Real life maintenance

In terms of maintenance there could be a lot of improvement in the game, as this is quite a complex subject. In real life, you normally distinguish between line and base maintenance. Line is done on the tarmac while the aircraft is between flights. Base maintenance is scheduled and normally takes a few days to several weeks and is done in hangars. Add then also the overhaul of items to this, which basically brings used items back to new level.

In AS there is only line maintenance.

Maintenance contractors

As part of the strategic decisions, you can select different maintenance providers. This will allow you to trade between faster maintenance, though the trade-off is higher cost or a faster degradation of your your aircraft. You can select your prefered provider under Operations - Maintenance.

The system automatically picks a provider when you create your airline, and in most cases that is just fine. Selecting a different provider at a later stage might mess up your flight plans, because if the new provider is less efficient, your MX ratios might fall below 100%. Depending on your fleet age different provider have a different optimum. You'll have to run a few tests yourself to find the best provider for your specific airline.

Be aware, that you can only change the provider every two weeks. So once you change it, you will have to live with it for a certain period before you can change again.

The different providers not only have different prices and efficiency, also the quality is a point. Higher quality providers means that the aircraft deteriorates at a slower speed and keeps its rating at a higher level for a longer time (compared to other providers and performing the same flights).

Flight plan

As I have already briefly mentioned before, the main task about maintenance is done during the flight planning.

Above is a flight plan with three daily breaks of roughly two hours for maintenance. Why are these MX breaks necessary?

When you get a new aircraft, the aircraft condition is at 100%. Get an aircraft on the used market and you will get a condition stated with that aircraft. With each flight performed, your aircraft condition will decline. There is a certain amount of "damage" done per take-off, and a certain part is based on the duration of the flight.

The more flights you perform without a two hour break in between, the lower your aircraft condition will become. If the condition falls below 50% then your aircraft is no longer airworthy and you face an AOG. Your aircraft will no longer fly and planned flights get cancelled (for which you have to pay cancellation costs.).

If that happens, you have to manually schedule a transfer flight to another airport, leave a long enough time window for maintenance to be performed and ensure you have money to pay for that. Once the next scheduled flight then comes up at that airport, it will resume flying.

MX Ratio and aircraft condition

On the fleet page you can see the condition and maintenance ratio just below the age of the aircraft. The percentage on the left is the aircraft condition, which should be as close as possible to 100% and better not fall below 50% to avoid the grounding of your aircraft.

The second percentage number is the MX ratio. It states how well you utilize your machine. If this value falls below 100% then, over time, the maintenance provider will not have enough time to fully bring back the condition to 100%. Eventually you will end up with an AOG and you will need to schedule a manual MX break. If the MX ration is much higher than 100%, you don't utilize your plane as intensive as you could, and your fixed costs allocation per flight will be higher than they could be, making it more difficult to be profitable.

Maintenance time window

Click on the green bars on the flight plan page above to see the turnaround times of your plane. At the bottom you can see the maintenance time window. As it is here the case, the window is more than two hours and it is enough time for the engineers to do their job.

Although you could schedule a singe time window per week and end up with a MX ratio above 100% and still have your aircraft grounded. As stated above, the condition slowly degrades with each flight. Wait too long and those 100% will fall below the threshold of 50% and your aircraft is grounded.

Plan at least one window per day, if possible more than one to always keep the aircraft condition at a high level. Each time a flight is performed, the condition is one of the elements that influences the flight rating and thus also the airline image. Higher ratings will allow you to charge higher prices.

MX costs

Right after a MX break and just before take-off of the next flight, your aircraft condition is adjusted and the cost of that maintenance check is charged to your bank account. You can see that on your bank account (see above at the bottom). You can see the number of damage points that have been worked on and the cost related to it.

MX cost penalty

Now be aware that you can have up to three different MX categories and pay the base price for the maintenance.

On the aircraft page you can see the maintenance category under the technical specification. The number shown has no significance, but each aircraft type with the same category number is calculated as the same category. Usually this means, that the same family of aicraft share the same category. Like all aircraft types from the A320 family (A318 up to A321neo) share the same category.

Now if your airline operates more than three different categories, then each additional category will increase your maintenance cost by 15% for ALL aircraft. Therefore it is advisable to not have many different categories with just one or a few aircraft, but rather have fewer categories with more aircraft of the same type.

Once an aircraft is shown in your fleet page as available (I believe aircraft on delivery are not yet counted), it will count as a category. If you have it leased out, or offered in the market it will no longer count.