.

Just the data on the number of slots given to commercial airlines is not helpful to determine whether giving them more slots is sensible.

(D) After a small mid western airport doubled its allocation of takeoff and landing slots, the number of delays that were reported decreased by 50 percent.

Incorrect.   Let’s first consider the following version of option D:

D1: After a small mid western airport doubled its allocation of takeoff and landing slots to commercial airlines, the number of delays that were reported decreased by 50 percent.

D1 says that allocating more slots  to commercial airlines  led to a reduction in delays at some airports. Thus, D1 supports the effectiveness of the proposed solution.

However, option D is about increasing the overall number of slots, i.e., increasing the capacity of the airport. Thus, option D is talking about a different way to reduce the delays.

Whether this different way worked or not has NO IMPACT on whether our proposed solution is an effective way.

(E) Since deregulation the average length of delay at the nation's busiest airports has doubled.

Incorrect.   This option has no impact on the effectiveness of the proposed solution.

All this option gives us is that the average length of delay has doubled. So, not only has the number of delays increased, the average length of delay has also increased.

Thus, the problem is more severe than we earlier thought.

However, this option indicates nothing about the effectiveness of the proposed solution; the option just presents another problem.

CARK · Answer

OA is A. But is there any difference between the term " nation's increasingly busy airports" used in argument and term " nation's busiest airports" used in correct option?

I understand that other options can easily be eliminated, but if we have option F : The major causes of delays at the nation's increasingly busy airports are bad weather and overtaxed air traffic control equipment.

What would be the answer A or F? Are we required to figure out such subtle differences in GMAT ?

Thanks

egmat · Answer

Hi CARK,

No, you will not need to figure out such difference in GMAT. Even in the current question, you are not supposed to figure out such difference. If you read the passage carefully, the conclusion talks about "busiest airports", the same as that in the correct option statement. Since our job is to weaken the conclusion, option A clearly does that by referring to "busiest airports".

As you can now think, if there were option F as you wrote, it would not be correct since it talks about "increasingly busy airports" whereas the conclusion talks about "busiest airports".

Remember in all argument questions (strengthen, weaken, evaluate, flaw), you need to have a RAZOR SHARP FOCUS on the CONCLUSION. Whatever premises say, if the conclusion is any different, then you need to pay attention to the conclusion.

Does it help?

Thanks,
Chiranjeev

KarishmaB · Answer

Since the deregulation, delays have increased by 25 percent. (We don't know what deregulation entails. We are not given what changed. We are also not given that deregulation is the reason for increase in delays. It has just been observed that since that time, delays have increased.)

To combat this problem, more of the takeoff and landing slots at the busiest airports must be allocated to commercial airlines. 
Solution is that more slots should be given to commercial airlines.

What will weaken that this will fix the problem? If we get to know that the reason for delays is something else - say weather phenomena - then will giving more slots help? Probably no. 
Only if the reason for increased delays is that the airlines have fewer slots than needed, then giving more slots will help.

(A) The major causes of delays at the nation's busiest airports are bad weather and overtaxed air traffic control equipment.

Correct. The reason for delays are different. More slots may not help. This weakens our conclusion.

(B) Since airline deregulation began, the number of airplanes in operation has increased by 25 percent.

If more planes are deployed now, more slots may actually help. Doesn't weaken our conclusion.

(C) Over 60 percent of the takeoff and landing slots at the nation's busiest airports are reserved for commercial airlines.

Irrelevant. Is 60% a high number or a low number, we don't know. If commercial airlines are responsible for 90% of the flights, then 60% seems low. If commercial airlines are responsible for 40% of the flights, then 60% seems high.

(D) After a small mid western airport doubled its allocation of takeoff and landing slots, the number of delays that were reported decreased by 50 percent.

What happened at a small airport is irrelevant. The nation's busiest airports are our concern.

(E) Since deregulation the average length of delay at the nation's busiest airports has doubled.

We already know the delays have increased. Doesn't weaken conclusion.

Answer (A)

Pankaj0901 · Answer

Dear Experts,

I have understood all the wrong answers expect Option A, which is the correct answer. But, I have two questions:

1. Fundamentally, how is it that only after the deregulation the bad weather and the overtaxing began that caused flight delays? Isn't the argument a bit weird if this option A is considered as true? If there were bad weather & overtaxing already, how suddenly it led to flight delays post the deregulation. Those factors must be causing delays before the deregulation as well.

2. Even if the major reason for delays is bad weather and overtaxing, so what? There could be many reasons for delays. For instance, say, 52 times out of total 100 delays (ie, majority: >50%) are caused by bad weather and overtaxing, there are still 48 other cases of delay that could be prevented if more slots are allocated to commercial plots. What if there are negligible non-commercial flights (say, only 2 non-commercial flights out of total 1000 flights that land at the busy airport. And so, we have 988 commercial flights) but 75% of the total parking slots in the airport are currently allocated for the non-commercial flights? 
Now, even if Option A is true, and keeping in mind the aforementioned superficial points, A doesn't seem to WEAKEN at all, but is just an additional information that is neither strengthening nor weaking the conclusion. I am surely missing something or thinking (dangerously) too much.

nightblade354 · Answer

On point one, although you are technically correct, I suggest that you do not overthink it. We are told that X happens and then we are told to weaken it. Y is an alternative reason and thus weakens it. Yes, we are told that the delays have been caused by people being overworked and weather in our answer, and the stems says the delays started after the deregulation. Maybe they came about post-deregulation? Maybe the additional 25% finally pushed these issues to a breaking point. In the end, it has no impact, in this case, on our outcome. On a harder question, it might.

On point two, you can read major as majority, as pointed out. As for the second issue at hand, all we want to do is weaken the argument somehow. Just because there are alternative explanations or further issues at hand is inconsequential. We have shown that logically this is not a good argument, and we have shown one example of it; you are showing a different issue. We are going too far down the rabbit hole on this one. Now, all that said, making these types of analyses and digging into the details to find all the issues is a really good way to improve your CR skills. We just have to remember the goal of the question, which in this case is to weaken the argument. If yes, then we can move on.

What we can do while solving is breaking the answer choice to make it an incorrect choice, which you do and is the best way to solve CR problems. But you take it one step further by adding additional data once we have assumed the answer choice. So we weaken the argument, but then you are weakening the new argument. This is where you go too far.

Pankaj0901 · Answer

Thank you  nightblade354 , this helps. No more questions on point one, but have a question on point 2.

I understand that we do not know if 60% is a high number or a low number. BUT, again, there are two perspectives, one of them would surely WEAKEN the conclusion.
 Perspective 1 : If commercial airlines are responsible for 90% of the flights, then 60% would be low. -  STRENGTHER  (Since we would need more slots for commercial flights, this would strengthen the argument.)
 Perspective 2:  If commercial airlines are responsible for 40% of the flights, then 60% seems high. -  WEAKENER  (We would already have many vacant slots for commercial flights, so adding more will not help.)

If major causes of delays are bad weather and overload, and ASSUMING that the availability of takeoff & landing slots  DOES NOT  impact the delay at all, the choice A  WEAKENS  the argument.
If major causes of delays are bad weather and overload, and ASSUMING that availability of takeoff & landing slots is  the second most reason  (or may be one of the significant reasons) for delays, then the choice A  DOES NOT WEAKEN  the argument.

I really don't want to go too far in thinking and assuming something beyond what is given in the premise, but in order to eliminate the options, I MUST think how I can eliminate the options - as you have also mentioned. It will be great if you can highlight where exactly I am going to far and why it is wrong to do so.

I am surely missing something. I would request you to please help me. Thank you in advance.

MartyTargetTestPrep · Answer

Regarding choice (C), as you showed, in order for (C) to affect the argument, we need more information than is provided by (C). So, (C) is not a weakener. It has no clear effect on the argument.

Regarding choice (A), notice that it says "THE major causes." "THE major causes of delays ... are bad weather and overtaxed air traffic control equipment" means that those are the MAIN causes of the delays.

So, (A) casts doubt on the effectiveness of the solution proposed by (A) indicating that things other than the availability of landing slots are the main causes of the delays. In that case, there is certainly reason to doubt that the proposed solution will be effective.

GraceSCKao · Answer

Hi experts avigutman IanStewart MartyTargetTestPrep I chose the correct option (A) in my practice, but I hope to discuss more about the incorrect option (B). It is an interesting option to me, since I think that it, with proper revision, could be a contender. From the stimulus, we know that delays at some busy airports have risen by 25 percent since the deregulations of airlines, and to address this issue, the author proposes allocating more takeoff and landing slots at the busiest airports to commercial airlines. By the way, this plan puzzles me a bit, because I remember that generally the airports at which commercial airlines operate are only for the use of commercial airlines. Military aircraft takes off and lands in military bases or airports exclusively for air force. Moreover, there is no such an airline as "a non-commercial airline," is there? ( An airline is a company after all.) Hence, I am surprised when reading the part about allocating "more" slots to airlines--I think that at such airports, most slots, or nearly 100 percent, have been allocated for airlines. But maybe I am being too narrow, since it is possible that there are some airports for the civic and military use at the same time. I hope to check the option (B). (B) Since airline deregulation began, the number of airplanes in operation has increased by 25 percent. The option seems to provide a reason why the delays have grown by 25 percent, but it does not offer a reason why the plan might not work. I wonder whether (B) could be better if it were changed as following: (B1) The number of airplanes that operate at these airports would increase significantly (B2) The number of airplanes that operate at these airports would increase by a significant degree that even the full slots cannot accommodate all of them Although (B1) says that the number of airplanes will grow much, we have no idea how great the growth will be. More slots could still reduce delays, as long as the gap between the number of flights/airplanes and slots are narrowed. So (B1) is not a contender. (B2) is better, isn't it? It suggested that even if airlines get all slots, the delays would still be severe, or even more severe. But this variant of the option (B) might be too obvious, so it might not appear in the real test. Thank you for your time and thoughts! Thank you for helping me learn.

avigutman · Answer

I think we need to dig a bit deeper into the proposed solution,  GraceSCKao :
 
The word "more" implies that some of the takeoff and landing slots, but not all of the takeoff and landing slots, are already allocated to commercial airlines at the busiest airports.  It's not useful for us to investigate or guess at which other entities are given takeoff and landing slots  (but my presumption was that they're given to private jets of the rich and famous).
We're looking for an answer choice that suggests that delays at the nation's increasingly busy airports wouldn't benefit from allocating more of the slots to commercial airlines. Side note: we don't know how "delay" is defined in this problem (is it minutes per person per day? Is it minutes per flight? This could matter in a different problem, because the number of people per flight may or may not make a difference, but since we don't know the definition, it cannot matter for this problem).

I'm afraid I don't see how  the number of extra planes in operation  impacts the effectiveness of the proposed solution.

GraceSCKao · Answer

Thank you avigutman for your explanations! I completely forgot the existence of private jets ha.

Though I was aware that who gets the remaining slots is not the key to answering the question, I could not help but feel curious about the issue. (Having such curiosity might be one of the reasons why I cannot answer CR questions in two minute. Yes the way delays is mentioned in the argument is abstract. My interpretation is that if the plane takes off or lands later than the scheduled time, it is a delay. But I am not sure about the growth rate "25 percent"--does it mean that the number of flights that have delays increases by 25 percent or that the amount of delay time rises by 25 percent? The stimulus does not have a clear definition. By referring to "the number of airplanes", I meant "the number of flights", since generally a plane in operation at an airport is responsible for one flight. That was my interpretation of the option (B). I thought that (B) says that the number of flights in operation has increased by 25 percent since the deregulations. I thought that my variant (B2) could be a contender because it can be inferred that more flights will worsen the delay issues, all other things being equal. (B2) The number of airplanes that operate at these airports would increase by a significant degree that even the full slots cannot accommodate all of them Thank you!

avigutman · Answer

I agree with the statement you made above  in red .
However,  GraceSCKao : Do you have reason to believe that allocating more of the takeoff and landing slots at the busiest airports to commercial airlines  would fail to combat the problem of delays ,  just because those delays are caused by an increase in the number of flights??  What am I missing?
I'm no expert on the impacts of different allocations of takeoff and landing slots, but I don't see why that impact would be nullified if the delays were caused by the sheer number of flights - I can still imagine some positive impact from reallocating the slots, especially if "delay" is measured as a product of   (because then a celebrity with a private jet who is delayed by 30 minutes can't "compete" with 200 people delayed by 30 minutes in a commercial flight - in fact, it might make sense to give ALL of the slots to commercial flights if "delay" is defined that way.)

jabhatta2 · Answer

Hi  GMATNinja   avigutman   IanStewart  - quick question. When one read's the purple conclusion - struggling to understand what is the author's opinion on commercial flights.

Does the author think 
-(i)-- Commercial flights are the  problem . So lets allocate MORE slots, so that commercial flights are given more time to sort themselves out

OR

Does the author think 
-(ii)-- Commercial flights are more  efficient   ( to non commercial flights). So lets allocate more slots to the more efficient airline type and reduce the number of slots to the inefficient type.

I argue -- one could interpret the purple conclusion as going either way

I thought (ii) made more sense thinking of this analogy

Same thing in this problem -- lets allocate MORE SLOTS to commercial airlines because commercial airlines are MORE EFFECIENT. (comparatively to non-commercial airlines)

IanStewart · Answer

Commercial flights are for a completely different purpose than non-commercial ones, so you can't replace one type of flight with the other, and the stem isn't saying anything about the efficiency of commercial aviation. When we talk about non-commercial flights, we mean flights by private jets and other privately owned aircraft, diplomatic and military flights, and probably cargo-carrying flights (depending what definition of 'commercial airline' you read). Commercial flights carry passengers. The one inference you can draw from the proposal -- the suggestion that airports can alleviate delays by allocating more slots to commercial airlines -- is that the commercial airlines are causing the delays. That makes sense at a busy airport, because it's usually the passengers that are responsible for delays.

jabhatta2 · Answer

Hi  avigutman  - if i understand your point above -- you are saying

i - Per  red , you agree that "if number of flights have increased by 25 %" == this is a potential alternative cause for the delays at busy airports

ii - However per the yellow highlight,  (red)  would  not be a weakener  because the original plan (of allocating MORE of the takeoff and landing slots to  commercial flights ) could still work in reducing delays.

But then, that thinking mentioned in the yellow highlight, would also apply to OA - (A), no ?

Just because  bad weather and overtaxed air traffic control equipment.  causes   MAJORITY   of the delays at the busiest airports, that doesn't mean the original plan (allocating more of the takeoff and landing slots at the busiest airports to commercial airlines) would fail to combat the problems of delay (as highlighted in the yellow above)

avigutman · Answer

Yes, I agree with you. The proposed solution  might  still be effective, even if the reason for the increase in delays is bad weather and overtaxed equipment. After all, none of us is an air traffic control expert, nor are we expected to be.
So, let's take a closer look at A and B, and compare the two:
 
Each answer provides an explanation for the increase in delays at the nation's increasingly busy airports. The increase in delays itself is not in question: we all agree that delays have increased since the deregulation. Does the reason for the increase in delays matter? Well, it must matter, because our job is to identify the reason for which  the proposed solution is the least likely to be effective .
I think it's  reasonable  to expect that the proposed solution is more likely to be effective if the reason for the increase in delays is an increase in airplanes or flights, and is less likely to be effective if the reason for the increase in delays is bad weather and overtaxed equipment. Do you disagree,  jabhatta2 ?

jabhatta2 · Answer

Hi  avigutman  - thank you so much for responding.

Between (A) and (B) - i agree that if (B) were true, the proposed solution (of allocating more of the takeoff and landing slots at the busiest airports to commercial airlines) would be more effective

If (A) were true, the proposed solution is not  so effective

If I understand, that's what is going on comparatively between (A) and (B)

However   on a tangent note --

I think given this doubt -- my instinct was to choose (B) over (A)

Since the deregulation of airlines, delays at the nation's increasingl

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Critical Reasoning (CR) Questions

Since the deregulation of airlines, delays at the nation's increasingl

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards