Instead, there are a number of options available to you to ensure you will receive a more comfortable seat before you even arrive at the airport.
1. Paid upgrades
The absolute easiest way to ensure an upgrade is simply to pay for it. If you've already booked a cheap seat and are considering paying extra to ensure a more comfortable one, you should be able to upgrade to a higher class either on the airline's own website, or by calling them and paying the fare difference. Be aware that the cost may be substantial — to change from a discount economy up to a first-class ticket on a long-haul flight could be 10x the price.
But also be aware that some airlines will offer discounted upgrades either by invitation in advance of the flight or at airport check-in. Keep an eye on your email for communications from the airline for a possible invitation. The option may also be listed on the 'Manage My Booking' section of the airline's website.
Some airlines like Singapore, Cathay Pacific and Etihad also have the option to bid for an upgrade using platforms like OptionTown and Plusgrade. If invited to bid, you can enter an amount online that you are willing to pay for an upgrade (the airline will set minimum and maximum bid amounts possible). This option is sent out to a number of eligible passengers by email and, if say 50 passengers bid for five available upgrade seats, the top five bids will be successful and those passengers then proceed to pay for the upgrade.
Related: Should you bid for an upgrade on Norwegian?
If you are invited to bid, obviously only pay the amount you are willing to part with for the upgrade. The maximum bid range amount may be close to the amount required to upgrade the flight without needing to bid, so you could secure the upgrade immediately rather waiting on the auction results.
If you only want to pay the minimum amount, a good trick is to consider offering slightly more than the minimum amount (i.e. if the minimum bid is $200 consider bidding $220). If a number of other bidders only offer bid the minimum amount, then your slightly higher amount will be processed before theirs.
You may also notice 'Paid Upgrades Available' signs at the check-in counter (or be advised of this by a check-in agent), depending on the type of ticket you have purchased, the seats available and the size of your traveling party. The price is likely to be fixed so you would need to determine on the spot if the price is suitable for you.
Try and research the upgraded product in advance so you can decide what it is worth to you. It's also worth confirming exactly what benefits a last-minute paid upgrade will include such as additional checked luggage, lounge access, priority boarding and whether the upgrade will earn loyalty points at the original fare class or the upgraded fair. Some airlines don't offer all the benefits of an upgraded fare for last-minute paid upgrades.
Related: Can you negotiate for a cheaper upgrade?
2. Using points to upgrade
Using points, rather than cash, can be a very cost-effective way to move to a superior cabin. The problem is that upgrades can be much harder to secure even if you are willing to part with a chunk of miles to do so.
Airlines like Qantas allow their frequent flyer members to submit an upgrade with points request at any stage and then process upgrades at the last minute for any unsold premium cabin seats. Airlines do this in order of status and ticket type, meaning if you don't have any status and are on a cheap ticket type, you are unlikely to be successful in an upgrade bid on popular routes. But at least you will only have the points deducted if your upgrade is successful.
3. When to upgrade
If you are planning to use points to upgrade and it is dependent on award availability, it's best to check if there are upgradeable seats available either as soon as possible (i.e. when you book the cheaper seat) as award availability can disappear very quickly. Many airlines also offer additional unsold premium seats as awards (and therefore upgrades) last minute, so try and check regularly in the seven days before your flight departs.
For paid upgrades for the best piece of mind you should be paying the upgrade earlier rather than later. If you are happy to take some risk you may score a discount by waiting for a bid invitation or inquiring at the check-in counter.
Related: Declining an amazing upgrade — TPG reader mistake story
