TOPCAT takeoff performance table

[skelsey 765]

7 hours ago, alex98 said:

I have seen situations where Topcat was very conservative and computed lower than expected max TO weights, even at airports like LIME (Bergamo).

I find it to be very pessimistic as soon as the airport is 1000ft amsl and/or there is obstacles and/or the runway is short. Sometimes you would not be able to get out of places like Skiathos or TNCM... And this was checked against the FPPMs I have.

As Dan mentions above, bear in mind that just getting off the runway is only half the equation: you also have to be able to make the required obstacle clearance in the second segment. I'm not familiar with Bergamo particularly, but it's possible that the local terrain (or obstacles) causes a problem with this.

Likewise, Skiathos is very limiting, and it's quite common for departures to require a tech stop (e.g. at Thessalonki) to uplift fuel as especially in the summer it is often impossible to depart with sufficient fuel for a sector of any length (e.g. to the UK).

[ahsmatt7 1,199]

11 hours ago, WebMaximus said:

As far as I understand TOPCAT will take this into account for you after you put in all the figures meaning it will only show you flex temps that will be OK with your current TOW.

Looking at the pictures, I see thst now. However, I have seen it where it gives you the data for all the runways and that's what I meant and wait i was referring too. I didn't even know you could get a second picture like that only showing data for one runway. Anywho, that's all my 2 cents!

[JoeDiamond 67]

On 6/28/2017 at 3:32 AM, WebMaximus said:

This since there are a number of temps to choose from where the higher the temp, the shorter the runway margin. Is it simply up to the captain to decide and if so, based on what exactly?

Our real world takeoff performance software only give us one assumed temperature based on the max available derate, not a whole list like TOPCAT does.  The derated thrust is calculated using a weight 2000 pounds higher than the planned weight so there is some additional margin built in.

[WebMaximus 372]

37 minutes ago, JoeDiamond said:

Our real world takeoff performance software only give us one assumed temperature based on the max available derate, not a whole list like TOPCAT does.  The derated thrust is calculated using a weight 2000 pounds higher than the planned weight so there is some additional margin built in.

Thanks for sharing Joe.