Globe Cargo

Dear Guys,

I just started thinking how does this bank angle function work in real life.(adjusted using heading select button) Is or most pilots leave it at Auto, or do they use 5, 10 degree angles? Does it depend on the amount of passengers? Size of plane? Or the flight plan hoping no large turns?

Does it matter or change if it is Cargo Plane?

Very curious how it is used! Appreciate all feedback!

Happy Flying!

I don't know what the real world does but I leave mine in auto 100% of the time.

I leave mine on Auto.

Dennis

It is left on auto as Justin says. That means basically the faster the aircraft is travelling the less the bank angle will be so as not to strain anything. Also, and most importantly, it will limit the bank angle when it is travelling slowly, for instance after take-off and on approach tp prevent any possibility of low speed stalls. Remember that stalling in this case means stalling the wings, not the engine or engines. The wings are, or worse, one wing is going too slowly to create enough lift to keep the aircraft flying.

When you learn to fly in real life, they take you up nice and high and get you to stall the aircraft, Most of the small ones have a very gentle stall, they give a bit of a "shudder" or shake and the nose drops. They pick up speed automatically when the nose drops and away you go again. But it is interesting to then see how much altitude you have lost in the stall. Higher speed and larger aircraft can be very nasty when they stall, even flying straight.

They, then do this while the aircraft is in a turn (IE. banking). The difference is amazing and can be very frightening.

The great danger to stalling is when you are in a turn and the aircraft is, of course, banked for the turn. At this time the upper or outer wing is travelling faster than the lower or inner wing, and the upper wing creates more lift than the lower one because of the speed difference. Also, the lift and drag coefficients have changed and the wings are not producing the same amount of lift (remember that lift acts vertically upwards). What happens in this case is that the lower wing stalls whilst the upper one is still producing lift. Imagine what happens then.....

The aircraft will try to increase the bank, or turn onto it's back, as well as falling very rapidly, This happens so quickly and, because the aircraft is still close to the ground, you do not have the time to recover. so when you are going slow on departure and arrival you have to be very carefull.

The majority of light plane accidents are caused by these slow speed stalls. For instance when you are turning onto
final and might slightly overshoot the line of the runway, you tend to tighten the bank angle to turn faster and WHAM, you and you passengers are dead.

John

Thanks for the feedback!

Thanks John, for the detailed information!.

I believe some software programs are not accurate as I remember, when taking off and if the turn to flight plan was a wide turn, and when you hit nav button, the aircraft made a fast turn, even though the auto was on for the angle. Again, maybe the software was not accurately realistic on this area.

Happy Flying!

Yes Dennis, - As long as it works right on the real thing......

John

Takeoff bank angle is much less of a concern due to the relatively clean configuration (speed / power / flaps / gear) compared with landing config. If your talking about a PMDG product, their auto settings will be right on, it's not exactly a complex calculation

In HDG SEL or LNAV / AUTO mode, the AFDS & FMC calculates the bank angle limits based on TAS, flap position and aircraft weight. In HDG SEL mode, 15 degrees is set between 332 and 381 kts. If in LNAV, 15 degrees is set when speed is below V2+90 kts and flaps are up, or an engine fails when flaps are not up, or TAS is greater than 381 kts; bank angle is limited to 8 degrees when below 200 feet AGL; else 25 kts is used (that's why you saw a good old deliberate 25 degree turn right after takeoff - your flaps were not up and you weren't going faster than 332 or 381 kts and I assume you didn't have an engine failure). When something other than auto is selected, there will be no bank limitations regardless. This is all fully and accurately modeled in the PMDG 744.

I'm lazy and don't want to remember all that crap so that's why I leave it in auto!

I was actualy referring to the real thing, not the flightsim, and at the much lower speeds on approach.

Accidents, usually fatal, have happened so many times due to this. The departure is not as critical but you still have to be carefull.

John

Are you saying accidents have happened because the heading select bank angle was in an aggressive manual setting (25 degrees) or because auto didn't work right?

Oh for goodness sake, what do you think I'm talking about?

Read the post where it says about tightening the bank angle to line up on the runway and situations like that. Not about sitting there and pushing buttons.

"What we have here, is a failure to communicate!"


I know what your talking about as it relates to bank angles and stall speeds, lift coefficients and all that aerodynamic stuff. In clean configuration a 30 degree bank, increases stall speed by 7.5% and has a stall speed ratio of 1.05 at 25 degrees of course these numbers don't take density altitude or calibrated airspeed into account.

I get it, don't stall.

I was just responding to the OP comment regarding PMDG's modeling accuracy of the auto bank angle function.

Hi,

Sorry I'm a little late, but I am new in the comapny, and I just wnat to add something.
First of all, the bank limit selector only applies when in heading select roll mode!
As previously said, the auto mode gives you a bank that varies between 15-25 degrees, depending on TAS, FLAP position and V2. you need to have at least V2+15kts for a 25 degrees of bank. In case of engine failure, you want to fly to V2 exactly in order to have the best rate of climb possible, so you will be limited to 15 degrees of bank. Also in high speed in cruise, the bank will be limited to 15degree for passenger's confort. All that is done automatically with the auto mode.
If for some reason, you want to change the maximum bank angle, you can change it into another value. That will be done regardless of airspeed!
In real life, we leave it 99% time in auto. We change it sometimes in "exotic" countries where the radar vectors are not always very good to optimize our LOC interception for instance.

Hi Mathieu,

is it specific to the "new" family of 757/767 747-400 ?

i ve made as an observer a POGO CDG to ORY in a classic 747 and the Loc interception was very hard and far from 80° off the loc slope ... i made a remark to the pilots and they said they were trying the autopilot we re at that time i m pretty sure in 40° level ... the classics didnt have the protections now fitted in the new gen aircrafts ...

phil

Hi Phil,

well, you've got a point: 744 is not a 757/767. But If you have a closer look on the MCP's themselves, they are almost the same!
To be honest with you, I checked on the 744 AOM to be sure about what I said !
You can actually intercept a LOC with max 110 degrees off the loc slope (it's again based on the 757/767 SOP's)
We arm the LOC when you are cleared to intercept and when the loc appears on the good side on the ADI/PFD.
I don't know about the 747 classic, but I'm sure that If you try to do the same with a -400, you will hear the very pleasant sound of "bank angle", and you will be invited for a small meeting with your chief pilot and your manager!