When Simbrief calculates a route and altitude is it taking into consideration the winds or is it just searching for routes? I wonder because sometimes it gives me lower altitudes than I would expect for the flight and sometimes rather long routes and am wondering if it has calculated that the winds are more favourable for a faster flight with a longer routing at a lower altitude as a result of winds.

It definitely does step climb, and I believe it also does take into account winds aloft. I have seen different altitudes on the same routes with the AT46, and I think it depends on the weather.

Peter

21 minutes ago, qqwertz said:

It definitely does step climb, and I believe it also does take into account winds aloft. I have seen different altitudes on the same routes with the AT46, and I think it depends on the weather.

Peter

I'm aware it does step climbs but I think that a function of its calculated fuel burn and relative weight. I'm wondering if the auto altitude is a product of weather expectations and relative fuel burm. For instance, earlier, in a TBM, it had me flying over France much lower than I would have expected and in a strange direction.

1 hour ago, Jazz said:

I'm aware it does step climbs but I think that a function of its calculated fuel burn and relative weight. I'm wondering if the auto altitude is a product of weather expectations and relative fuel burm. For instance, earlier, in a TBM, it had me flying over France much lower than I would have expected and in a strange direction.

Correct, step climb doesn't depend on wind. I found the following under "historical weather" in the Simbrief manual:

"For upper-level winds, SimBrief calculates flights using the appropriate upper-level winds forecast "

Now, that may just be related to timing, not cruise level. I guess the Navigraph forum would be the right place to find out.

 

5 hours ago, Jazz said:

I'm wondering if the auto altitude is a product of weather expectations and relative fuel burm.

I also had a number of examples recently of altitudes given by Simbrief lower than expected (or achievable given the plane weight and range) and each time - when in flight - I could verify that if I were to climb higher, I would end up having stronger headwinds leading to lower speeds and higher fuel consumptions. So unless it was a strange coincidence, I would think Simbrief does indeed take weather into the equation, both for routings and altitudes.

16 minutes ago, Bernard Ducret said:

I also had a number of examples recently of altitudes given by Simbrief lower than expected (or achievable given the plane weight and range) and each time - when in flight - I could verify that if I were to climb higher, I would end up having stronger headwinds leading to lower speeds and higher fuel consumptions. So unless it was a strange coincidence, I would think Simbrief does indeed take weather into the equation, both for routings and altitudes.

I used to see Simbrief totally disregard altitudes specified in the FAA DB, but that appears to have been fixed. I'd say I've never seen Simbrief seem to do this via altitude, but maybe it does. It does have the data - it's in most OFPs for the +1k/-1k spread for wind and ISA - it seems to populate the most frequent FlightAware route without considering time of day.

On shorter sectors, I think it has an optimistic view of how high you can get. I've seen Simbrief give altitudes 5-10k higher than the LOA/FAA pref route altitude. 

It does take winds into account for cruise level. If you check the wind forecast table, you'll see that the winds are more favorable at your level compared to lower or higher. Of course weight is also a deciding factor.

This is unlike the aircraft's FMC which only takes weight into account for optimum flight level, not winds.

6 hours ago, Bernard Ducret said:

I could verify that if I were to climb higher, I would end up having stronger headwinds leading to lower speeds and higher fuel consumptions. So unless it was a strange coincidence, I would think Simbrief does indeed take weather into the equation, both for routings and altitudes.

That's what I have tried a few times but it's always been inconclusive. Sometimes this is the case and other times the winds are similar or more favourable. However, this could just be a discrepency between between weather sources between simbrief and MSFS.

I have been wanting to get to the bottom of this for a very long time.

1 hour ago, Jazz said:

I have been wanting to get to the bottom of this for a very long time.

It does take winds into account for altitude planning. That's known.

Besides, it wouldn't be very useful in calculating fuel or at all even if it didn't include winds.

Edited December 4, 20232 yr by threegreen

4 minutes ago, threegreen said:

It does take winds into account for altitude planning. That's known.

Besides, it wouldn't be very useful in calculating fuel or at all even if it didn't include winds.

Quite