Leo schoonbroodt

PMDG 737NGX Handlandings

25 posts in this topic

Dear Simmers,

I have a question about manual landing the PMDG 737NGX.

As i am practicing manual landings with this beautiful plane i find that if i don't flare, it will  automaticcaly decrease vertical speed and land smoothly almost like it does a LAND 3 which it doesn't because it is under FD not under CMD and sometimes even on a runway without ILS.
If i start to flare at about 10 feet AFL it floats forever and i have to forcibly push the nose down.

I am landing with AT active.

Anyone who has a tip or suggestion what causses this behavior?

Thanks for any sugesstion!

 

Leo Schoonbroodt

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Hi Leo, there isn't much of a flare. First, speed is the most important variable and I will bleed off the +5 to decay to Vref over the numbers, throttles closed by 30 ft, and watch the far end of the runway.  Watching the far end of the runway gives you the best visual clues to sink rate and flare angle.  If you stop the sink you flared too much,,,, carefully reduce the flare angle.  I usually disconnect AT when i disconnect AP about 1000 AGL.

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Leo, i always try to land manually and I don’t experience as u describe an automatic soft landing, not like on auto. It can be pretty hard if I don’t flare. Now I don’t flare much and I too look  down the end of runway to have an idea of my sink rate. But If I don’t flare At all that’s pretty harshs. (not sure as I cannot look at my rate while I’m looking the runway and the recording playback unfortunately has my panels blacked out so I cannot review the numbers). If I flare correctly I think I end up on 0.2ish rate. But sometimes I pull a little too much and float a little and yes I push just a little the yoke to re-descent. But I know that’s my mistake often caused by fear of slamming plus trying to get centerline. Even when I float however  most times I touch down within the safe zone and never beyond the very last two markings of the first half.  So I consider that still a decent landing.  when I review everything visually looks good to me as as the real landings I see at the airport. 

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21 hours ago, downscc said:

Hi Leo, there isn't much of a flare. First, speed is the most important variable and I will bleed off the +5 to decay to Vref over the numbers, throttles closed by 30 ft, and watch the far end of the runway.  Watching the far end of the runway gives you the best visual clues to sink rate and flare angle.  If you stop the sink you flared too much,,,, carefully reduce the flare angle.  I usually disconnect AT when i disconnect AP about 1000 AGL.

Follow that and you will be fine. 

To add to that, in the FMC there’s an option to show were you throttle is in relation to the NG’s set to show . Around 1400 ft turn AT off and watch your speed.

30ft cut the throttle and do as Dan says. The NG is a peach of an aircraft to land. 

Aim to land at - 135 to 185 if you can. 

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Not sure if you are coming to the NGX from the FSX default 737, but I remember early over flaring way too much when I first switched over. I think if you give it time you will get used to the NGX over the old default 737. They say the NGX flight dynamics make the default planes dynamics seem cartoonish.

I remember the default 737 felt like you actually had to lift the nose and pitch up to land, and the NGX felt like you just have to pitch level, although if you watch an NGX land on replay the nose still pitches up (back wheels always touchdown first).

It was a challenge to get it right having flown the default 737 for years, but you'll get used to it.

Also like others have said, learn about V-speeds and sticking to them on approach, learn about wind corrections and the like and learn how to bleed them off just before touchdown. Also assign a trim switch too you'll need to adjust it after you disconnect the AP if you are doing manual landings.

None of those things I ever even knew about on the default plane. They actually matter in the NGX.

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Thanks Guys, a lot of usefull information.

Tomorrow I will start landings without AT and bleed of the +5 wind correction to get to Vref at touchdown.
I always landed with AT because that would give me the best Gust protection accordingly to what I have read, but indeed I was already expecting that AT wil give more power to hold the commanded speed when the nose is raised for the flare.
Should't it not automatically go in Retard mode when below 27 feet or is this only when under AP?
Could that be the "auto" flare I experience?

And Yes, I indeed switched from the default 737 to the NGX, beatifull simulation.

Still many Things to learn!!:ohmy:

Thanks again for all the sugestions.

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The auto throttle is not to be trusted to provide fast response for gust protection, generally the more the challenging conditions, the more caution you should exercise using autoflight systems. Besides, getting back to basics is always a good thing to do. Handflying is something that is done more often than simmers tend to think IRL.

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1 hour ago, Leo schoonbroodt said:

Should't it not automatically go in Retard mode when below 27 feet or is this only when under AP?

Perhaps but that means it is just starting to retard the throttles whereas most of my normal landings have the throttle closed by that time.  Keep in mind that automatic landing is not a normal landing and is usually only done when executing a CATIII approach in very marginal conditions.  Aircraft vary... for example, the 777 is normally landed with AT on for all landings.

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Ok, thanks.

Still a lot to practice:blush:.

Did a landing without AT, but its demanding to look at airspeed, descend rate an runway allignment all at the same time, so crashed it because airspeed dropped to much.

Its hard to land this way even if I allign throttles to the AT position before disconnecting, but then, I will keep practicing. 
I am not a simmer for that long and luckily no real passengers aboard!!
Normally I handfly untill at cruize level and then again from final approach fix of ATC to Landing but always with AT active.

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3 hours ago, Leo schoonbroodt said:

Ok, thanks.

Still a lot to practice:blush:.

Did a landing without AT, but its demanding to look at airspeed, descend rate an runway allignment all at the same time, so crashed it because airspeed dropped to much.

Its hard to land this way even if I allign throttles to the AT position before disconnecting, but then, I will keep practicing. 
I am not a simmer for that long and luckily no real passengers aboard!!
Normally I handfly untill at cruize level and then again from final approach fix of ATC to Landing but always with AT active.

Use the HUD... that puts the airspeed right in front of your eyes while you are watching the landing.  Also, don't overcontrol. Very small pitch and power changes are important to success.

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4 hours ago, Leo schoonbroodt said:

Did a landing without AT, but its demanding to look at airspeed, descend rate an runway allignment all at the same time

Welcome to instrument flying!

Developing a good scan will help. I would slightly disagree with Dan's suggestion of using the HUD: a solid instrument scan is a very desirable basic instrument flying skill to develop, and whilst HUDs are all well and good they are not entirely without their problems; there can be a tendency to focus on the HUD information to the exclusion of the outside world or, indeed, other information inside the cockpit (so-called 'attention tunnelling') and in some cases the HUD can actually reduce situational awareness.

Remember:

Power + Attitude = Performance

In other words, a given N1 setting, plus a given pitch attitude, in a given configuration, will consistently deliver the same performance (e.g. straight and level flight/a three degree glidepath descent/a climb at a particular airspeed etc). In general, large jets are flown 'by the numbers' -- I don't know the datums for the 737, but you can find them by configuring the aircraft for landing (gear down, landing flap set, speed at Vref +5) and establish on the ILS with the autopilot and autothrottle engaged and noting down the pitch attitude from the ADI and the power setting from the N1 gauges (if you were particularly interested you could try at different weights, and also F30 and F40: in general higher weights will require slightly more power, and F40 will result in a slightly lower nose attitude than F30 - however, if you get the numbers for an intermediate weight at F30 and also at F40 you will have a good basic datum to start with).

As Dan says, small smooth corrections are the order of the day; only a degree or two of pitch attitude change at a time, returning back towards your datum pitch once you have regained the glide path, small thrust changes (but again you don't want to be going too far from your datum setting) and no more than about 5 degrees of bank once established on final approach. If you are going outside of those parameters then your approach is probably not stable and you might well be advised to throw it away and try again. Remember, it is always better to make a small correction early than a large correction late.

In terms of your instrument scan -- there are various options out there, but to start with I would suggest trying what is known as a "selective radial scan". The object of the instrument scan is to always be looking at meaningful information; simply attempting to look at all of the instruments all the time does not achieve this and actually just means you're wasting time looking at non-essential information. So the idea is that you select the instruments most appropriate for the manoeuvre you are carrying out and scan those instrument most frequently, with occasional glances at the other instruments.

Because power + attitude = performance, arguably the most important instrument is the ADI: this is the only instrument that directly gives you pitch and bank information (and once we have set the desired power, it is unlikely to change much). So the scan always starts with and returns to the ADI.

The 'radial' scan is referred to as such because you start at the ADI and scan radially outwards to another instrument, then return to the ADI, then scan out to another instrument and so on. It is "selective" because, as mentioned, you are primarily going to scan the instruments most important to the phase of flight/manoeuvre, so for an ILS approach these might be the localiser, glideslope and airspeed indicator, with occasional glances at the other instruments (particularly the VSI and HSI).

Make sure you look at each instrument for long enough to obtain the necessary information from it, whilst avoiding fixating on a particular instrument (for instance, you wouldn't want to be staring at the glideslope, wondering how you got two dots low, whilst forgetting to look at the localiser and ending up drifting well off course).

Obviously as you get closer to the runway you will want to start incorporating the outside world in your scan to a greater and greater extent, yet still using the selective radial scan technique to include airspeed (in particular) and other information.

Developing an effective scan takes some effort and it is a perishable skill -- you need to practice regularly. However, with practice your scan rate will get quicker and you will be able to pick up deviations and anything "unusual" very early.

Good luck!

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2 hours ago, downscc said:

Use the HUD... that puts the airspeed right in front of your eyes while you are watching the landing.  Also, don't overcontrol. Very small pitch and power changes are important to success.

+1 on this. 

I manually land all flights, and the HUD is clutch. 

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On 10/7/2017 at 3:05 PM, Leo schoonbroodt said:

Dear Simmers,

I have a question about manual landing the PMDG 737NGX.

As i am practicing manual landings with this beautiful plane i find that if i don't flare, it will  automaticcaly decrease vertical speed and land smoothly almost like it does a LAND 3 which it doesn't because it is under FD not under CMD and sometimes even on a runway without ILS.
If i start to flare at about 10 feet AFL it floats forever and i have to forcibly push the nose down.

I am landing with AT active.

Anyone who has a tip or suggestion what causses this behavior?

Thanks for any sugesstion!

 

Leo Schoonbroodt

A real world '37 pilot here. The AT should be disengaged with the AP. You'll get into phugoid oscillations due to the constant changes in autothrottle as you pitch up and down, you'll be constantly fighting it. Those high bypass engines cause large pitch changes. It's a bit harder to break down power and pitch to control speed and glide path than say a light aircraft meaning you're always going to have to work both at the same time.

The autothrottle works best when the autopilot is engaged. The only time the autothrottle is engaged for landing is when conducting a CATII or CATIII autoland. I've set up PMDG to override autothrottle in ARM mode and to show my throttle position. I match my throttle position to the thrust position before disengaging AT.

The real airplane, I have my hand on the throttles throughout the approach and follow through with what thrust I need without disengaging the clutch, so I am always aware of my thrust. I have had the AT fail even without disconnecting even though the correct FMA's were displayed. The AT disconnecting is less conspicuous than the AP disconnecting as all you'll see is the AT P/RST flashing yellow or red. This tactile feel of the autothrottle operating is missing in the simulator so it's even more important. If it's visual I disconnect both when I feel like hand flying, and when it's IFR they're off at minimums. My company has a policy that both are off no lower than 20' below minimums.

The airplane is the easiest airplane I have landed in my career. Hold power and pitch. She'll settle in ground effect at 20'. Close thrust and hold it in ground effect. She practically is in the flair attitude the entire approach so not much pitch is needed. There is a service bulletin stating not to land her soft. "Boeing" is the sound she is supposed to make upon impact.

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15 hours ago, downscc said:

Use the HUD... that puts the airspeed right in front of your eyes while you are watching the landing.  Also, don't overcontrol. Very small pitch and power changes are important to success.

+3 - although I feel like I am too dependent on it at times

In real world I can imagine a pilot has a sense of acceleration / deceleration via being able to *feel* the plane accelerating / decelerating. Of course, we do not get this sensation in the sim, so we have to use visual cues. And the HUD has the little over/under speed bar just to the left of your sight line which I am woefully dependent on because I cannot feel the plane accelerate / decelerate at the point of the landing where you need to have your eyes on the runway.

A few other things to consider - adjusting the throttle does affect your pitch in the NGX. When you close the throttles just prior to touchdown, the nose of the plane will dip. If you jam the throttles up, the nose will pitch up. This is because the thrust / drag produced by throttling up / down will rotate (pitch) the plane similar to why the front end of a car rises if you jam the gas, or falls when you jam the brake. I don't remember the default plane doing this.

Also, there's a bit more to that +5 in the VREF +5 - however even since I've been checking and calculating it every single time, it seems very rarely that the +5 ever exceeds +5, but it can happen.

https://www.avsim.com/forums/topic/379298-headwind-component-vref-calculation-clarification/

 

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15 hours ago, MeatServo said:

The AT should be disengaged with the AP

 

15 hours ago, MeatServo said:

The only time the autothrottle is engaged for landing is when conducting a CATII or CATIII autoland

Not necessarily. My company allows, and encourages the use of A/T to touchdown on all landings.  Unless a QRH procedure requires the A/T to be off I leave it on all the time.

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