Maintenance Ratio

Hello There!

Now i know I must try to keep my maintenance ratio on the higher side of 100%, however my current ratio is 99.9% Is this still acceptable? or do I have to remove a round trip?

You may need to try and create a bit more maintenance time. Sometimes, just delaying a departure at the end of your maintenance gap may do the trick (if slots are available for this), depending on how you scheduled your flights. If you don’t, then chances are that down the line, the aircraft won’t get enough repairs and drop to 50% ‘health’, at which point it can’t fly anymore. This may take months though at that maintenance ratio, but still, it could be an issue.

You could also try to swap one of the round trips with a slightly shorter one so you gain a few minutes on your maintenance window.

Even a Maintenace-Ratio of over 100% may cause aircraft failure. Always try to spread the maintenance periods equally over the days.

Let your flight schedule with those 99.9%, it’s ok. :)

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Didn’t want to start a new topic but I have a related question.

I had maintenance ratios of 105 and 118 on two aircraft with Amethyst (the defaul contractor). I wanted a higher maintenance ratio so I changed to Helvetic Maintenance which is apparently Excellent Quality but my maintenance ratios remained the same!? So I am going to pay more for the same maintenance???

Anyone can provide some sort of explanation for this? I thought if you increase the quality from Average to Excellent you’d get a higher maintenance ratio?



What this means is that the overall quality of your aircraft will remain at a slightly higher level, because the quality of the maintenance is better. At least, that’s the theory… ;)

To get a better maintenance ratio %-wise, you need to increase efficiency, not quality. Since both Amethyst and Helvetic have the same efficiency - average, your ratio didn’t change. Higher quality, on the other hand, allows your aircraft to be maintained to a higher level, I.e. with Amethyst your aircraft would never have a 100% condition (with ratio close to 100%), while with Helvetic you would get 100% condition even if your ratio is as low as 101%. At leas that is how i understand it.

As far as I know, this is correct. Higher quality, same speed means your aircraft’s condition (which I referred to as quality in my previous post, apologies for the confusion) will be better if the quality is better. This comes at the price of having higher maintenance costs per unit repaired.

I am right at understanding that with Helvetic I can schedule the schedule with 95% Maintenance Ratio but the aircraft condition is never going to reach 50% where it can’t fly anymore? I don’t get it - efficiency is clearly displayed as a % but for quality I have to guess how my aircraft will cope??? This doesn’t make any sense, who would choose quality instead of efficiency then (except by not knowing how it works like in my case)?

Anyone has a clue how low I can go with Helvenic - 90? 95? 85? I’ve never used them so any experience is better than my experience…

Nope. You cannot go below 100%, but the intervals between maintenance taking place can be longer before reducing the plane’s condition to a level at or below 50%, where it would otherwise be grounded. So a higher quality means you can implement schedules that include longer “stints” between one or another maintenance period.

More "speed" in turn leads to a higher ratio, at least usually.

I see. Well that makes a bit more sense but still choosing High Quality contractor seems like an awful idea as you gain almost nothing for your extra money. It is probably a good idea that some of that information is added to the wiki as this is not explained at all and probably I am not the only one who did not understand it until now.

Anyway thank you for the info and I am switching to African in two weeks, just a pity that I’ve just wasted a few thousand AS$ on nothing .


when I changed from the default contractor to African, I noticed that several flight schedules had a higher maintenance ratio. But you have to put everything in the balance…

Back then I mostly flew domestic and regional routes, read: short flights. Changing to African allowed me to squeeze an extra flight in a tight flight schedule. But now I also have many medium and long(ish) haul flights. On these flight schedules I now have high maintenance ratio’s that I can’t fill up properly anyway.


Added when editing: but I am still happy with African ;)

Quality means how low you can go with your performance ratio! I’m pretty sure I have in most of my planes one (daily) turn more than you all! :D

FENCC: To clarify this once again - If you have a symmetrical schedule with daily maintenance windows, you may be able to go VERY low (e.g. 101,x%), with low regard to "quality". The bigger the gaps between maintenance, the more important "quality" becomes. Simple as that.

I’m going to add this to the wiki in the course of the next days.

I hope the new section in the wiki will help to reduce the present uncertainty:

Thanks, as long as it is correct, it is a great guide.

I’m aware of what you mentioned, plotz, but it’s not totally correct and what I wrote was well-thought - but I don’t want anyone to schedule like I do. :P


If I understood Plotz well…

… an efficient maintenance contractor will bring your plane from 80% condition to 100% condition in less time (than an average maintenance contractor)

… and when hiring a high quality maintenance contractor, you can fly longer before the condition of your plane drops from 100% to 80%.

If you say this isn’t correct, perhaps you can enlighten us with the correct explanation


No, I can’t. Didn’t I wrote I can’t? Yes, I did!

No you didn’t, you said "I don’t want".

Fun aside, there are enough options for everyone to enjoy. You can’t put a number on this per provider because the number depends on the aircraft type, number of rotations between maintenance windows, etc. Too many variables to have a suitable reflection of cost. So, instead there’s a quasi-baseline which is then deviated from with two or more factors. That baseline, as pointed out, is average/average/average. Better quality costs you some speed and money, whereas better speed costs you quality and money as well. I think the collection available right now suits just about everyone’s needs, whether it’s an airline that does maintenance during its hub waves, an airline that has flights departing back-to-back or an airline that needs to fit maintenance on a single day. All should be well served with at least one, and probably several of the providers. Which is the best for you? Try and find out! The fact that Avia and African seem to be the most frequently used ones should be a clue.