The FlightStats.com website is a really useful tool — not just for tracking flights, to see whether they’re on time, and looking up historical flight reliability data (which is how most savvy fliers use it) but also to look up availability of seats on specific flights, including availability by specific “fare classes” which are the letter codes of the different buckets of inventory that airlines use.

That may not seem like something that matters to you, but it’s incredibly useful! Here are some examples of how you can use the information.

• For awards:
  
  • Say that you have Delta miles and want to know whether Saudi Arabian has business class award space from New York JFK to Riyadh.

  • Or you have Chase Sapphire Preferred points and want to know whether it makes sense to transfer those to Korean in order to redeem for a first class seat on the A380 from JFK to Seoul.

• During Irregular Operations: You want to search for flights that have availability, whether it’s wide open or just a single seat for sale, in order to tell your airline how to get you home. Maybe you’re trying to go from San Francisco to Washingtn Dulles and United says everything is sold out. But you find 1 seat flying to Kansas City of all places and then on to DC. Or you’re flying up from Atlanta, your plane goes mechanical, and you see seats on a Delta flight. Knowledge is power in knowing what to ask for that the agents might not proactively offer to you.

• To find the lowest fares: You know that there’s a $500-ish fare to Istanbul. In fact, it’s $200-ish plus taxes and fuel surcharges, and you’re looking to find it on Delta. Delta has it published as a “T” fare. So you want to go searching for flights with availability (a number greater than 0) in the “T” bucket. Just search flights on FlightStats for flights that have T availability, and those flights ought to price as-desired, provided you’re also meeting advance purchase, minimum stay, and any other restrictions like specific days of the week you can travel on the fare.

• To make same-day confirmed changes: United will allow you to change your flights ($75 for general members and Premier Silvers, free for higher level elites) beginning 24 hours prior to scheduled travel, to any flight within 24 hours of your request, provided that the same booking class as your existing ticket is available on the flight you want. Rather than hoping for a helpful agent, you can research for yourself what flights you can same-day confirmed onto.

FlightStats allows you to search availability up to 299 days out. While it pulls data from Sabre, it does not offer access to American Airlines inventory.

Here’s how to use it.

1. Create a free account, since you need to be logged in to access the availability feature.

2. Under the “Flights” menu, choose Flight Availability

3. Click the ‘advanced’ button so you can specify airline (and for that matter, search connections via a specific city)

Here’s a search for space on Alaska Airlines between Seattle and Los Angeles on November 7, a day I picked at random.

The results show a list of flights. Remember, I restricted the search to only find flights on Alaska. You’ll see flight number, airline, departure and arrival times, and also a rating of the flight’s reliability.

I clicked the arrow on the left side of the results for the 10am flight, and got full details of availability by each fare ‘bucket’.

There are “at least” 7 first class seats available. Alaska won’t display more than 7 seats in a given bucket, so when you see a seven that means “7 or more.”

What do the different classes mean? 7 “F” (full fare first class) seats are available, at least. There are also 7 “U” seats which means that confirmed upgrades are available. And there are 2 “A” seats meaning two first class award seats — bookable with Alaska miles or miles from any of Alaska’s partners.

All of the coach revenue booking classes, from Y on down, have plenty of availability. The only booking class that’s not showing 7 is “W” — that shows 4, and is the bucket for coach awards. There are 4 economy award seats open on this flight.

How do you know, though, what the different classes mean, especially for award and upgrade classes? This system doesn’t show those ‘special classes’ for all carriers, but it’s available for more than a handful.

With thanks to the KVS Tool FAQ (I’ll be reviewing KVS Tool in a future post), here are some notes on award and upgrade booking codes that are searchable using the FlightStats website.

Aerolinas Argentinas: “U” (business class award), “X” (economy award), “I” (business class upgrade)
Aer Lingus: “U” (business class award), “T” (economy award)
Aeromexico: “R” (business class upgrade)
Aeroplan: “R” (business class upgrade)
Aircalin: “O” (business class award), “X” (economy award)
Air Europa: “Z” (business class award), “A” (economy award)
Air France: “O” (business class award)
Air Tahiti Nui: “A” (first class award), “I” (business class award), “W” (economy award), “Z” (business class upgrade)
Alaska Airlines: “A” (first class award), “U” (first class upgrade), “W” (economy award)
Avianca: “A” (business class award), “Z” (economy award)
Bangkok Airlines: “Y” (economy award)
Brussels Airlines: “I” (business class award or upgrade), “X” (economy award)
CCM Airlines: “X” (economy award)
China Eastern: “A” (first class award), “D” (business class award), “I” (economy award)
China Southern: “P” (first class award), “I” (business class award), “O” (economy award)
Czech Airlines: “Z” (business class award), “E” (economy award), “I” (business class upgrade)
El Al: “P” (first class award), “X” (business class award), “E” (economy award), “A” (first class upgrade), “R” (business class upgrade)
Etihad: “R” (first class upgrade), “X” (business class upgrade)
Gol: “I” (business class award), “X” (economy award)
Gulf Air: “P” (business class award), “T” (economy award)
Hainan Airlines: “A” (business class award), “S” (economy award)
Hawaiian Airlines: “U” (economy award), “P” (first class upgrade)
Icelandair: “Z” (business class award)
Korean Airlines: “A” (first class award/upgrade), “Z” (business upgrade)
Martinair: “W” (economy award)
Saudi Arabian: “A” (first class award), “D” (business award), “L” (economy award)
Shanghai Airlines: “O” (first class award), “I” (business class award), “X” (economy award)
Tarom: “Z” (business class award), “X” (economy award)
Transaero Airlines: “E” (economy award)
Turkish: “J” (business class upgrade using Miles&Smiles miles)
Virgin Australia: “H” (business class award)
VLM Airlines: “O” (business class award), “P” (economy award)

Note that “upgrade” booking classes generally apply to using the miles associated with the airline’s own frequent flyer program only, using miles on partner airlines will generally imply a different booking class (e.g. Star Alliance upgrades usually pull from award booking classes).

Let’s have a look now at Korean. Searching New York to Seoul I come up with the following on the Airbus A380.

There are 4 first class award seats open. Wow, that’s generous. I sure wish Delta allowed their miles to be used for awards in international first class! Lucky I have Chase Ultimate Rewards points…

There’s also 4 business class upgrades, so I can upgrade if I’m buying an eligible fare and using Korean Airlines miles.

Unfortunately this system doesn’t show Korean’s business class award space, which would be ideal for the Delta Skymiles crowd — you cannot search for Korean Airlines business class awards online unless you have an account with Korean that has enough miles in it to claim the award. And Korean inventory may differ slightly from what a Delta agent will offer. So you still have to call Delta and hunt and peck (and of course Delta applies much more draconian blackout dates to awards on Korean than Korean applies to its own members).

All in all, a useful tool for searching for flights, finding lowest fares, and scouring for awards and upgrades. Definitely bookmark-worthy.