PMDG 737 Discussion

Yes, you got it, 2500-3000 fpm. And for derate/flex settings I use this calculator:

Virtual Performance Tool

It’s for free now but they will change to a subscription model later on. You can just try it. They have only a calculator for 737-800 but for derate/flex it works fine. Then you can use V-speeds that are calculated by your FMS. I hope this calculation comes with the EFB that PMDG are working on. Fenix A320 got it and it’s great.

I’ll check it out too. Thanks a bunch for the help! :beers:

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hopefully this stops a lot of whinging and moaning from certain people.

Whatever… just release the ■■■■ VNAV/LNAV update… Guessing we will never see that though.

That only took about 25 minutes to return to complaining, I’m shocked. :rofl:

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It’s in the works and the most recent update includes some background work for it.

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Yeah got the update. There’s just one problem…
If I try to install the product as admin, it won’t even detect my FS installation. So I have to do that with my normal user account.
Then Ops Center detects that there is an update available. But to install it, I have to restart Ops Center with admin privileges, leading to the point above.
So… No update for me. :slight_smile:

Real world pilots DO use VNAV a lot for departure in real life. Just because you’re told by someone that they - probably by their company SOP - don’t use it doesn’t mean that nobody uses it.

In this case though it’s not the VNAV to blame. The flight computer will aim for around V2+20 for (first and) second segment climb regardless of the pitch mode. If you have more thrust than you need for your actual takeoff weight this will result in high pitch commands in order to maintain that speed.

You can also end up in the same situation using bad rotation technique on takeoff or of course with sudden headwind component increase on departure.

There is a limitation of 20 degrees maximum pitch for takeoff - I believe it comes from Boeing since all the SOPs I’ve flown had it - but I’m pretty sure it is not built in in the autoflight logic so you can encounter higher F/D pitch commands.

The 737-700 is a beast when it comes to power/weight ratio so calculating for the proprer T/O N1 is key - especially with low(er) weights.

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We use VNAV as soon as the flaps are up.

Using VS during climbs is bad piloting. In fact, in some airlines climbing in V/S is completely prohibited except for the last 3000, 2000 and 1000 feet to level off, where we select it to 3000fpm, 2000fpm and 1000fpm respectively ONLY IF the vertical speed exceeds those values at that time. This is to prevent level busting and to prevent triggering other peoples’ TCAS.
Any other time during climbs you must use VNAV (preferably) or LVL CHG making sure you will not bust an altitude restriction (LVL CHG ignores legs altitude constraints that VNAV respects).

In the 737, after take off the airplane will effectively be in LVL CHG. All you have to do is select BUG UP according to your noise abatement procedure (1000ft AAL for NADP2 and 3000ft AAL for NADP1). Then retract flaps per schedule. Once you have flaps up no lights you can select VNAV.

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That is correct. We never go above 20ºNUP when manual flying in normal operation. If you’ve calculated your take off performance correctly and took off with the appropriate thrust rating, you shouldn’t need 20ºNUP to maintain between V2 and V2+20 (which is the range of speeds that the flight director is pitching for). Once we select the autopilot (usually at 1000ft AAL), it’s ok for it to pitch above 20ºNUP.

The takeoff in the 737 is very simple. First you pitch up to 15º. Once you retract the landing gear and the flight director starts giving coherent indications, you will follow flight director limiting yourself to 20ºNUP. At 1000ft engage the autopilot if you want and let it do its thing. That’s all.

Regarding VS on climbs. Don’t. You’ve been given bad advice there. We almost never use VS during climbs. It’s bad piloting.

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To the RL 737 drivers here - the conversation on how you climb is fascinating and very useful. If I could ask a related question - how do you typically descend? VNAV, LVL CNG or dial it in with VS? I’m struggling with the calculated TOD the FMC shows. It seems that if I use it, I’m required to go with a very fast rate of descent (around 4,000 FPM), with speed brakes needed to keep the speed under control. Do you guys typically get to TOD, go to idle and maintain that most / all of the way down until you get closer to the airport? What’s considered to be an excessive rate of descent?
Sorry for all the questions, I know there are many variables in play with something like this.

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We can use all modes during descent but any RL pilot will always choose the best level of automation possible, so 90% of the time we will descend in VNAV PTH. You shouldn’t need speedbrakes. If you do, then you’re doing something wrong. It’s very unlikely that speedbrakes will be used above FL100 in real operations. In fact, it’s very “un-elegant” to do so. The only reason to use them is when you’re speed restricted and high. If you’re not speed restricted, you should just descend at a faster speed before going for the speedbrakes.

What normally happens is that we will be directed to descent a bit earlier than TOD. When this happens, we select the cleared level in the MCP and while still in VNAV, we will press ALT INTV (or Descend Now in the FMC). The airplane will start descending at 1000fpm until it catches the VNAV PTH. When it does, it will command IDLE and descend along the path. This path is calculated at the ECON or the selected speed you can see in the descent page in the FMC. If for any reason (winds), the geometry of the path does not result in the desired speed, you can update the path by redirecting yourself to the current point you’re flying to. If the winds are so different that you end up being high, simply type in a new speed in the descent page.

In high levels we will likely only use VS-500fpm when we’re instructed to descend a lot earlier than TOD. ATC doesn’t like it when we do this, so shortly after they will say something like “Descend FLXXX 1500fpm or greater”. Then we will use VS-1500. We wouldn’t use LVL CHG or VNAV SPD descent in that case because it would result in a descent rate higher than we want to (we don’t like to descend early… German ATC). Once we get “free rate” by ATC we will again use VS-500 or VS-1000 or simply go back to VNAV. The airplane will catch the original path.

The only time we will use VS is to fine tune the last stages of descent to catch the glideslope when vectored. We avoid levelling off at all cost. We want to keep the airplane descending on CDAs (or the airline could pay a fine). So if they’re vectoring us and we’ll end up flying more miles than we planed for, then we’d be low. We’ll slow down and use VS to avoid getting even lower.

Remember on climbs VS mode is a big no… unless at 3, 2 and 1 to go ONLY IF your VS exceeds 3000, 2000 and 1000fpm.

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Sorry for misleading you here, I use LVL CHG mode, though I didn’t know that VNAV should be engaged when flaps are up. The presence of real 737 pilots here and their knowledge is absolutely godsend. In the beginning I followed this pilot (he’s also a member of the PMDG team). I guess he also shows the calculation for derated TO there:

(2) PMDG 737 for MSFS - Tutorials - YouTube

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No worries at all. We’re all learning (most of us anyway) and I believe there’s a place in the process for even incorrect information as it sometimes is the quickest path to the truth! :wink:

And yes on the YouTube link. I’m a subscriber to 737NG Driver and really enjoy his tutorials.

And FormerSnail is a great addition to this community as are all the RL pilots who help us with their knowledge and wisdom.

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Did you ensure everything was setup properly? Proper ILS frequency and correct flight plan with the appropriate approach selected? There have been times when I would have a let say ILS 16L approach planned with all frequencies tuned in and all but would accidently select 16R on the FMC. It seems like KDEN 16L AND 16R and pretty well spaced. Perhaps maybe you didn’t notice you lined up with 16L and the aircraft didn’t capture the localizer at all?

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Yeah not sure now. Fairly certain it was all set up, but I haven’t had the issue again either.

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Where can we read in detail what has been updated?

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[24JUN22] Happy Friday - Update Released for PMDG 737-700 for MSFS. - PMDG Simulations

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So…how many hours have we all got clocked up so far?

I’ve just ticked over 30, been flying exclusively in Australia and picked up a few nice sceneries with the current ORBX 40% off sale (YBMK, YAYE, YPAD).

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I’ve just bought NZWN from Flightbeam, there is also a summer sale in their shop, so I’m eager to fly NZAA - NZWN in 737. But first I must finish my flight KCLT - KBOS in Fenix A320. And how many hours? Many :sweat_smile:

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