PMDG 739 - Is this realistic ?

[pmplayer 9,817]

Hi guys,

The last days i did 2 flights with the PMDG 737-900 using a example like this:

Staring with 158000lbs TOW took me with AP on and LNAV/VNAV about 190nm to my set altitude of 33,000 feet. This 33000feet was proposed by the FMC.

Is this near real life, I thought it should be quicker what are your experiences ?

 

cheers 😉

[Paladin2005 451]

Also depends on the CI. The higher the CI, the faster the speed, the slower the climb. Needs longer to reach cruise alt.

Correct me if im wrong.

[F737MAX 5,938]

From my very amateur perspective, I say that doesn't feel right. Normally, would expect a climb in a modern airliner to take around 100nm to reach 33,000 feet.

Are you sure you selected the desired TOW and inputted this correctly into the FMC? 158,000 lbs is heavy, but 16,000 lbs under MTOW.

What Cost Index value did you enter into the FMC?

Did you have a strong tailwind on climb?

Did you see the engines operating a higher than expected numbers during climb and cruise?

Are you certain that slats, flaps, spoiler, gear are all correctly and completely stowed?

What was the outside air temperature? And did it drop as per expectations in line with the gain in altitude?

[pmplayer 9,817]

3 minutes ago, F737MAX said:

From my very amateur perspective, I say that doesn't feel right. Normally, would expect a climb in a modern airliner to take around 100nm to reach 33,000 feet.

Are you sure you selected the desired TOW and inputted this correctly into the FMC? 158,000 lbs is heavy, but 16,000 lbs under MTOW.

What Cost Index value did you enter into the FMC?

Did you have a strong tailwind on climb?

Did you see the engines operating a higher than expected numbers during climb and cruise?

Are you certain that slats, flaps, spoiler, gear are all correctly and completely stowed?

What was the outside air temperature? And did it drop as per expectations in line with the gain in altitude?

Are you sure you selected the desired TOW and inputted this correctly into the FMC? 158,000 lbs is heavy, but 16,000 lbs under MTOW. --   Yes

What Cost Index value did you enter into the FMC?--   52

Did you have a strong tailwind on climb?--   5kts

Did you see the engines operating a higher than expected numbers during climb and cruise?--   I didn`t watched this realy..

Are you certain that slats, flaps, spoiler, gear are all correctly and completely stowed?--   Yes

What was the outside air temperature? And did it drop as per expectations in line with the gain in altitude?--   Not shure , unfortunately I didn't pay attention to that..

 

cheers 😉

[Bobsk8 13,056]

Might want to ask this on the PMDG 737 forum. They have a real 737 airline pilot there that can probably give you an answer.

[Antipodeslonghaul 84]

Interesting indeed. What was it about 28 minutes (circa 400 kts av gs)? I'm just simming now and opened FlightRadar24, used filter for 737-900, looking at UAL1984 EWR-SDQ. Now that's only about a 3:15 flight, so maybe quite a bit lighter, but let's see. Right now passing 20,000, 10 minutes, and about 50 nm.

Edit: Of course not all will climb in the same manner SID's, ATC limitations etc. This one should be reaching FL330 any moment now. Looks like it took them about 22 minutes and about 130 nm.

Edited September 10, 2023 by Antipodeslonghaul

[Fiorentoni 4,582]

26 minutes ago, pmplayer said:

What Cost Index value did you enter into the FMC?--   52

That's a very high cost index for a 737, meaning you'll have a very high speed during climb and in consequence a much lower climb rate. Combined with the heavy TOW that means you'll be climbing for a long time.

Edited September 10, 2023 by Fiorentoni

[Stearmandriver 2,343]

This is an impossible question to answer, given that none of us know the conditions of your climb.  There are so many variables here.

What I can tell you is that, if operated like the real airplane, the PMDG -900 climbs like the real airplane.  There's nothing wrong with how the sim version performs, if that's what you're asking 

[pmplayer 9,817]

14 minutes ago, Fiorentoni said:

That's a very high cost index for a 737, meaning you'll have a very high speed during climb and in consequence a much lower climb rate. Combined with the heavy TOW that means you'll be climbing for a long time.

This was the simbrief setting..

And i think it is not to high - what is usual be used ?

cheers 😉

[F737MAX 5,938]

1 minute ago, pmplayer said:

And i think it is not to high - what is usual be used ?

See these:

https://costindex-index.fandom.com/wiki/Different_Cost_indexes_from_ALOT_of_airlines

[Stearmandriver 2,343]

35 minutes ago, pmplayer said:

This was the simbrief setting..

And i think it is not to high - what is usual be used ?

cheers 😉

15 is our default, but ETOPS flights are usually planned at 60 (as are some transcons.). I've seen 99 when running late.

For your climb, a bigger difference would be made by your takeoff thrust setting - not because of the takeoff itself but because, if you significantly reduce takeoff thrust, the FMC will schedule a reduced climb thrust for the first portion of your climb.  If you're climbing in a thrust rating of CLB-1 or 2, instead of just CLB, that'll be a big difference.

[pmplayer 9,817]

22 minutes ago, Stearmandriver said:

15 is our default, but ETOPS flights are usually planned at 60 (as are some transcons.). I've seen 99 when running late.

For your climb, a bigger difference would be made by your takeoff thrust setting - not because of the takeoff itself but because, if you significantly reduce takeoff thrust, the FMC will schedule a reduced climb thrust for the first portion of your climb.  If you're climbing in a thrust rating of CLB-1 or 2, instead of just CLB, that'll be a big difference.

Thank you, will try that..

cheers 😉

[pmplayer 9,817]

Guys, thank you all for the tipps !

I tried my last flight again with all the same TOW ect.,ect. only using CI 6 and CLB 1 Power and got my 33000feet at 130nm from before 190nm - so this looks realistc to me.

And if i understand this right and i use CLB 2 it should save some more NM but however looks pretty fine now.. 👍

cheers 😉

[Bobsk8 13,056]

2 hours ago, pmplayer said:

Thank you, will try that..

cheers 😉

An airline 737 first officer answered your question on the PMDG forum. 

[F737MAX 5,938]

26 minutes ago, pmplayer said:

And if i understand this right and i use CLB 2 it should save some more NM

It's the opposite to that.

Less thrust = longer climb.

 

Quote

CLB-1 indicates that the autothrottle is commanding a reduced thrust climb power (reduces N1 by approx 3% = 10% thrust reduction).

CLB-2 is a reduction of a further 10% ie 20% total.

The reduced climb thrust setting gradually increases to full climb power by 15,000ft.

Source: http://www.b737.org.uk/fmc.htm