This is my response to the EU consultation "Aviation package for improving the competitiveness of the EU Aviation sector". You can find the consultation here: http://ec.europa.eu/transport/modes/air/consultations/2015-aviation-pack...
The purpose of the consultation was to consult all interested parties on possible measures that can reinforce the competitiveness of the EU aviation sector. However, I decided to take a bit more critical approach and to most questions just answered "no opinion" and only to the last question which was "Are there any other issues you would like to highlight in relation to this initiative?" I answered like this:
Despite emission reductions from automobiles and more fuel-efficient and less polluting turbofan and turboprop engines, the rapid growth of air travel in recent years contributes to an increase in total pollution attributable to aviation. In the European Union, greenhouse gas emissions from aviation increased by 87% between 1990 and 2006. 
Aviation represented a 3.5% share of total anthropogenic forcing in 2005 (90% likelihood range of 1.3–10%), excluding AIC, or a 4.9% share (90% likelihood range of 2–14%) including AIC. Those are pretty big numbers in themselves but given the forecasts of traffic growth the overall radiative forcing will be 1.7 times greater in 2020 than that calculated for 2000. If we also take into account technological advancing, in 2050 the aviation RF will be probably 3.2 to 4 times greater than in 2000. 
This kind of growth is unacceptable. The European Commission recognizes according to their web pages about climate change that "To prevent the most severe impacts of climate change, the international community has agreed that global warming should be kept below 2ºC compared to the temperature in pre-industrial times. That means a temperature increase of no more than 1.2°C above today's level".  Aviation should not be an exception to this goal.
Aviation promotes long distance travel with how fast it is, but that combined with a not-so-good rate of radiative forcing per kilometre means single trips can amount to relatively huge amounts of radiative forcing. It is not a sustainable mode of travel and that's why the growth in its market share is so worrying.
In my opinion, EU should abandon all programs for improving the competitiveness of aviation and instead focus on lessening its environmental impact and doing it in such a way people won't just change to using foreign airlines. Also, less environmentally detrimental alternatives to aviation should be promoted, such as video conferencing.
And about using biofuels, they might come at the cost of deforestation if farmland is used in their production. These kinds of "hidden costs" should also be taken into account.
 "Climate change: Commission proposes bringing air transport into EU Emissions Trading Scheme" (Press release). EU press release. 2006-12-20. Retrieved 2008-01-02. http://europa.eu/rapid/pressReleasesAction.do?reference=IP/06/1862
 Lee, D.S., et al., Aviation and global climate change in the 21st century, Atmospheric Environment (2009), doi:10.1016/j.atmosenv.2009.04.024