But we might hope for that feature in PFPX http://www.flightsimsoft.com/pfpx/

 

No, we might not. PFPX will not be able to calculate TO and landing performance (it will be able to integrate with TOPCAT though)

 

Surprising...

Are VR and V2 calculations also not real, but a PMDG courtesy?

 

They are real all right, but not runway dependent.

What the FMC will give you are V speeds for so-called "balanced runway".

 

Balanced runway means, that V1 is set so that you will use the same amount of space for go and for stop situation, leading to a slightly sub-optimal performance.

You can use these speeds as long as the actual weather-corrected runway length is longer than required balanced field length. (And no obstacles are present) If it is shorter, you might not be able to use it, unless you have more data in form of Runway Analysis spaghetti charts or performance program akin to Topcat.

Thanks, Peter.

Regarding these GOL flights SBRJ-SBSP, what would be approx. correct/typical V1s for the SBRJ runways

- no wind

- 10 kn head wind

- wet runway, no wind?

This is difficult. You would need some kind of GOL-specific performance manual, their own runway analysis book or performance program, whichever they use.

 

Best I can do is steel brakes, no SFP 737.

First case 737-700, 120 pax+bags, 4tonnes of fuel on take-off, assuming about 2t reserve, TOW of 53.650

Unfortunately I can only do 22K engines, not 24K PMDG has. Conditions are ISA day +15C, Q1013. No derate, optimum flaps, no bleed, no antiice. SBRJ RW02R.

Format is:

-case: MTOW, speeds V1/Vr/V2 (for 53650, no AST), max permissible AST

-no wind: 57238, 113/113/119, 35

-10kt head: 59307, 113/113/119, 40

-wet: 54608, 107/128/128, N/A

 

737-800, 140pax+bags, 4,2t of fuel, TOW 59400

-no wind: 58313 - - -

-10kts head: 60139, 133/133/133, N/A

-wet: 55933 - - -

 

Every one of these take-offs is with flaps 25.

What you can see - basic 737-800 is useless here. It can only take about one tonne more, but weighs about 3 tonnes more empty. That makes 2 tonnes less available payload, and I have not slammed 24Ks on the 700 yet. It makes it quite obvious why GOL needed SFP then.

 

To read more into this, I would need to make a full on analysis using FPPM, and see where all the variables that go into V-speed consideration are.

Thanx Fabo.

 

If 'wet' reduces the MTOW about 3 tons, how do airlines handle this in daily operations.

Can they really plan for the higher 'dry' or 'head wind' weights, if showers are always possible?

This is not that much a factor for most 737 flights. Usually you just use a lower derate/AST (or as some airlines do, no derate/AST at all).

 

It CAN get problematic on short runways though. You have several options than, two major ones being A. Load less fuel, fly to a close airport with long runway, and fuel there, or B. leave some 30 people on ground or load less cargo. Both can get pretty expensive though, so it is best for them not to happen.

 

As for showers being 'always' possible, well, technically, that is true. But we have stuff like forecasts, seasonal weather averages etc. so you can both plan ahead and use smaller planes for rain season or substitute better performing type (like sending 757 in instead of 737-900). Or, if feasible, you can move passengers to a nearby airport which you can use, this was very common in winter in LZZI before ILS was put in, oftentimes the inbound evening flight could not get in, so the airline would organize transfer to LZIB for passengers.

Ok, for SBRJ SBGL is close by... and GOL fly there, too.