Constant Cost Index

Hi Simbrief.

Not sure if I asked this before, but I keep getting the same Cost Index on all my flights.
CI 80 on Boeing and CI 60 on Airbus.
Now I do use custom airfraft profiles, but cost index is set to automatic, so it should not give any static values. I know it is dependant on different factors, but it does not seem to change regardless of route option, distance or flight level (mostly auto)…

Any idea why?
Again Thanks.


Hi, on your recent flights I noticed you have manually entered the following “Sched Flight Time” options:


All of these scheduled flight times are very short, much shorter than is possible to achieve. Remember that the scheduled flight time should be the planned “gate-to-gate” time, including taxi out and in. This is the time that is most often published on an airline’s schedule, for example.

SimBrief’s AUTO cost indexes will vary as needed to achieve the scheduled flight time you’ve entered, up to a specified maximum. By setting these low enroute times, the system is always going to plan the maximum cost index, which explains what you’re seeing.

If you aren’t entering the scheduled enroute time yourself, are you perhaps using SimBrief through a Virtual Airline or third party app? If so they might need to correct the scheduled flight time on their end.

Hope this helps,

Hello sir, thanks for answering.

I will try and explain how I do it, and then you can perhaps tell me what I am doing wrong and why?

I almost always use real world SOP from two particular company provided. One for Boeing 737-800 and one for Airbus A319/A321

Now I use a tool to estimate the ball park of enroute distance and time. Here is a link to it Flight Manager: Worldwide provider of international trip support and corporate flight handling tools & services.

This gives me an idea on what to set as scheduled time and in the example of ENGM to ENBR as inducated as “very short” in your feedback, it plays out like this.

  1. According to Flight Aware the real flight time is as low as 0:34 minutes and as high as 0.55 minutes.
  • All depending on weather, traffic etc. We all know this.
  1. When entering ENGM - ENBR with the ground speed of 450 into this tool, you get 0:38 minutes including 15 minute bias on ground.
  • That is pretty realistic and I have as mentioned use it as a ball park to estimate enroute time

So let me use Simbrief example

Scheduled time is generated to 1 hour 10 minutes:
Taxi out = 15 minutes
Taxi in = 10 minutes.

Taxi out on ENGM does not alot more than 5 minutes, less than or equal to 5 minutes at ENBR

Deduct 10 minutes from ENGM
Deduct 5 minutes from ENBR
= 15 minutes deduction

So basically, the logic is that you then deduct 15 minutes from scheduled time = 0 hour, 55 minutes

Correct so far?

Well what I do is this:

Take the time of 0:38 provided by the time and distance calculator which include 15 min bias
Set that as scheduled time
Since TAXI in and TAXI out is already set to 15/10 per default in Simbrief, ill just deduct 5 minutes from TAXI in time.

Now deduct those 5 minutes from scheduled time (which already include 15 minutes aka taxi out)
it results to 0 hours 33 minutes which is darn realistic in terms of time real world

Now the funny part is this…
It does not matter if I choose ENGM to ENBR or ENGM to what ever place in Europe, I always get CI 80 when choosing Boeing 737-800 and 60 when choosing A319 for example.

Am I completely wrong or is there any possibility there is a bug or broken logic somewhere? Could it be something with the stored aircraft profiles I am using, which by the way is created based on real world weight data.


If I’m honest, I feel like you’re slightly over complicating your life here. But anyways, a few things I noticed:

FlightAware and your tool are giving you the expected air time. Which is takeoff to touchdown, not including taxi out/in. I realize your tool states that it includes a 15 minute taxi bias but the numbers it’s giving do not support that claim.

As I said, SimBrief’s “Sched Flight Time” needs to be a gate to gate time. You need to include the taxi times in this number. So if you got 0:33 in your example, you then need to add the taxi out and in times to that number.

Let’s say you think taxi out at ENGM normally takes 5 minutes (a bit short if you ask me, pushback and start-up alone takes almost that long), and taxi in also takes 5 minutes (probably reasonable). That’s 10 minutes total taxi time, so you would do 0:33 + 0:10 and enter 0:43 into the “Sched Flight Time” option. Make sure to also enter 05/05 into SimBrief’s taxi out/in options as well so it knows what taxi times you’re planning.

For what it’s worth, I think it’s much simpler (and realistic) to look up the scheduled flight time for an airline flying this route, and simply enter that into the “Sched Flight Time” option. For example, NAX638 is a B738 flight that operates between these airports, and a quick Google search shows that they plan 0:55 gate-to-gate time:

I would just enter 0:55 in SimBrief, then set the Taxi out/in times to something reasonable depending on the airport (my feeling is 10 minutes out and 5 minutes in is probably a good guess for this flight). In other words, simply like this:


Hopefully this helps somewhat,

Thanks for the filled answer… I asked my training CPT and got confirmed that his operator uses block to block so that makes you absolutely correct. I will adopt that going forward. Company system handle clock times via the ACARS/ATSU and we normally always leave ETT unchecked since it adopts the clock on takeoff roll. That means the physical clock isn’t set always manually. Since the sim aircraft did not have ATSU yet (Toliss) the clock was manually started upon entering runway, this was a bad habit adopted from long time use of Boeing. Now with company SOP in mind, I will adopt block to block also by manually starting the clock timer before push.

While that is complete, it does not fully answer why the Cost Index is always set on 80 or 60 in the case of Airbus, long or short route seems to matter none.

Any idea?


Now that you are entering a more realistic time in the “Sched Flight Time” option, you should notice the Cost Index will vary a bit more.

If you want an example of this, try setting the “Sched Flight Time” to something much too long, for example 10 hours. You should see that the cost index will be set to the minimum (around 5 most likely).

Best regards,

Thanks, Did a check using reduced and increased time and the results was pretty consistent I must say.
Will accept this logic as solution fixed. Thanks for the assist mate : )

A319 Scheduled times

ENGM - ENAL Default = CI5 (1 hour 15 with 15 out / 10 in)
ENGM - ENAL Reduced 30 min = CI60
ENGM - ENAL Reduced 20 min = CI60
ENGM - ENAL Reduced 10 min = CI34
ENGM - ENAL Reduced 5 min = CI15

ENGM - ENAL Increased 30 min = CI5
ENGM - ENAL Increased 20 min = CI5
ENGM - ENAL Increased 10 min = CI5
ENGM - ENAL Increased 5 min = CI5

ENGM - ENAL Increased 1 hour = CI5
ENGM - ENAL Increased 2 hour = CI5

B738 - Scheduled times

ENGM - ENAL Default = CI17 (1 hour 15 with 15 out / 10 in)
ENGM - ENAL Reduced 30 min = CI80
ENGM - ENAL Reduced 20 min = CI80
ENGM - ENAL Reduced 10 min = CI63
ENGM - ENAL Reduced 5 min = CI41

ENGM - ENAL Increased 30 min = CI5
ENGM - ENAL Increased 20 min = CI5
ENGM - ENAL Increased 10 min = CI5
ENGM - ENAL Increased 5 min = CI5

ENGM - ENAL Increased 1 hour = CI5
ENGM - ENAL Increased 2 hour = CI5

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