Hi guys.

 

I'm running TOPCAT and PFPX together. i'm having trouble understanding the calculations PFPX has thrown at me, also do i bleed off the vapp SPEED before touch down but not below VREF + 5?  here goes...

 

 

** LANDING DATA EGPH 06 **

 

COND:    64635 KG // RWY DRY // +17°C  Q1012  110/08  // LMT: STRUCT

CONFIG:  FLAPS 30 // A/I OFF // A/C ON

SPEEDS:  VREF=148  VAPP=155

ENG OUT: AT 12 DME 'IVG' 108.9 RT TO 'EDN' 341.00 (230 INBD,RT)

 

now is that vapp correct? 155 knots and am i right in thinking i should bleed off that speed untill 153 knots? 148 + 5 

It appears that it incorporated the wind data and used that to determine the correct VAPP. Maintain that speed until the flare. In a perfect world, you'd bleed off down to 148kts and touch down at that speed.

 

 

VREF+5 is really just a guide, not a rule for approaches. It can, and does, change depending on different variables such as wind.

Hi kerlix so i will use the vapp speed PFPX / topcat provide for me? and bleed that off over the threshold to 148 kts?

 

is that VREF = 148 with + 5 added to it yeh?

Examples - 

1. Vref 120kts, Runway 18, wind 180/10. Bug set at 125, touchdown at 125

2. Vref 120kts, Rwy 18, wind 180/20G30. Bug set at 140 (steady headwind = 20, 1/2 of 20 = 10. Gust = 10, so 10 + 10 = additive 20), touchdown at 130 (bleed off the steady headwind additive of 10kts & just carry the gust additive of 10kts to touchdown).

 

 

also do i bleed off the vapp SPEED before touch down but not below VREF + 5?

 

According to 737 FCTM for landing without autothrottle, you maintain any gust correction to touchdown, but bleed off the headwind correction approaching touchdown (pg 1.18)

Touchdown should be at REF plus GUST

spin is that correct calculations that PFPX is giving me?

 

also correct me if am wrong, my app speed will be 155 knots and shortly before touchdown i should bleed off 2 knots, leaving me at 148 + 5 for touchdown?

Since I don't know what your winds are, I can guess that you have a headwind component of 14 knots. There doesn't seem to be any gusts since they are a minimum of 10 knots over the steady state, IIRC.

 

So all of the steady state is bled off during the flare.

Winds -

 

** LANDING DATA EGPH 06 **

 

COND: 64635 KG // RWY DRY // +17°C Q1012 110/08 // LMT: STRUCT

CONFIG: FLAPS 30 // A/I OFF // A/C ON

SPEEDS: VREF=148 VAPP=155

ENG OUT: AT 12 DME 'IVG' 108.9 RT TO 'EDN' 341.00 (230 INBD,RT)

If the winds are 110 at 8 and Vref is 148, then Vapp should just be 153.

Matt you missed something,

 

Runway heading 060

 

Wind direction 110

 

Its not a direct heading its at 110 degrees! 50% for DHW so it can't be half of 8kts?

Matt you missed something,

 

Runway heading 060

 

Wind direction 110

 

Its not a direct heading its at 110 degrees! 50% for DHW so it can't be half of 8kts?

I didn't miss it. I just know that any wind of 10 or less, regardless of direction, is going to have a wind correction of 5.

Not sure why PFPX is off then?

 

I'll just stick with what it gives me lol

 

Another thing after i takeoff i get the flashing A on the MCP i'm i overspeed for something?

 

Gear is up!

 

Flaps 1

 

V2 153 + 20

Flashing A actually means that you have set MCP speed below minimum.

Well it was set at V2 153 per the FMC?