Right after I posted an explanation of why there are very few airfare mistakes these days, we get two in a row — first tons of premium cabin award space available on Singapore Airlines (which looks like it’s being honored without any difficulty) and second United MileagePlus awards that touch Hong Kong for 4 miles (it’s too early to say for sure what will happen, though apparently at least two people have already flown on the deal).

Both of these examples are consistent with my explanation — that ‘fat finger’ discounts where a zero or two are most commonly left off of a paid airfare are mostly a thing of the past. The system that airlines load their international fares into now contains a warning screen that flags fares that look too low. So it’s only airlines without good processes and training, whose employees don’t understand the tools they’re given, that generally load these types of fares anymore.

It’s mostly other types of glitches that happen — due to a currency conversion problem or routing rules, for instance.

Or in these cases, what looks like an inventory screwup during a reservations system cutover, and a technical problem at United.com calculating the number of miles for an award.

And these prove that even if the old sort of lucrative “$33 instead of $3300 business class fare” mistake doesn’t happen much anymore, at least not with North American or European airlines, mistakes are far from dead.

Which is why general principles remain important to understand in advance, so you’re ready when something comes along.

Get in on the deal right away. You really can’t wait, you don’t know whether deals will be gone in 5 hours or 5 minutes. Don’t wait until your spouse is out of a meeting, or try to get 5 family members all traveling together o the same flights. Don’t spend an hour discussing what you’d want to do while you’re in Singapore, or whether you really need to include an additional segment to Kuala Lumpur. You have to jump right away.

These things are usually refundable. Consider how much money is at stake, if it’s 4 United miles plus taxes then you may take the plunge even if you were going to be out the cash if you couldn’t use the award. Most of the time, though, even non-refundable airfares are cancellable for 24 hours. And most often airlines have been more than happy to refund non-refundable tickets rather than have to honor an expensive mistake. Get in right way, don’t try to arrange the perfect trip. That’s different from how we normally plan, but so are these opportunities.

Don’t book non-refundable travel plans around your ‘score’. After the British Airways India deal for fuel surcharges and taxes only, which wasn’t honored, the Department of Transportation said that for travel involving the US airlines were required to cover costs that passengers incur in reliance on an airfare being honored. So even if a mistake deal wasn’t honored, the airline would be on the hook to reimburse non-refundable costs. Still, I’ve always believed it’s best to take a wait and see attitude on these things rather than fight for reimbursement. Just give it a few days before doing any additional planning to see if the deal is going to happen or not.

Don’t call during the deal. This is the one thing that will most upset your fellow frequent travelers. Most of the time calling a customer service agent won’t actually make a different in getting a deal pulled early, but it might, and really there’s almost never an urgent need to contact a travel provider right away. You don’t actually need seat assignments now, before you even know if your tickets are going to be honored. Let the deal run its course. Don’t be responsible, even in the remotest chance, for alerting the powers that be about what’s going on.

Should you call once a deal is gone? Usually it’s best to wait and see what’s happening, since talking to a customer service agent isn’t going to do much good, the frontline agents probably won’t know what’s going on before you do. And having anyone touch your reservation could present problems, a rogue agent might cancel you and there’ll be little you can do to reconstruct the trip. So usually just take a deep breath. That said, it’s hard to imagine calling will do any damage for anyone (except, in the limit, yourself). Once in a great while contact can be helpful. After the November 2005 currency conversion error at Expedia where the Hilton Tokyo was being sold for $2 ($3 for the Executive Floor), folks that emailed in and got written confirmation that their bookings were in order had those bookings honored while many who had not written in had their bookings cancelled.

Don’t threaten to sue. The Department of Transportation has new rules that more or less require airlines to honor paid fares once ticketed at the price quoted. I actually do not like this rule as it applies to mistake fares (and there’s not really litigation on this point yet in any case.) Getting in on a deal like this is buying an almost free lottery ticket. If the travel provider honors, you’ve got an amazing once in a lifetime style opportunity. If they don’t you’re really no worse off. I generally don’t begrudge a travel provider if they cancel right away. Once several days or a week has gone by I start to rely on the booking and I expect it to be honored. But if cancelled with clear communication and in a timely manner, I don’t see much harm or foul. I get in because if someone is giving away free trips somewhere cool, I’d love to be a part of it. But I don’t get angry if I don’t get aamzing free stuff at someone else’s expense.

Should you share a deal? The more people that know about a deal, the higher volume it is, the quicker it’s going to be noticed and get pulled. Travel providers have people assigned to monitor Milepoint and Flyertalk, deals don’t stay secret. (Most of the time they get pulled anyway, but the broader a deal is shared the fast the process may get accelerated.) Personally I’ve always taken the approach that you should book what you want for yourself. Don’t be greedy, you aren’t entitled to the deal forever. And once you’ve gotten what you would potentially want, share it so others can (potentially) benefit as well.

But doesn’t letting more people in on a deal reduce the chance that it’ll be honored? Sometimes. In my experience, more often than not Marriott will push back against honoring a mistake rate. And the more expensive it is, the less likely they are to honor. On the other hand, there can also be strength in numbers, with the more people involved the more people potentially angry, complaining, raising a stink, so the greater downside to a travel provider in not honoring a deal. There’s really no way to know in advance how the situation will turn out. Sometimes a deal is small and flies under the radar, sometimes a small group is less likely to see the deal honored.

The best deals come from the least likely of sources. I got an email heads up from a reader about the United Hong Kong issue. Apparently a limited amount of information about intra-Asia bookings had previously been posted on Flyetalk, with no responses, and then the content was deleted by the person who posted it. So it didn’t get any traction there. That person had seen reference to the issue on the Chinese frequent flyer site Flyertea. Very few people would have seen it if the information hadn’t been posted here. I’ve found a few good ones in my time, such as a currency conversion error for flights departing Papeete. But for the most part the very best deals haven’t come from experienced users in small closed communities, they’ve come from large numbers of people searching for large amounts of travel. And the new members often find the best deals.

Way back mistake deals would be found by a few people, and that would be that. The internet changed the scale, because opportunities spread virally. Technology then allowed most airlines at least to limit the frequency of mistakes.

It’s a back and forth, but there are general principles. Stay alert. Stay plugged in. Grab your lottery ticket when you can. Wait on the sidelines to see what will happen. Sometimes you win and sometimes you don’t, but there will be more opportunities that come along in the future.