An unusual spot airfare sale puts the Big Apple in the spotlight.

Three airlines serves New York’s LaGuardia Airport with frequent daily nonstop flights from Atlanta - AirTran, American and Delta. And all three offer a blanket round-trip rate of $238 to the city on trips completed by Aug. 2, 2013.

There are few rules to qualify which makes this deal particularly valuable. The trio require an advance purchase notice of 21 or more days in advance. The special rate is valid on any day of the week (based on sale seat availability). But the biggest bonus is no blackout dates. New York City is one of the most desirable routes from Atlanta and especially for cool autumn visits, the long Thanksgiving weekend and surrounding the year-end holidays. Normally rates climb higher during these peak seasons, but not in the case of this today-only deal. For instance, one-way tickets of $119 can be purchased from any of the three carriers. This gives travelers the opportunity to create a custom trip using a combination of carriers.

The not-so-good news? There is no ticket-by date on this offer, indicating that the special price could vanish at any moment. If a trip to NYC is on your wish list, buy tickets immediately and save with this flexible offer.

Sale airfares are always subject to change. Every seat on every flight is not offered at the lowest rate. Since only a limited supply of seats is available, act quickly to make your purchase.

I recommend starting the search for available seats at Kayak.com vs. calling an airline directly. You can also search for the sale at travel websites such as Expedia or Travelocity, etc. Airlines can discontinue or pull a sale price without notice when the offer does not have a “ticket-by” date or when the offer is deemed “sold out.”

— Clara Bosonetto is a retired travel consultant.