In my opinion the only tactful way of "marketing" the safety aspect would be for a one-time ad from US Airways thanking the crew, the passengers and the all the various EMS folks for all their efforts in avoiding what could have been a huge tragedy.
An ad in major markets thanking the passengers, crew and EMS is what should happen NO MATTER WHAT... On a side note...
I do agree with all the comments about it being tacky to advertise around the basis of an event like this, and there is a ton of truth to that. I also would never suggest that US should start advertising "only" about safety, but it isn't something that I think should be totally avoided. It's at least worth a mention, even if only on a subliminal basis - example - imagine an ad where the flight crew is walking towards their airplane, and the audio says "...our professional experienced flight crew..." Professional and experienced implies safety.
There is so much power in advertising. Advertising "reinforces" behaviors and beliefs about a product or service. Continental's advertising tells me that they care about customer service, that they have one of the newest fleets in the USA, and that when other airlines are going to cheapen the customer experience, they arent.
Southwest's advertising tells me that the price I pay is the final price, and that they aren't going to nickel and dime me, or charge fees that most airlines charge. In many airports, you approach this advertising as you walk towards the US Airways gates. Southwest is very effective in relaying their messages...
American's advertising tells me that I can travel in comfort around the world.
US is not carving a niche out for itself, and I think in the future this could be a big mistake. By not defining themselves, they are going to end up being the carrier of last resort... Regardless of all the initiatives US is trying to implement to be RELIABLE, SAFE, CLEAN, ON TIME, ETC.
I do agree with everyone, to campaign on safety alone would be a huge mistake - but to work it into an advertising campaign while it is fresh in people's minds would be very powerful.
In any case, this is MOOT as we know US doesn't advertise, and US will always be destined to just attract the customer who doesnt have a choice, or the one who gets the lowest priced ticket on Expedia - while others will actually develop brand loyalty, reinforced and reminded by the company's advertising...