So-called “error fares” are not always that! How to tell if it’s a real one.

Yesterday I pointed out that you can use Kayak Explore to dig out some bargains. There are certainly some fantastic opportunities to travel around in the current era, and I fully encourage you to take advantage of the low prices now.

But I've also had my attention drawn to many websites claiming to spot “error fares” very regularly. I say they claim to spot it because they don't say where they sourced their information. If you didn't know already, in the air miles or travel blogging community, one of the biggest bragging rights of anyone is to be the source of error fares. So when I see some some websites and its followers retweet/share certain deals claiming a longhaul fare under £300 is a mistake, it certainly raises my eyebrows.

What follows is a basic guide to help you tell when a price is a cheap valid fare, and when it is a mistake.

Components of an air fare.

Air fares are almost always comprised of the following:

  • Base fare
  • departure country taxes
  • departure airport service charges
  • arrival country taxes
  • arrival airport service (occasionally)
  • airline service charges (“fuel surcharge” – sometimes has the code “YQ” or “YR”.)

If you have an itinerary with connections en-route, then you may need to add extra costs into the departure country taxes and departure airport ‘service charges'.

A mistake fare is one that accidentally misprices or omits one or more of the components above. But what should each component cost? If you are particularly studious the most potent way to find the individual breakdown of these prices is to use ITA Matrix for which I wrote a 3 part guide. But below is a summary.

For economy class tickets in sale periods, the base fare can go as low as $1. This is very, very common, especially when airlines try to poach the consumer market of its competitor. For instance, British Airways selling fares from Amsterdam or Frankfurt to another far-away destination, because they know consumers need a very strong reason to add in an extra 3-5 hours of travel compared to the non-stop offerings of KLM and Lufthansa.

But for business and first class, it is very difficult to tell what the base fare should be. My rule of thumb is if the base fare is anything below $0.20 per mile for a long-haul business class flight, then it is probably a mistake. This equates to $600 for a 3000 mile trip for example.

The country and airport taxes can add up to as much as $150+ on long-haul itineraries. The exception is if your journey starts in the UK, then expect to add in another $100 (£70) on top. I wrote a while back a guide on calculating UK Air Passenger Duty, though it's a little out of date on the prices. However, the method of calculation remains the same.

Then comes the black art of fuel surcharges. How airlines decide on their surcharges are beyond incomprehensible, but in the current days of cheap oil, my estimate is around $50-$80 per passenger for a single transatlantic or transpacific crossing. Intra-continental flights you can expect around $5-30 per sector. I did not source these number from anywhere, it comes from years of obsessively observing air fares.

So if you add those numbers up, if a long haul economy class fare is in the order of $250 or so, then it probably is not a mistake. If it is business class, then around $850 is my guideline.

Type of error fares.

Broadly speaking, mistake fares will be caused by one of the following:

  • Incorrect currency conversions – this could be a dramatic currency flotation after an airline has filed a fare, or their website simply being programmed incorrectly.
  • “Fat finger” mistakes – an airline only has control over its base fare and the fuel surcharges, and often a manual entry is wrongly keyed in.
  • Fuel dump – this is more often than not a deliberate action by the customer, but airlines do sometimes screw up with their coding and omit fuel surcharges. If the route is fairly innocuous and the fuel surcharge is missing, it's probably the airline's fault.

What to do if you think you spot an error fare.

Don't call the airline. Don't call the airline. Don't call the airline! 

Just book it and think about your plans later! If it is a mistake, most airlines try to cancel them anyway so don't be surprised if it does not get honoured.


Travel bloggers and websites often try to claim some notoriety by spotting error fares. Using the guidelines in this post, you can assess with confidence whether it really is one or not.


Do you have any other tips for spotting error fares? Do you agree with the information presented here? Let us know your thoughts below!


About Tim

Tim is an engineer and a nerd who analyses every travel deal, travel hack. He has travelled to around 90 countries and also speaks Spanish, Portuguese and Mandarin.

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