With infinitely long upgrade waitlists and fewer upgrades clearing, United elites are spending more time in economy class, especially on hub-to-hub routes.

As a Premier 1K member, just 10% of my eligible flights this year have received Complimentary Premier Upgrades (CPUs) to first class. I’ve long thought CPUs were the best benefit of Premier 1K status, but with complimentary upgrades being few and far between, I’ve considered revisiting my elite status strategy.

However, hope is not lost. Today, I’ll show you a day-of-departure upgrade tip that you can use to snag one of the last first-class seats on the plane — even if you’re halfway down the upgrade list.

What happens to upgrades when departure time approaches

NICOLAS ECONOMOU/NURPHOTO/GETTY IMAGES

One quick disclaimer — I’m sharing this tip merely from my own experiences and observations, having traveled with United. There’s no guarantee that this will work for you, and we haven’t tested this tip across MileagePlus accounts. Remember this tip the next time it looks like you won’t be getting a complimentary upgrade on the day of your flight, but don’t bank on it always panning out.

Now, with that out of the way, let’s dive in.

At the most rudimentary level, there are two variables at hand as the departure time for your flight approaches: First, the number of empty seats in first class; and second, waitlisted passengers for first class.

As the departure time approaches, United tends to open lower first-class fare classes, including the “PZ” fare, which means that an upgrade to first class is confirmable using PlusPoints or miles.

For example, let’s look at a flight from Los Angeles International Airport (LAX) to Kahului Airport (OGG) in United’s Expert Mode. Expert Mode shows the fare classes available on a given flight.

Three days ago, there were six seats available in first class (indicated by “J6”). However, upgrades to first class were unconfirmable (indicated by “PZ0”).

This screenshot was taken three days ago. UNITED APP

Now, let’s look at the same flight two hours from departure.

UNITED APP

Even though there are just two seats now in first class (indicated by “J2”), there is now one seat available to confirm an upgrade to (indicated by “PZ1”).

By checking on the day of departure and applying either PlusPoints or miles, an upgrade could be cleared — potentially leapfrogging a lengthy upgrade waitlist.

In my experience, there must be at least two empty first-class seats for this tip to work. Again, this is indicated by the “J2” marker in United’s Expert Search mode.

Related: Why Premium Plus and higher fare classes are the secret to United upgrades

Using this tip on award tickets

By traveling in first class, you will likely have an additional baggage allowance. KYLE OLSEN/THE POINTS GUY

This tip can also be used on award tickets if seats are released.

Earlier this month, I traveled from Baltimore/Washington International Thurgood Marshall Airport (BWI) to San Francisco International Airport (SFO) using miles. On the morning of departure, I saw that United had released a seat to the “I” fare class (business saver). For just 12,500 extra miles, I upgraded my economy-saver ticket to a business-saver fare.

If the I-fare class becomes available on your flight — as in the example flight below — you might be able to snag a seat on a Star Alliance points currency for a lower price.

UNITED APP

Turkish Airlines Miles & Smiles charges just 12,500 miles for United’s first-class domestic tickets. And yes, that fare is available on Hawaii flights.

Incidentally, the above flight to Southwest Florida International Airport (RSW) has 32 passengers on the upgrade waitlist. By reserving the “I” fare or confirming an upgrade using the “PZ” fare, you could jump the waitlist and confirm a first-class seat right now.

Related: The ultimate guide to getting upgraded on United Airlines

Bottom line

As the departure time of my flight approaches, I regularly refresh the available fare classes and the upgrade waitlist to see if I can snag a first-class seat using my PlusPoints. If you don’t have PlusPoints, you can use miles to confirm an upgrade when the “PZ” fare is available on a paid ticket.

I use this strategy when my position on the upgrade waitlist clearly shows that I won’t be getting upgraded.

This year alone, by using this tip, I’ve been able to lock in upgrades on the following flights:

San Francisco International Airport (SFO) to Ellison Onizuka Kona International Airport at Keahole (KOA).
Newark Liberty International Airport (EWR) to San Francisco International Airport (SFO).
San Francisco International Airport (SFO) to Kahului Airport (OGG).
Charlotte Douglas International Airport (CLT) to Denver International Airport (DEN).
Seattle-Tacoma International Airport (SEA) to Chicago’s O’Hare International Airport (ORD).
Los Angeles International Airport  (LAX) to Honolulu’s Daniel K. Inouye International Airport (HNL).
Honolulu’s Daniel K. Inouye International Airport (HNL) to San Francisco International Airport (SFO).
Baltimore/Washington International Thurgood Marshall Airport (BWI) to San Francisco International Airport (SFO).
Austin-Bergstrom International Airport (AUS) to Dulles International Airport (IAD).

The next time it looks like you’re not going to get upgraded, try this tip and see if you can snag a seat up front.