There is not a great need for the further reductions in flight time that can be afforded by the SST over the near-sonic jets. Furthermore, the time gain by the SST will be counteracted by reduced in-flight comfort and, on the average, by an increasing difference in airport distance between supersonic and competing subsonic services. Nevertheless, most businessmen in a great hurry and some tourists are likely to prefer the SST on conveniently scheduled flights and at equal fares.
However, for utilisation reasons only some of the SST flights can be conveniently scheduled and the SST's will—for 15 specified reasons—be so grossly uneconomical in competition with subsonic aircraft that the condition of equal fares cannot be complied with without exceedingly high subsidies to be covered by the taxpayers in all SST-operating countries. The subsidies must continuously increase mainly because of
—improvements of competing subsonic aircraft in operating cost—and ability to use more centrally located airports and
—increasingly adverse sonic-boom reactions (as the operation grows and the SST's, as is normal, become heavier and create higher boom intensities) by people on the ground, including potential SST passengers.
As the SST enterprise will thus be an economic failure, most of the aspects that are claimed to be advantageous in the event of an SST success, in particular prestige and improved national economy, will instead turn into pronounced disadvantages: loss in prestige and an economical burden.
Over and above this, supersonic aviation will
—most likely be much less safe than subsonic aviation,
—possibly subject passenger and crew members or their off-spring to harmful effects of cosmic radiation,
—seriously counteract, probably make impossible, the urgently needed improvement of flight safety in aviation,
—hamper the brilliant prospects now in sight for making aviation a really cheap and convenient means of mass transportation, and
—retard the expansion of civil aviation.
People in general are prepared to put up with a certain amount of noise—in confined areas and mainly during the working hours of the weekdays—if it is an inevitable by-product of a necessary, an important, or a profitable activity. But supersonic aviation, which will cause serious noise disturbances day and night, 365 days of the year, in unprecedently vast areas, is neither necessary, nor very important, nor profitable. Thus, the introduction of supersonic flight would mean that hundreds of millions of people would not only be seriously disturbed by the sonic booms, often to an extent detrimental to health, but also have to pay out their own money to keep the noise-creating activity alive, and in addition, have to accept a much less safe and cheap civil aviation than would otherwise be possible to achieve.
Therefore, the consequences are such that, once the supersonic era has begun, the general public will always strenuously oppose it. There will be an unprecedented tension between aviation and the public. Intense efforts will certainly be made to switch back to all-subsonic aviation. The cost of such a reversion will be fantastic and rapidly grow the longer the supersonic era prevails.
Obviously, it lies in the best interest also of civil aviation to prevent introduction of supersonic flight in its presently suggested form.