Bullish bets are ascending on Delta Air Lines Inc. (NYSE:DAL) this afternoon with traders scooping up calls at a rapid-fire rate. As of 12:44 p.m. EST today the airline issue has seen roughly 30 000 calls cross the tape -- about four times its average midday call volume. For comparison fewer than 5 100 DAL puts have traded thus far. Grabbing the most attention has been the March 11 call which has seen more than 10 500 contracts change hands -- mostly at the ask price hinting at buyer-driven volume. Furthermore implied volatility on the back-month call was last ...