Using 1/2 bank in the Flight Levels

[VADriver]

Some pilots choose to use 1/2 bank (CRJ) at teh flight levels for a smoother ride or "stall protection".

Is this a valid concern.

Also, if ATC gives a heading to aviod traffic, is ATC expecting the jet to turn twice as fast....

Any other points as well??

 

[MauleSkinner]

Some pilots choose to use 1/2 bank (CRJ) at teh flight levels for a smoother ride or "stall protection".

Is this a valid concern.

Also, if ATC gives a heading to aviod traffic, is ATC expecting the jet to turn twice as fast....

Any other points as well??

None of the jets I've flown are anywhere near Vs, even at the charted max altitude for weight. I've seen some low-speed mach buffet, though...max altitude for the weight, and an abrupt load due to either turbulence or mishandling.

I don't know about the CRJ, but the Hawkers have a chart for 1.3g/1.5g buffet boundary (I can't remember the exact terminology offhand). In smooth air, a 30-degree-banked turn (autopilots usually run 25 degrees) is only about 1.15 g's, but a little turbulence could push you into the mach buffet, where half bank has you down around 1.05 g's, so there's a little more cushion.

As far as the turns, my experience is that they're turning you for something quite a ways down the road...turn rate or radius really isn't an issue. Remember, even at full bank, you're still probably quite a bit less than half standard rate at high-altitude cruise speeds. I'll let you look up the formula

Fly safe!

David

 

[rickair7777]

Some pilots choose to use 1/2 bank (CRJ) at teh flight levels for a smoother ride or "stall protection".

Is this a valid concern.

Also, if ATC gives a heading to aviod traffic, is ATC expecting the jet to turn twice as fast....

Any other points as well??

Actually the CRJ turns on the half-bank all by itself at 31,600. I believe you could turn it back off, but why would you want to if the mfg thinks it important enough to automate? It is for stall protection.

ATC expects IFR airplanes to turn at standard rate only if their current speed allows them to do so without exceeding 25 degrees bank, or an appropriate bank angle specific to the airplane...that's what half-bank does, limits bank to a value suitable for the airplane, therefore it is legal. ATC does not expect jets to make tight turns, especially in the flight levels.

The CRJ has a turbulence mode which dampens autopilot response to prevent the airplane from jerking itself around in response to turbulence. Half-bank is not normally used for turbulence. If you leave the turbulence mode on for an approach, it will dampen the autopilot's attempt to capture the LOC, and you will blow through final...

 

[Oakum_Boy]

If you leave the turbulence mode on for an approach, it will dampen the autopilot's attempt to capture the LOC, and you will blow through final...

The autopilot will automatically disengage the turb mode when an on-side localizer is captured, but if you're close to the course and turning slowly, there is a chance you will overshoot by some degree.

 

[avbug]

When I'm flying an aircraft with a half bank mode, I usually engage it away from the terminal area, but ensure it's disengaged when starting any terminal proceedures including the arrival proceedure. I also disengage it if any course changes exceed more than about thirty degrees.

I've made the mistake in some systems of leaving a softflight type mode engaged as well as a half bank mode, and had overshoots on a localizer, or course overshoots on an arrival...and I got screeched at by ATC on one occasion when half bank told the turn anticipation function to turn a lot earlier than I had intended.

The aircraft may use it for "stall protection," but I have never used it for that purpose. I think it's a little better for passengers. That's why I use it.

 

[great cornholio]

In the 145 if you are in Heading mode it will go to low bank mode automatically above FL250. If you are in LNAV mode above FL250 it will still use 25 deg of bank if it needs to. Who knows why EMB decided on the 2 different logics between to two modes.