B738 & A320 performance question for pilots

Comhrá

What sort of climb rates are attainable for the B738 & A320-200 under normal operations? Say, a 2 hour flight with average payload & fuel?

I'm guessing they could do 5000 FPM initially up to FL 10 or so?
How does the climb performance pan out up to say, FL 350?

Just curious. I like FSX and a realistic climb profile would be nice to know

LeftBase

tippman1 wrote: »

What sort of climb rates are attainable for the B738 & A320-200 under normal operations? Say, a 2 hour flight with average payload & fuel?

I'm guessing they could do 5000 FPM initially up to FL 10 or so?
How does the climb performance pan out up to say, FL 350?

Just curious. I like FSX and a realistic climb profile would be nice to know

Depends if you want to push the aircraft to the limit or fly the normal operating envelope

It can vary from 2500fpm in the lower levels down to 800fpm or lower at higher levels in normal ops. It can go to 17000fpm in emergencies like GPWS recoveries, but that is in the sim mostly..... A319s can do 14000fpm on normal departures so I'm told .
If you are cruising at FL300 and are cleared to FL320 you may only climb at 500fpm, maybe a little more. On take off and climb out you may do 2500fpm or more if there is terrain on a normal climb.

Climb speed is more the issue really. If you have calm wind or a tailwind you will cover more ground per minute than you would with a headwind and so may not avoid terrain you want to climb out over. Once you are above 10,000' the FMC tells you what what aircraft wants.
In an A320 at my company in the climb it is about 200kts up to 3000', and 250kts up to 10,000'. The aircraft shows you a green dot on the pfd for the best angle of climb(Vx)(most amount of altitude in the shortest ground distance). Vy is the best rate of climb(most amount of altitude in least amount of time). This speed is not on the pfd but is between the econ speed(best cost index speed) and green dot. It is somewhere close to the published turbulence penetration speed as a general rule of thumb.

After 10,000' let the FMC decide what it wants to do. That speed could be between 250kts and 330kts depending on what the conditions are.

smurfjed

The standard Airbus takeoff chart for single runways shows takeoff data columns based on -10/0/+10kts of wind. Any obstacles are calculated based on that wind value and the weights / V-speeds are optimised for the revised obstacle distance. This is standard for all optimised software. However I am interested in where you get the obstacle data that allows you to determine if it is better to use VX or VY speeds based on all engine performance?

Our standard A320 departure profile is V2+10 until acceleration height, then 250 its until 10,000 feet followed by FMS speeds based on the input of the crew.

This speed is not on the pfd but is between the econ speed(best cost index speed) and green dot.

As ECON speed is based on costs and is therefore variable, i would have thought that you would be better off if you used Green Dot and LRC speeds?

It can go to 17000fpm in emergencies like GPWS recoveries, but that is in the sim mostly..... A319s can do 14000fpm on normal departures so I'm told

With or without the wings staying attached?

Disclaimer, I have never flown the A320, but we operate about 50 of them, so its easy to find someone to discuss the aircraft's performance with

smurfjed

LeftBase

smurfjed wrote: »

As ECON speed is based on costs and is therefore variable, i would have thought that you would be better off if you used Green Dot and LRC speeds?

Even if the climb ECON speed changed, Vy should still be in between Econ and Green Dot somewhere. It just may be closer to one than the other meaning the selection of climb speed may be influenced. That's assuming there are no mountains or airspace/traffic restrictions.

With or without the wings staying attached?

That was meant as a comment in jest. There are many exaggerations about how well the A319 performs in relation to the A320/321.:)

smurfjed

Vy should still be in between Econ and Green Dot somewhere

Not if the fuel cost is cheap, so the logic dictates that it makes more sense to climb fast.

Where are you getting the obstacle information from that allows you to decide if you want to use VX or VY?

Ignoring the 19000 fpm for the A319, is the 14000 fpm for the A320 TCAS realistic? What ROD do you achieve in an emergency descent?


smurfjed

LeftBase

smurfjed wrote: »

Not if the fuel cost is cheap, so the logic dictates that it makes more sense to climb fast.

Where are you getting the obstacle information from that allows you to decide if you want to use VX or VY?

Ignoring the 19000 fpm for the A319, is the 14000 fpm for the A320 TCAS realistic? What ROD do you achieve in an emergency descent?


smurfjed

Ah but the fuel cost is rarely cheap in Europe!

I'm not sure if I'm picking up your question wrong, but obstacles on departure would(or should be published on the charts).

The 14000fpm as I said was in the sim, and we all know crazy **** happens in the sim when you have a reset button!
ROD in an emergency descent depends really. If you have an explosive decompression at FL300 you don't want to descend too fast(or deploy airbrakes/gear to avoid buffeting) incase you have airframe damage. If the masks are donned and the passengers have their oxygen supply running it is no longer an emergency and is a time limited situation. A ROD of 1500-1800fpm in this situation would suffice.

If you have no oxygen supply for whatever reason and must reach 10,000' asap and do not suspect structural damage then select 10,000' alt, thrust idle, MMO/VMO, airbrakes deployed.(select a heading off your airway also, although the CAA don't seem to like that). You could be descending at 5000-6000fpm maybe.

smurfjed

We pay 8 cents per litre for car fuel, Jet A1 is about the same, so this really messes up Cost Index calculations. I was hoping that you would pick me up about the use of LRC in climb, but you didn't.

You introduced the use of VX/VY into this discussion, so I'm interested to learn how you actually use these speeds rather than your canned profile speeds. As for the obstacles on the charts, the airbus takeoff chart states the number of obstacles used in the calculation, it doesn't show the distance/height nor gradient to these obstacles, so how do you decide when you are going to use VX/VY?

As for the 14,000 fpm and 17,000 fpm, lets accept that these are not realistic.

The great thing about aviation is that there are many ways to do things, so we live in a world of constant learning, thats what makes this type of life so exciting

smurfjed

smurfjed

We pay 8 cents per litre for car fuel, Jet A1 is about the same, so this really messes up Cost Index calculations. I was hoping that you would pick me up about the use of LRC in climb, but you didn't.

You introduced the use of VX/VY into this discussion, so I'm interested to learn how you actually use these speeds rather than your canned profile speeds. As for the obstacles on the charts, the airbus takeoff chart states the number of obstacles used in the calculation, it doesn't show the distance/height nor gradient to these obstacles, so how do you decide when you are going to use VX/VY?

As for the 14,000 fpm and 17,000 fpm, lets accept that these are not realistic.

The great thing about aviation is that there are many ways to do things, so we live in a world of constant learning, thats what makes this type of life so exciting

smurfjed

LeftBase

smurfjed wrote: »

We pay 8 cents per litre for car fuel, Jet A1 is about the same, so this really messes up Cost Index calculations. I was hoping that you would pick me up about the use of LRC in climb, but you didn't.

It's 50p/l at Gatwick afaik.

You introduced the use of VX/VY into this discussion, so I'm interested to learn how you actually use these speeds rather than your canned profile speeds. As for the obstacles on the charts, the airbus takeoff chart states the number of obstacles used in the calculation, it doesn't show the distance/height nor gradient to these obstacles, so how do you decide when you are going to use VX/VY?

Actually I introduced the speeds as a way of explaining what the max climb rates for an A320 were to the OP. And how we obtain max altitude for distance(x) or time(y). I was talking more about when you would use them viewing a situation yourself while planning. For example sitting on a runway with a 1500ft peak 2 miles off the end and saying...well I'll need a climb angle good enough to get over that. Econ climb wont give me that and either would Vy so I'll have to go with Vx even though it will burn more fuel and take more time(assuming you do not go around the peak). I was taking the FMC out of the equation altogether. He said it was in relation to FSX where you do not have an FMC(unless they have them now).
When I said charts I was refering to the actual VFR chart/SID for the area. I should have clarified that

As for the 14,000 fpm and 17,000 fpm, lets accept that these are not realistic.

I was simpley giving an upper end for the max ridiculous climb rate you could get away with for a short time...albeit in the sim!

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