[Daffynition]

Some of their more memorable slogans:

1974 – Delta Is My Airline
1980 – Airlines Are the Same. Only People Make the Difference.
1984 – Delta Is Ready When You Are
1984 – Delta Gets You There (also: Delta Will Get You There, Delta Gets You There with Care)
1987 – We Love to Fly and It Shows
1992 – Ready When You Are
1994 – You’ll Love the Way We Fly
1997 – On Top of the World
2005 – Good Goes Around
2010 – Keep Climbing

[PAR35]

I would have guessed earlier on “Delta is Ready When You Are”

Just checked, and I was right - 1968.
https://www.delta.com/content/www/en_US/about-delta/corporate-information/trademarks-slogans.html

Before that in the late 50s - “The Airline with the Big Jets”. Although I rode on one of their last prop planes a decade later (they went all jet in 1970). DC-7 service from Atlanta to Dallas. With stops in Columbus, Jackson, Monroe, and Shreveport.

[SaveFerris]

[ 2010 – Keep Climbing ]

2018 - Where’s the Phisohex and the Chlorine Bleach?

[Robert A Cook PE]

2018. Delta. Going down for your pleasure.
Fly Delta. Jet’s for you.