Flygprestanda

[dynamite dean]

hello I have posted in the tech log forum but just to get a braoder reply whilst I wait for a reply from flgprestanda itself I'll post here.

I am flying to a place and the flyg gives worse case scenario .v1 etc for a MTOW . However I am leaving empty. Simple question as i am new to this peculiar software I am not happy using V1 VR V2 with such a large difference. The other crew member just says just use the nearest ...well in our case its the MTOW figs verses the GURU of 12 kts lower for th V1 ...what do others do? The idea of doing overspeed take offs when you dont have to on what is a very short runway seems more sensible to me.

:ok:

[Paradise Lost]

Having established what climb gradient you need to clear your obstacles, check in the AFM that you will achieve that gradient at your proposed lower take-off weight, then use the tab data for V1/VR/V2 etc.
GURU should give you all that data anyway if you have entered the parameters accurately.

[Empty Cruise]

Flygp figures give you a MTOM. When you are below this mass, you have two options:

1) Stick with the MTOM speeds. If you can stop at MTOM from a given V1, you can surely stop from the same speed at a lower mass? Or - to put it another way - would you have a problem with departing the runway at MTOM?? Plus, your 2nd segment climb performance will improve - so there is no problem using the MTOM speeds.

2) Proceed up the table until you hit a temp where your MTOM has reduced to near your actual MTOM. Then go with those figures.

Either way, you'll be safe, given that either your actual temp or mass will be lower than limiting. However, if you do go along with the suggestion to just drop the V1, make damned sure your aircraft doesn't use an improved climb schedule.... or you might get a surprise if you loose one :ugh:

[falconbis]

If Flyp gave you values at max take off weight means that you have no limitation for that ruway up to 1500 ft, if you have no emergency return in the little box means that you can perform that SID.

just go to your AFM and compute your speed like any day .

if you cannot match the climb gradient Flyp will gave you some weight limitation or and emergency return procedure which mean that you CAN take off MTOW but if N-1 you CANNOT remained in the SID as not protected at this mass then follow the emerg return procedure mentionned in Flyp to be safe.

you don t have to use the speed produce by Flyp unless you are at that mass, Flyp gave you your max mass limitation.. if you are lighter you have to use the appropriate speed as long as you are below the limit given by Flyp..

[733driver]

falconbis wrote: if you have no emergency return in the little box means that you can perform that SID.

I am afraid that's not correct. Flygprestanda doesn't take the SID into consideration. No info in the box means straight ahead to 1500', then you are on your own. You have to determine yourself if you can meet the SID climb gradient with one engine out. Flygprestanda does not know which SID you are planning to fly and does not produce SID specific charts as far as I know.

[CL300]

733driver is right, flygprestanda assess ONLY the runway , under different conditions. The code associated with the limitation tells you which limit you reached ( Obstacle, Field , gradient, etc...)
The SID CANNOT be taken into account, the published numbers have to be used whenever you are within 2000 Lbs of the computed MTOW.
For the EFP, Flygprestanda is looking 10 km from DER (sometines 25 km), if you cannot fly straight ahead during an engine failure and maintain terrain clearance ( 35 ft straight, 50 ft in turn), they will provide the alternative path ( EFP).

Only the real manufacturers(or real airlines) are providing ( for a fee) an integrated tool to assess obstacles and path at the end of the SID. Otherwise go to AFM, distant obstacles, get a survey chart, plot with the appropriate formula (90+0,125 d ) etc.... and have fun !!!:hmm:

[falconbis]

firstable, If its to do 1500 ft strait ahead and then you are in your own in IMC in middle off nowhere !! you don t need to spend money on Flyp for that kind of information...:hmm:

733 driver if no ERT in the box and you cannot match Climb G mean that you cannot go.. also, try to fly strait ahead at 1500 ft n-1 taking off 07 or 09 in LBG heading to CDG and see what will happen next !! I don t want to go into a philosophical discussion about Flyp perf but a simple tip:

[/LIST]either you match the climb gradient required by the SID and then you CAN remain N-1 in this SID:O


[/LIST]You CANNOT match the climb gradient so you cannot fly that SID N-1:=


[/LIST]you CANNOT match the climb gradient and Flyp tell you that you can T/O with x mass AND gave you an emergency return procedure, then you can go and Fly the ERT if n-1 before Tosa. That s why you are paying for !!! :rolleyes:

[keepin it in trim]

Flygp meets the regulatory requirement to prove your performance to 1500 ft, nothing more, unless you specifically request it. If you are below the max mass quoted you may use tab data for that weight, as the speeds given by Flyg are for the max performance (or structural, if lower) mass quoted.

It is up to you to calculate if you will still be able to comply with the SID. On that note, it is well worth looking at why the gradient is required. Many SIDs have a gradient for ATC purposes, some (swiss places in general) are for terrain clearance. Logically, if I am OEI on a 2 engine aircraft, unless weather, performance or special circumstances preclude it, I am probably going to return for an overweight landing where I just left. Having of course taken time to suitably prepare, which I will do at an appropriate safe altitude/position.

Where all this gets a little muddy is what you do if you have already turned into the SID when life starts to get interesting, but that's why we get all that extra commanders salary isn't it??!:eek:!

[Empty Cruise]

falconbis,

Thing worth remebering is that most SIDs will turn you at some point. This results in a loss of climb gradient that you have to take into account = lower TOM.

Also, an SID PDGs include the 0.8% increasing obstacle clearance - again, if you don't remeber to remove this, you'll pay in the form of a lower TOM.

At the end of the day, name of the game is lifting max out of any given runway while staying safe and legal. If company A can lift 2000 lbs more out of any given spot than company B (and it is mission-critical, eg A can do it non-stop, B needs a fuelstop), then A gets the job. That's why we use the performance gurus and their tables - not to be safe, but to be safe while making money.

Both methods (perf calcs or "follow SID") can be safe as long as you don't "mix and match", eg take the perf limiting mass from Flygp tables and then follow the SID :ugh: if you loose one.

Thing to remeber with Flygp and other service providers is that their obstacle calculation is performed not only to the point where you achieve 1500 ft, but to a specified distance (usually 25NM from ref zero) or 1500 ft AAL, whichever is later ;) So only a concern if you cannot achieve enroute obstacle clearance in that space.

As for LBG - if you get a product from any service provider that you cannot use (eg no ETP ex LBG), then call them and they will add one for you. They are there for you and will accomodate any reasonable request - if not, time for another service provider :ok:

Keepin it in trim,

Flygp actually give you the performance limiting mass - unlike APG where if performance limiting mass is greater than structural, then they will not show a number greater than structural :rolleyes:. Great for people who don't know the limitations section too well, not so great if you are despatcing with something that will performance limit your aircraft.

Eg APU inop (so bleeds ON takeoff -1800 lbs), low QNH (-500 lbs) and a main gear door missing (-700 lbs), but you're departing from a great airport. Flyp will give you perf limiting mass (say, 85000 lbs, structural limit 78000 lbs, so you can take off @ 78000 lbs). Another provider will give you a table where it just says 78000 lbs, now suddenly you can only lift 75000 lbs :ugh:The providers in question - you know who you are!