Try telling that to a passenger in a 45 degree bank! you will feel it.

 

Yes, Jack, I thoroughly understand the dynamics associated with turns.  Last I checked, however, the HDG limiter doesn't have a 45 degree mark, and the AP never uses 45 degree turns in any other mode. It's not standard to make 45 degree turns at all in transport category aircraft.

 

You'll note I used the accepted normal max of 30 degrees when I referenced the g forces people (or animals) would feel.

Yes, Jack, I thoroughly understand the dynamics associated with turns.  Last I checked, however, the HDG limiter doesn't have a 45 degree mark, and the AP never uses 45 degree turns in any other mode. It's not standard to make 45 degree turns at all in transport category aircraft.

 

You'll note I used the accepted normal max of 30 degrees when I referenced the g forces people (or animals) would feel.

 

If it's done right, you'd only feel G through the 'floor'. at 60 degree bank it'd be around 2G. No side-to-side force if it's a correctly co-ordinated turn, just 'feeling heavier'.

O.K. guys. Until now it was all about g-forces or pax-comfort.

But what about limiting the bank angle during high altitude climbs due to performance issues?!

As "my" rule of thumb the bank angle selector keeps being set to 30 DEG as long as procedures have to be flown as coordinated standard turns. At 230 kts this normaly requires 30 DEGs of bank (240kts/31DEG, 250kts/32DEG, ..., 530kts/60DEG).

But after overflying the last SID waypoint it is a good idea to set the bank limiter to 15 DEG. This will help keeping the climb rates as high as possible.

Performance is generally no problem for a more or less "empty"  6/700, but a fully packed 8/900 starts descending when forced to a 30DEG bank turn at FL360...

And , as we all know, atc controllers like at least 1000 fpm.

(BTW: setting the bank limiter back to 30DEG when entering the STAR is a must, of course...)

 

Greetings,

Claus

I'd offer a slightly different perspective. The radius of the curve is directly proportional to airspeed and height above ground....all very important when considering the aircraft's ground track and overflight restrictions. Therefore I select 25 on the ground, switch to 30 at FL100 in the climb and back to 25 at FL100 in the descent.

O.K. You are right in differenciating between IAS and TAS.

This would, concerning the rule of 250kts (IAS!) below 10000ft, result in a speed difference of at least 50 kts (250kts IAS = 300kts TAS @ 10000ft). So bank angle could be increased at high altitues and respectively high TAS in order to "stick with the pattern". So far, so good. But "high-speed"-stick-to-patterns (e.g. 450kts = 52DEG bank!) don't really exist. So "in practice" 30DEG for patterns, 15DEG for climb/cruise works fine for me. (The idea: shallow bank angles in order to keep good climb rates at higher altitudes, less pitch trimming, less thrust corrections)

OFF TOPIC:

But things are even more complex: Patterns and SIDs/STARs are "3D-objects", that are reported in knots IAS but must be flown actually in kts GS (knots ground speed). It is "impossible" to fly a perfect pattern as a human pilot, as wind influences inconsistently every second of flight. Only IRS/GPS-systems are able to fly a congruent pattern. This way hand flown "unshapely" hold-patterns were accepted by atc. Nowadays RNAV-equipment is mandatory and makes pilot's brain free for other tasks...

ON TOPIC:

I fly the "sharp corner"-legs of SIDs/STARs with Flaps 1 @ 230kts IAS. This would result in maximum banking error of 4.6 DEG (max below FL100: 230IAS=30DEG, 276TAS=34.6DEG). Tight procedure turns requiring exact pattern congruity therefore are published explicitly with lower speeds (kts IAS).

 

Greetings,

Claus

Wow, you guys are really putting a lot of effort in to this.

 

RW, we're not touching that knob that often. I did last week when deviating around thunderstorms at cruise. Other than that, it's pretty much parked at 25.

 

Claus, unless you're doing STARs and SIDs in HDG SEL, the bank angle limiter makes no difference.

 

 

As "my" rule of thumb the bank angle selector keeps being set to 30 DEG as long as procedures have to be flown as coordinated standard turns. At 230 kts this normaly requires 30 DEGs of bank (240kts/31DEG, 250kts/32DEG, ..., 530kts/60DEG).
But after overflying the last SID waypoint it is a good idea to set the bank limiter to 15 DEG. This will help keeping the climb rates as high as possible.
Performance is generally no problem for a more or less "empty"  6/700, but a fully packed 8/900 starts descending when forced to a 30DEG bank turn at FL360...

 

Not bad thinking Claus, but as Matt noted, this is only valid for HDG SEL mode... if you fly the route in LNAV, the bank selector does not apply.

Claus, unless you're doing STARs and SIDs in HDG SEL, the bank angle limiter makes no difference.

Not bad thinking Claus, but as Matt noted, this is only valid for HDG SEL mode... if you fly the route in LNAV, the bank selector does not apply.

 

Gentlemen, that is absolutely true. Banking limiter setting has only effect on HDG SEL.

LNAV mode limits itself to 30DEG banks and so overshoots on a regular basis if speed is too high for the flown turn. This is sometimes the case on SIDs flown with the 250kts IAS climb speed limit (LNAV 30DEG bank is only sufficient for 230kts (GS!)).

STARs flown with the standard 240 kts IAS FMC descent speed limit are also problematic for the same reason. If there is significant tail wind, the problem gets worse.

It never the less works, because most turns in procedures are wider than the 2 minute standard turns (except holdings of course (!) which have their lowered optimum speeds).

 

I very much handfly the SIDs below FL100 (with A/T in VNAV), use CWS P until reaching FMC econ climb speed and follow the route using CWS R. (FD is set to LNAV+VNAV). If LNAV produces a steep turn resulting in a climb rate of less than 1000 fpm (happens regulary on heavy GW, high ISA deviation, turning into tail wind situation or shifting winds), I ignore the FD and fly the bank "on own discretion" to keep V/S greater than 1000 fpm.

But this "own discretion" reaction is somewhat difficult if the A/P is already in CMD mode on VNAV+LNAV. One could try to switch the CMD vom VNAV to V/S +1000 ft mode, which results in unsufficient thrust (an could result in buffeting on high altitudes). So that is no good choice. Leaving the LNAV mode set to ON results in a 30 DEG bank with 0 fpm climb (or even a start of descent). This is annoying for the atc controller but can be dangerous in mach altitudes as this behaviour of LNAV leads to buffeting very fast.

-BREAK-

It is always a good idea to set the heading bug on the direction (MH) LNAV actually flies you to. And if the above mentioned situation comes where LVNAV makes you hold your altitude because of steep turns, just turn on your selected heading using HDG SEL with bank limit set to 15DEG.

This will keep approx. 50% more of the lift produced by your wings for your climb than wasting it for fast direction changes...

 

Greetings,

Claus

 

 

It is "impossible" to fly a perfect pattern as a human pilot, as wind influences inconsistently every second of flight. Only IRS/GPS-systems are able to fly a congruent pattern. This way hand flown "unshapely" hold-patterns were accepted by atc. Nowadays RNAV-equipment is mandatory and makes pilot's brain free for other tasks...

 

Even then, though, it's not going to be a perfect racetrack, and this doesn't have to do with human precision at all.  It has more to do with having to adjust the angles to make all of the legs fit into so many minutes (if using timing).  The inbound leg is generally 1 minute (unless otherwise specified), which means that the time is fixed.  As time is fixed, it becomes distance that varies (as you're likely utilizing a set speed to make life easier).  In order to increase or decrease the distance on that leg, the time on the outbound leg is adjusted.  In order to correct for the wind's effects during the turns, one turn will be very narrow, and one will be very large (in radius), which requires you to actually fly an angled outbound course as drawn on the ground.  As such, you're correctly not flying a perfect racetrack shape.

 

To give everyone a little insight, controllers are taught to know this, and the scope depicts quite a large, awkward shape to be protected:

 

The egg-shaped areas are the holding fixes right at the entry into Raleigh TRACON (RDU).  Note that, as all of these are standard (right) turns, the left edge is always straight, with the variable right edge to accommodate wind drift.  As these are en route holds and not parts of procedures, they aren't "protected" in the sense that instrument approach holds are protected (where, at lower altitudes, terrain is more of an issue); rather, they're protected more in an ATC procedural way.  ATC keeps that side protected (as depicted laterally), and you're also often kept at a segregated altitude from the normal STAR profile, just in case.

 

So...a little insight into hold mechanics and why controllers never look puzzled or ask you why your pattern looks a little awkward.

Gentlemen, that is absolutely true. Banking limiter setting has only effect on HDG SEL.

LNAV mode limits itself to 30DEG banks and so overshoots on a regular basis if speed is too high for the flown turn. This is sometimes the case on SIDs flown with the 250kts IAS climb speed limit (LNAV 30DEG bank is only sufficient for 230kts (GS!)).

STARs flown with the standard 240 kts IAS FMC descent speed limit are also problematic for the same reason. If there is significant tail wind, the problem gets worse.

It never the less works, because most turns in procedures are wider than the 2 minute standard turns (except holdings of course (!) which have their lowered optimum speeds).

 

I very much handfly the SIDs below FL100 (with A/T in VNAV), use CWS P until reaching FMC econ climb speed and follow the route using CWS R. (FD is set to LNAV+VNAV). If LNAV produces a steep turn resulting in a climb rate of less than 1000 fpm (happens regulary on heavy GW, high ISA deviation, turning into tail wind situation or shifting winds), I ignore the FD and fly the bank "on own discretion" to keep V/S greater than 1000 fpm.

But this "own discretion" reaction is somewhat difficult if the A/P is already in CMD mode on VNAV+LNAV. One could try to switch the CMD vom VNAV to V/S +1000 ft mode, which results in unsufficient thrust (an could result in buffeting on high altitudes). So that is no good choice. Leaving the LNAV mode set to ON results in a 30 DEG bank with 0 fpm climb (or even a start of descent). This is annoying for the atc controller but can be dangerous in mach altitudes as this behaviour of LNAV leads to buffeting very fast.

-BREAK-

It is always a good idea to set the heading bug on the direction (MH) LNAV actually flies you to. And if the above mentioned situation comes where LVNAV makes you hold your altitude because of steep turns, just turn on your selected heading using HDG SEL with bank limit set to 15DEG.

This will keep approx. 50% more of the lift produced by your wings for your climb than wasting it for fast direction changes...

 

Greetings,

Claus

Claus,

There's a lot of thought and theory in your post. However, I don't think some of your techniques would pass muster on "the line."

@ scandinavian 13:

Very interesting "scope shot", although it was difficult to be recognized on my Samsung S3 outdoors today. At home I just took a look at your post on my Laptop.

I have an awful lot of respect for atc controllers. I used to fly C172 for about 12 years (VFR only) and the best part of it was always departing and arriving from and to the EDDH CTR.

It was big fun and sometimes adventurous! :-)

 

I used to enjoy TRACON 2 for Windows 3.1 by Wesson back in the mid 90s during the time I made my PPL. Found this on the net:

http://retrogamesappreciation.wordpress.com/2012/04/24/atc-series-part-3-tracon-2-for-windows-flight-control/

That's a long time ago, boy.

I followed your Link http://vataware.com/...cfm?id=12060003 inside this thread.

I it is quite amazing to see what is possible and being done today. I am now thinking about joining vatsim, but I am afraid the rest of my free time won't allow me to do scheduled flights... So I might stick to the spontaneous "rc4's" or just "self-type-ratings"...

 

I am reading the PMDG B737 NGX forum since september 2011 and would like to thank you personally for all the input you provide. I appreciate it very much!!!

 

Greetings,

Claus

Claus,

There's a lot of thought and theory in your post. However, I don't think some of your techniques would pass muster on "the line."

Hi Matt!

I know, I even hope that "nobody" takes it too serious.

It is just what I experienced inside the simulation and is a work around for that sometimes problematic automations.

I used to be an Airbus fan (<enthusiast, not the blades!), but over the time I got a different view on automation. The Boeing concept, in my view, is "at the end of the day" more pilot friendly. It incorporates pilots presence in the humanistic way: pilot to machine and not the other way around. Funny though, that even VNAV/LNAV can sometimes be a step to far towards automation and can cause crew overload.

In Germany we say: "the best automation is the one you can turn off!" This is very true for cockpit concepts...

 

Greetings,

Claus

Claus,

There's a lot of thought and theory in your post. However, I don't think some of your techniques would pass muster on "the line."

Hi Matt!

I know, I even hope that "nobody" takes it too serious.

It is just what I experienced inside the simulation and is a work around for that sometimes problematic automations.

I used to be an Airbus fan (<enthusiast, not the blades!), but over the time I got a different view on automation. The Boeing concept, in my view, is "at the end of the day" more pilot friendly. It incorporates pilots presence in the humanistic way: pilot to machine and not the other way around. Funny though, that even VNAV/LNAV can sometimes be a step to far towards automation and can cause crew overload.

In Germany we say: "the best automation is the one you can turn off!" This is very true for cockpit concepts...

 

Greetings,

Claus

 

 

Very interesting "scope shot", although it was difficult to be recognized on my Samsung S3 outdoors today. At home I just took a look at your post on my Laptop.
I have an awful lot of respect for atc controllers. I used to fly C172 for about 12 years (VFR only) and the best part of it was always departing and arriving from and to the EDDH CTR.
It was big fun and sometimes adventurous! :-)

 

Yeah - it can definitely be a tough job.  On the virtual side, it's been pretty fun.  My real world jaunt was a little more frustrating, but it is what it is...

 

 

 

I followed your Link http://vataware.com/...cfm?id=12060003%C2'>
I it is quite amazing to see what is possible and being done today. I am now thinking about joining vatsim, but I am afraid the rest of my free time won't allow me to do scheduled flights... So I might stick to the spontaneous "rc4's" or just "self-type-ratings"...

 

Ah, that flight was a doozie.  I had one route in mind, ended up getting cleared onto another, then got the full picture of the weather while en route and diverted well south of my original route.

 

For what it's worth, you don't have to do scheduled flights (that link you took a look at was flown on an airline that isn't even in business any more).  It's all when you want, for the airline you want (or you can even make up your own - I'm pretty sure I heard an "Air Kevin" on the frequency today).

 

If you have any questions about VATSIM, just shoot me a PM and I'll point you in the right direction.

 

 

 

I am reading the PMDG B737 NGX forum since september 2011 and would like to thank you personally for all the input you provide. I appreciate it very much!!!

 

I really appreciate that Claus.  Thanks!