It has long been known that a single plane burns much more fuel than a fleet of cars. This fact has led some to believe that limiting flights is a direct solution to the problem of air pollution. I strongly disagree with this point of view, since air travel is highly efficient and only a minority of people buy plane tickets.
First, planes are used for long distance trips and are a good use of fuel due to their high speed achieved in the low air density of high altitudes. Keeping all that in mind, there are no alternatives that would enable the crossing of oceans and allow people to shave off entire days and even weeks of their travel time. Hence, it would be impossible to limit the use of public flights, since even if it was done, the consequent use of land vehicles and sea vessels that would ensue would be less efficient and even more harmful for the environment.
Second, as opposed to planes, which are predominantly owned by commercial airlines, most cars driven today are in private use. It means that flights are already optimised to the fullest degree, whereas people in cities could opt for getting about by means of public transportation, which is more realistic and sensible. Furthermore, people use planes only in cases of highest need and urgency, yet cars are used for everything from commuting to grocery store trips. Therefore, limiting car rides and encouraging the use of buses and trains is more likely to yield positive results as far as air quality goes.
Admittedly, there are also aircraft possessed privately, the use of which could be limited for the common good. Although it could bring potential benefits for the environment, private jets constitute only a small fraction, and could be neglected in the final analysis.
In conclusion, the phasing out of planes would come with a number of other problems the resolution of which would only exacerbate the situation with air quality.