If you are instinctively uncomfortable with the thought of concealed-carry teachers — personally, I have difficulties imagining Ms. Fitzpatrick from my kindergarten reading Good Night Moon, packing under her green cardigan — I would first suggest you attempt to reconcile your objection to trained, armed teachers with your (statistically likely) support for air marshals.
Following 9/11, most Americans demanded an armed undercover marshal on every flight. Little resistance presented to the idea, and expeditiously it became law. The new job of air marshal itself drew tremendous interest, likely aided by the pride of profession applicants expected. Administratively, the program has not run smoothly: concerns have centered around cost effectiveness, the actual percentage of flights which have a marshal on board, and employee mistreatment and discrimination, among others.
Yet objections to the armed security presence have remained minimal. Airplanes in flight are likely never again to be “gun-free zones”; they will instead approach “gun-mandatory zones,” and you likely are pleased with this.
Schools fall under federal “gun-free zone” law. Far more Americans support gun-free schools than support gun-free flights; a segment of the U.S. population thus exists which supports undercover air marshals yet rejects undercover “school marshals.”
Leave aside the emotion: does logical reasoning present grounds for this divergence in opinion?
Even prior to 9/11, airplanes were certainly no soft target. Today, someone wishing to do harm to an airplane in flight must breach several layers of security to board with a weapon, and further, can be expected to face physical confrontation with other adult (or sufficiently large teenaged) passengers. The ratio of physically capable passengers to the helpless or infirm is generally large in all but the most unusual cases; four to one seems a reasonably conservative estimate.
Finally, the perpetrator must deal with that trained, armed marksman that most of America insists be there.
The death toll from 9/11 dwarfs that of all combined school mass shootings over the past couple decades. However, the frequency of school shootings dwarfs the frequency of attempted and successful incidents of in-air attacks. Even with the 18 hijackers of 9/11 included, the number of school shooting perpetrators is greater.
A more ghoulish comparison — figuring the potential death toll from either situation — certainly seems to fall in favor of the flight being the more high-value target deserving of greater security resources. A passenger plane may carry several hundred passengers, and a successful hijacking may murder them all, while the worst U.S. school shooting resulted in 32 murdered souls.
Yet — it is not clear from the Newtown massacre that the carnage might not have reached the unthinkable body count of a downed plane had the murderer not chosen to end his rampage by committing suicide. He had the ammunition to continue his spree, and he did murder at least one adult hero who, unarmed, attempted to physically stop him. Only his psychological state brought the horror to an end at 26 deaths.
In Newtown, had a more “stable” psychopath attacked — perhaps a murderer prepared to die, yet not by his own hand, like the Mumbai terrorists — well, G-d help us. Considering the difficulty in bringing down a plane and the ease with which all of Sandy Hook Elementary could have been slain, the potential for death in both incidents is logically equal: everyone present.