How to enhance your flight without paying full price

Airfares change moment to moment and day to day. Search for a Los Angeles to New York nonstop one-way in business class and the fare could be $499 one minute and $1,999 the next. It used to be that airlines gave away their premium seats as a perk for loyal customers, but now they prefer to get whatever the market will bear. I check multiple times as far in advance as possible and snag a deal when it appears. I’ve noticed recently that airline apps remember your last search so it’s as easy as hitting the search button again and again to see if fares have changed.

Often, on domestic routes, nonrefundable business or first-class seats are just twice the cost of economy class rather than three or four times as much as they once were. As with nonrefundable economy class fares, you’ll pay $200 to change or cancel your flight.

American, Delta and United let passengers use miles (15,000 to 20,000) plus a copay of $75, on lower-48 domestic routes, to upgrade from economy. Sometimes an upgrade is available immediately when you call the airline’s award desk, but usually you’ll be put on a waitlist.

How far in advance you book, the price of the economy fare, and the time you check in for the flight may affect your chances. Upgrades on flights to Hawaii and international destinations will cost more miles and higher copays, and other airlines besides those mentioned also allow mileage upgrades.

As with airfares, the number of miles or points needed to book a frequent-flyer award seat will vary day by day. I recommend calling the awards desk rather than going online to search availability. Last year I was looking for business-class award seats on British Airways and found none online, but when I spoke to someone on the phone there were lots of options. That said, American was offering, on its app but not on its website, “online only” business and first-class awards at greatly reduced mileage, so it’s a good idea to try both methods. Check multiple times before committing.

If you have good credit but don’t have enough miles in your account, the fastest way to earn enough for a business-class ticket is to get a new credit card offering sign-up bonuses after you charge a specified amount to the card, usually $3,000 in the first three months after approval.

Checking in online for an Alaska Airlines flight last year, I was offered a $50 upgrade to first class on a Seattle-to-Los Angeles flight. You’re darn right I took it. Waiting in line to board an Etihad Airways flight, I was approached by an agent who asked if I would like to upgrade from business to first class for $500.

That one I didn’t take, but you get the point: be alert to, and ask about, last-minute upgrades. Do it when you check in at the airport. And don’t ignore emailed upgrade offers: American sends me these all the time, mostly on shorter domestic flights. TAP Air Portugal sells upgrades to business class at the ticket counter or gate for about $400 to $500 per flight, depending on load factors.

Consolidators are like the T.J. Maxx of business and first-class airfares. I’ve never used one, but my friend Ken did recently on a New York-to-London trip in business class for 50% less than Virgin Atlantic was asking online.

Consolidators have been known to cease operations without warning, but one that’s been in the business for decades is Planet Amex (planetamex.com, no relation to American Express).

Four dozen carriers (Air New Zealand, Etihad, Fiji Airways, Hawaiian Airlines, Qantas, SAS and Singapore Airlines among them) offer upgrade auctions through PlusGrade.com.

Check the site for the whole list, but you must bid on each airline’s site where you’ll see rules and procedures, with some allowing upgrade bids on award tickets and some offering instant upgrades as well as auctions.

Although some airlines give away fewer free seats in business and first class than in the past, passengers with higher status in frequent-flyer programs do get upgraded for free at times, and those folks also have higher priority on waiting lists for mileage upgrades.

Oh, and one other way: be nice, dress well.