High winds takeoff

[Driver170 42]

On navigraph STAR charts for engine failure you have a box some say NON STD and STD for engine failure what are these?

 

Also MNM CLIMB GRADIENT 6.6 % to 5000 what is the calculation for that guys?

[Vargveum 53]

See SID 25L/C MARUN 3F/3J TOBAK 4f/4J: Climb gradient 12 % to D8.4 FFM.

 

This means you have to climb 12 % in altitude for the distance of 8.4 nautical miles from FFM. 

 

12 % of 8.4 is 1 nautical mile. 1 NM = 6074 ft.

 

If you have a ground speed of say 180 knots on climb out you cover 8.4 nautical miles in 2.8 minutes

 

In that time you need to climb 1 mile. Again 1 NM = 6074 ft.

 

6074 ft / 2.8 min = 2169 ft / min.

 

So basically 180 knots ground speed on climbout requires rate of climb of more than 2169 ft/min to make the profile set in the SID. 

 

 

The easy way to calculate it in the cockpit is to multiply your ground speed with the % gradient:

 

12 % gradient x GS180 = 2160 ft/min

 

7 % gradient x GS180 = 1260 ft/min

 

5 % gradient x GS160 = 800 ft/min

[Driver170 42]

Where did you get that 2.8 min from?

 

Thanks for the sum dude :)

[Captain Kevin 586]

Interesting. Learned something new. Thank you.

[Vargveum 53]

 

 

Where did you get that 2.8 min from?

 

If you have a ground speed of say 180 knots on climb out you cover 8.4 nautical miles in 2.8 minutes. Now, the 180 knots is just an example. 

[Driver170 42]

Yeh but how do you do the maths 180 kts in 8.4 nm ?

 

My maths sucks dude being honest here lol

[Captain Kevin 586]

Yeh but how do you do the maths 180 kts in 8.4 nm ?

 

My maths sucks dude being honest here lol

Knots is simply nautical miles per hour, so you take 8.4, divide it by 180 knots, and that gives you the time to travel that distance in hours. Multiply by 60 and you get 2.8 minutes.

[Driver170 42]

But do we actually need to do this for the 737 as the FMC will do this when in VNAV?

 

 

How about 7.4 % for 4500 i got 2,300 fpm and climbing out at 168 knots?

[Vargveum 53]

 

 

How about 7.4 % for 4500 i got 2,300 fpm and climbing out at 168 knots?

 

Then it is as follows: (7.4 x 168) ft/min = 1243,2 ft / min required. So you are good to go.  ^_^

 

Remember every time you get a climb gradient, just multiply that factor to your ground speed. That will give you your required rate of climb.

[Driver170 42]

Is this something real pilots do even if they are using a sid and VNAV?

[Vargveum 53]

VNAV doesn't do you much good if the aircraft doesn't have the performance to perform the SID as published. 1200 ft/min rate of climb isn't a problem in a 737 though. 

[Spin737 102]

Is this something real pilots do even if they are using a sid and VNAV?

Two things:

 

1. VNAV has ZERO effect on climb performance over any other mode.
2. Most airlines have engineering departments or a vendor that provides data that takes all of the climb performance parameters in to account. You only need to know the weather and runway conditions and the data will tell you what weight you can take off with with various flap settings. Some companies break it down by runway weight and climb weight and you choose the lower of the two.

Made up Eg. RWY 21, temp 25C, dry runway - you can takeoff at 169,000lbs. Are you below that? Great. Go.

[Driver170 42]

Ahh i see so i won't need to do sums then what we've been discussing us that correct?

[Vargveum 53]

Ahh i see so i won't need to do sums then what we've been discussing us that correct?

 

Hehe... well, do you have an airline feeding you the performance data? ;) Seriously, it's all a matter of how far you want to go with this in your flight sim hobby. Maybe not that much in the beginning, then later you might want to go deeper and learn more about the technicalities and details.  

 

However, I think you will be fine without doing the the calculations, buddy.

[Spin737 102]

Ahh i see so i won't need to do sums then what we've been discussing us that correct?

If you didn't have company-provided you would. But for the ease of day-to-day operations, no you don't do this in airline world.

 

Airlines typically know what places they fly to and will have everything ready to go for the crews. The dispatcher would look at the weather and the runway and say, "Flight 590, you're okay to fly at 170,00 pounds from runway 21 at International Regional Express Airport."

 

You'd take a look at the temps and weather once you get your final weights to make sure you're still good to go at 170,000.