PMDG 737 Discussion (PC Version) (Part 1)

[JetWash1023]

@FormerSnail5736

Well, we do use V/S sometimes approaching any level off (both climbing and descending). We do it to avoid triggering other people’s TCAS and to smoothen the level off. It’s in our SOPs.

I did already mention that.

I don’t get this ‘smoothen the level off’ thing though. The capture logic in VNAV and LVL CHG does a perfectly good job of achieving nice level-offs, a passenger would never be able to tell the difference. I can understand using V/S if you are only given a 1,000ft climb or descent, descending in a hold, capturing a glideslope from above (generally SOP), in a busy environment (like the London TMA) when there’s an obvious potential traffic confliction or a non-precision approach (although again, much better options are available). Beyond that it’s probably the autopilot mode most likely to get you into trouble, and in my experience generally used by people who don’t understand how to use VNAV.

It’s obviously SOP in some airlines but I’ve never heard of this 3-2-1 thing before. I don’t get why it would be necessary, and it’s not something I can say I’ve ever read in a Boeing FCTM.

On that note, for anyone interested the ‘Flight Crew Training Manual (FCTM) is an extremely useful manual, provided by Boeing for each family of aircraft. There is no operator input to it, and it covers all the ‘how’s’ of how Boeing recommend their aircraft are operated. This version is old (2007) but it would be more than sufficient to help you understand every aspect of the PMDG aircraft.

https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.395.536&rep=rep1&type=pdf#page139

[SavvySigma]

@GamingCat2130

That is up to me how I learn fly, I prefer learn flying by having the great honour of real Airbus and Boeing pilots showing inside the cockpit how things are really done while writing down procedures and important things in my sketchbooks, not by reading some heavily simplified and modified PDFs

You mean that same “simplified” documentation that PMDG provided, which actually had the answers you required 1st time around?

Doubling-down on laziness is just going to make people here want to help you far less, if at all.

[BlackSanta512]

Perfect timing. I keep doing something wrong on my descents and have to correct late to hit the G/S using VNAV. Thanks for this!

[Redeyesjm]

@LameLefty

You know, if you would spend a tenth of the time reading the documentation as you do obsessing about your perceived deficiencies in the textures, you wouldn’t have to ask this kind of stuff.

Just sayin’ …

Hi. I think GamingCat2130 is mis-understood re: texture comments. I’ve read this entire thread from the very begining (wildly enjoyable) and I’ve found his comments interesting, especially when taking in to account their background. It’s obvious the person enjoys flying in the sim. There is nothing wrong (IMO) with seeing these things or automatically being drawn to them. I think it would be fine to tell PMDG about them and offer any help. That does not include uploading all the fixes due to potential legal concerns. If PMDG is interested, they can make contact. It’s up to them. Anyway, just my 2cents. Thanks.
–Redeye

[TFEV1909]

@JetWash1023

I don’t get this ‘smoothen the level off’ thing though. The capture logic in VNAV and LVL CHG does a perfectly good job of achieving nice level-offs

From what I understood from the the 737NGDriver the 3 2 1 rule is primarily used to prevent false TCAS warnings. I am in no position to judge the validity of that reason, but it is funny to see an apparently very experienced pilot explained this 3 2 1 rule and somebody else saying it is more or less nonsense

I haven’t read your bio, but out of curiosity, do you fly the 737 as well?

Interesting discussions!

[FormerSnail5736]

@JetWash1023

I don’t get this ‘smoothen the level off’ thing though. The capture logic in VNAV and LVL CHG does a perfectly good job of achieving nice level-offs, a passenger would never be able to tell the difference.

I’m not talking about levelling off at FL400 where the airplane barely climbs. This is an issue with low stop altitudes on departures where the airplane can carry over 3000fpm and you could bust a level by a couple hundred feet. I’ve seen it happen. ALT ACQ is not perfect. But like I said, the main purpose of this is to avoid triggering other airplanes’ TCAS based on closure rate. TCAS does not know where the other airplanes will level off.

I know this is SOPs and you wouldn’t find it in a vanilla FCTM or FCOM. In my previous airline we didn’t do it as per SOPs but some pilots did do it anyway. In my current airline this is SOP and it’s written. It’s a pretty large airline with a whole department dedicated to these things so I’m sure they have valid reasons. Airlines and authorities define KORAs (Key Operational Risk Areas). There’s your level busts, your runways excursions and what not. Based on the current KORAs, TEM strategies are developed to mitigate these risks. Then we observe a change in statistics. When you look at the numbers in large sample statistics, these little procedures usually have a very positive impact. If they didn’t have a positive impact, then the procedure would not be rolled out to main fleet. With the numbers in front there’s really no point in saying that this or that procedure is useless.

[JetWash1023]

@TFEV1909 I have about 8,000hrs (combined) on it in both seats, and now fly a widebody. I’m not saying it’s nonsense, just that it’s not an SOP I’ve heard of before. Just to be clear, I’m not saying that the use
of V/S where appropriate is wrong, particularly in busy airspace with high rates of climb and descent and potential traffic but that comes down to airmanship. This is the first time I’ve ever heard of it being mandated. Perhaps it’s commonplace and it just so happens that the airlines I’ve flown for don’t do it.

@FormerSnail5736 Again, I didn’t say it’s useless, just that I’m surprised it’s an actual SOP as it’s not how Boeing suggest the jet is flown. Personally, I’ve never seen an aircraft shoot through a level in 13,000hrs of flying (although I’m not saying it can’t happen). Like you said, it’d be interesting to see how often it occurs because not only has it never happened to me, I’ve never heard of it happening to anyone else. In looking at what is the bigger threat however, perhaps relentlessly changing autopilot modes (particularly to a lower level of automation) seems to me to be where the more significant threat lies, particularly on RNAV arrivals with complex step descents.

Perhaps it’s a specific 737 issue, I don’t know. It’d be interesting to know form guys & girls that fly other Boeing types if it’s an SOP for them too.

[Masklin1574]

Speak to air traffic controllers in busy airspace, they’ll likely have seen level busts (for various reasons) more than once.

Sensible mitigations, whether that be for preventing spurious TCAS alerts or just plain busting, are to be welcomed.

[GamingCat2130]

The FMC seems to be unstable. I was doing the tutorial flight two times, and it always crashed two times on this page:

To be more specific, when finishing entering the PMDG tutorial PDF flight plan KPDX MINNE5 FAMUK Q3 FOWND MLBEC BDEGA3 and ILS28R to KSFO.
Trying to enter the last entries FOWNED MLBEC … brings the sim to a stuttering crackling end back to the desktop.

The second problem is, the airplane always loads with both hydraulic systems with too low hydraulics fluid whenever random failures, or maintenance base failures are activated in the FMC:

But I don´t want to have realistic failures disabled!
No matter how often the maintenance is done, and all technical errors are cleared in the FMC - whenever the next flight is choosen it always starts with a hydraulic failure.
But luckily the 737 is equipped with wires and pulleys so having no hydraulics should not be such a big deal…

edit:
Aha that happens on other versions of this plane too:

HYD fluid System A refill - PMDG Simulations

By the way now I understand why all Boeings MUST be equipped with an ECAM till the end of 2022.
When there are system failures appearing (and I love that because that makes the flights really interesting, one has to switch off overheating pumps and take care of the machine and this and that…) - but in many cases I simple don´t know what failure it is.
In the Airbus there is an ECAM message saying exactly what´s wrong, and in the Boeing… there is… an illuminated master caution button.
(Of course when going in the FMC maintenance page one can read what failure it is - but what does a real pilot do when a failure occurs? Just a master caution button and some absolute basic announciator panel having a light bulb behind pre-defined words like “FLT CTR” or “ELEC”, but nothing else and no detailled informations.)

[Masklin1574]

p.s. UK and Eurocontrol publish the following (and the FAA similar) so I’m not surprised some airlines have such procedures as mentioned in SOPs…

UK…

3.2.2.3 Maximum Rates of Climb and Descent

3.2.2.3.1 In order to ensure the credible interaction of Airborne Collision Avoidance Systems and ground based safety nets, other than aircraft in emergency and certain specific conditions for military aircraft (as detailed in Military AlP and MAA Regulatory Publication RA 3000 Series), all aircraft when operating under normal circumstances, when inside Controlled Airspace within the London and Scottish FIRs/URs should not operate with a climb or descent rate exceeding 8000 FT per minute. Aircraft when first approaching a cleared flight level and/or when changing flight level in Controlled Airspace should ensure that the vertical closure speed is not excessive. It is considered that, with about 1500 FT
to go to a cleared level, vertical speed should be reduced to a maximum of 1500 FT per minute and ideally to between 1000 FT per minute and 500 FT per minute. Pilots should
ensure that the aircraft neither undershoots nor overshoots the cleared level by more than 150 FT, manually overriding if necessary.

Eurocontrol…

Rate of climb within last 1000 ft before cleared level

What we have been informed

In order to reduce the risk of Airborne Collision Avoidance System (ACAS)/TCAS Resolution Advisories (RAs) which are subsequently shown to have been operationally unnecessary - so called “nuisance” RAs - many operators have standard operating procedures requiring the pilots to reduce rate of climb/descent to less than 1500 ft/min when in Reduced Vertical Separation Minima (RVSM) airspace or within the last 1000 ft before cleared level;

Some operators have expressed concern that when AC controllers specify a rate of climb or descent, they expect the pilots to maintain the given rate until intercepting altitude;

What are the facts and rules?

RAs could occur when aircraft are in close proximity and the vertical speed of closure, which may be the sum of the vertical speeds of both aircraft or the vertical speed of just one aircraft, exceeds 1500 ft/min; Flight Crews can reduce the likelihood of an RA by confining vertical speeds to less than 1000 ft/min, and ideally between 500 and 1000 ft/min, within the last 1000 ft before reaching assigned level. Many national authorities have issued recommendations to this effect within their flight rules and procedures;

• ATC may request different rates of climb or descent at any time for the purpose of maintaining separation of aircraft. In such cases, these rates shall be strictly complied with. Failure to do so could result in a potentially serious loss of separation. It should not be supposed that there will ‘automatically’ be an RA;

What are the potential solutions?

Aircraft Operators

Remind flight crews that, if able, they are expected to comply with ATC instructions regarding rates of climb and descent.

ANSPS

Remind controllers of the possibility of “nuisance” RAs when vertical speeds exceed 1500 ft/min when approaching a cleared level and there are other aircraft in close proximity. (1500ft/min in itself does not mean that there will be an RA - it depends whether there are other aircraft in

[TFEV1909]

Well that’s around 8000 hrs more than I have Maybe I worded it too strongly, but I do honestly mean that it is interesting to see those differences.

[JetWash1023]

Absolutely! I’m only here for the discussion, it’s really interesting.

I’ve genuinely never heard of this SOP, so it’s good to learn what other operators do and I guess why they do it.

One thing will never change, all these airlines fly the same aircraft yet they somehow manage to come up with a thousand different ways to do the same job, it’s mad really.

[DrVenkman3876]

You guys should look back a couple weeks on the PMDG forums and see the discussion about why Southwest in the US sets the final MCP altitude to 0000 rather than the go-around altitude. That was an interesting discussion too.

[mhron]

Looking at that RTE page… Why is it that mess? I’ve never seen anything like that when entering waypoints. After FAMUK on the next line there should be Q3 airway with FOWND as the end point

[JetWash1023]

I’ll bet!!

[mhron]

Ok, I’m not booking any Southwest from now on I must find that discussion.

[PluckyUnderdog]

I haven’t looked at that, but I may well do. Seems awfully counter intuitive. I’d have thought that logically you’d always set MCP altitude at the go around altitude, on approach.

[PacificSet90456]

When I first opened the various settings before my first flight, I noticed in the setup - aircraft - failures it shows “Active 1” and the problem with hydraulics (sys qty refill req) was enabled and all others disabled. If I didn’t do anything, then hydraulics would be the first failure. I disabled it because I didn’t want to start having problems right away. Not sure why this is enabled.

[SuperSixBravo]

I read it, it was an interesting thread. I think in the end it boiled down to old habits die hard. But it is definitely a good read.

MCP altitude after capturing glidescope. Most airlines use go around...

[gordongreig]

This sounds like something bugged with the start up panel state. Try reloading the panel state (e.g. cold and dark etc) to see if that clears it, or perhaps the install got bugged somehow - a reinstall should fix it.