Inappropriate comments about RJ crash?

[Lear70]

PTCH is different in that it maintains the pitch angle the pilot sets. This is better than Vertical Speed or Speed mode because PTCH mode maintains a contant angle of attack. The pilot doesn't know what AoA he/she is flying, nonetheless it is constant.

True... as long as the airspeed is constant. If your airspeed slows at a given pitch angle, the AOA will inrease, and vice-versa. As long as the pitch angle is reasonable for that altitude (2-3 deg NU), you'll run out of airspeed and vertical climb rate and start descending before you'd ever stall the aircraft.

I used pitch in the Lears but I don't like the way the CRJ handles pitch mode, and I certainly don't like the way it handles speed mode (uncomfortable for the pax as it chases its tail all day), so I use vertical speed and just monitor the airspeed.

The one thing I DO use pitch mode for is extending the flaps on a Flaps 20 aircraft, IF I'm descending. The pitch moment is so extreme going from flaps 0 to flaps 20 that you'll set off the trim clacker most of the time, but pitch mode will simply reduce your rate of descent and you can switch back to v/s or speed mode and dial back in what you need. Much easier on the pax...

 

[FlyChicaga]

Having flown the CRJ since 2000, I climb in PTCH mode. Most pilots question this.

PTCH mode is shunned because it is the default vertical mode. The default lateral mode is ROLL. Roll is isn't good because it can maintain a bank angle of up to 5 degrees. The logic is if ROLL is bad then PTCH is bad.

PTCH is different in that it maintains the pitch angle the pilot sets. This is better than Vertical Speed or Speed mode because PTCH mode maintains a contant angle of attack. The pilot doesn't know what AoA he/she is flying, nonetheless it is constant.

Constant Angle of Attack provides a stable, steady climb up to your flight planned atltitude. There are no oscilations and thus wasted energy. Set the CRJ 200 at 2.5 degrees NU and the aircraft will stop climbing before anything else happens. It can't stall at 2.5 NU. In Speed mode or VS mode you run the risk of exceeding the critical angle of attack if no changes are made.

Thoughts?

I do this in the ERJ, for reasons similar to yours. Also because I can "bug" the desired climb speed, which with a quick glance gives me a good indication of if I'm off from the climb profile. I'm curious on opinions of this for both airplanes.

I keep the airplane out of IAS/MACH mode unless hand-flying (which I do up to cruise often lately), since if you fly into a headwind, such as the jetstream, the airplane will pitch up quickly and give you a huge climb rate. Then, it will drop off and nose over just as quickly. Not comfortable for the paying customers in back at all, nor does it seem like a safe maneuver at FL300+ pitching to 15 degrees!

 

[172driver]

I almost always climb in pitch mode. It is smoother, as you said, especially in really bumpy weather. All the publications recommend holding a constant pitch when penetrating a storm. I figure the same is true in any moderate or better bumps.

We all know speed mode sucks and the pitch oscillations in VS mode, though they are slight in smoother air, can't be the most efficient way to operate.

I'm at Comair and have never had a captain so much as look at me funny when using pitch mode. It's pretty common here. Now roll mode is another story...I do use it occasionally but I have gotten some reactions.

Also, pitch mode makes for the type of climb I believe the airplane is best suited for. Set 2.5 degrees out of 10,000 and it will accelerate up to 320 kts, hold a 1500 fpm climb once it gets there, bleeding the climb rate down to 500 fpm in the mid 20's. After that, you may need one more click of NU to maintain 500 fpm, trading some of your speed. The airplane will quit climbing well before it gets to an unsafe speed, unless you continue to crank in more pitch for some reason, which I don't.

 

[FlyChicaga]

Could you all explain roll mode in the CRJ? What is the max bank angle for it?

I've used it in the ERJ when evading broken buildups on the climbout for a smoother ride. Can give a rapid roll rate if used carelessly, like a damm snap roll. But if used slowly, it is much better than rolling the heading bug back and forth. Much smoother ride.

 

[172driver]

Roll mode is the default mode in the CRJ and is only used to transition between raw data and other lateral modes. There is no way to adjust it...it simply locks the FD at whatever bank angle you were at when you selected it. There is no control to steepen or shallow the bank.

For example, if you are flying raw data and select a vertical mode such as VS, the FD will sync to whatever bank angle you are currently flying. I sometimes use it when things are getting busy and bumpy, I'm established in a turn, and I feel like hand flying might not be the best option. I will simply select AP engage and the AP will default to pitch and roll mode, keeping the airplane in exactly the pitch and bank that I left it in. Before I get to my desired heading/course, I will select HDG or NAV mode.

If you select hdg or nav before you engage the AP, the airplane can get a little confused and shallow the bank, or even bank the other way, while it thinks about things.

The other time you will see roll mode engaged is when we come to the end of our flight plan in the FMS. When we cross the last fix, the AP defaults to roll and we will remain in whatever bank we were in at the time. Not a good time to fall asleep...

 

[surplus1]

PTCH is different in that it maintains the pitch angle the pilot sets. This is better than Vertical Speed or Speed mode because PTCH mode maintains a contant angle of attack. The pilot doesn't know what AoA he/she is flying, nonetheless it is constant.

Thoughts?

I have nothing against the use of pitch mode but please take a second look at what you said. I don't think pitch mode will maintain a "constant AOA" unless you also maintain a constant air speed. What you said may be true if you have enough power to maintain a constant AS at the same time and you use it.

Unless I'm mistaken, which is quite possible, when you set a given pitch attitude and airspeed the airplane "climbs" because you have more power than required for level flight. As the difference between pr and pa narrows, vertical speed will decrease. When you reach an altitude that requires all of the power either being used or available, the climb will stop. If the power is less than required to maintain that altitude, airspeed will decay and AOA will increase even though the pitch attitude hasn't changed.

Unless power available = power requiired (rather exactly) a steady state cannot be maintained and something will have to give.

 

[:-)]

I've got it. Why don't you CRJ people just hand fly to altitude? It sounds as if the airplane requires constant sheparding anyway, so just hand fly and relieve yourselves of the burden.

I think I'd rather just hand fly (act) instead of being forced to REACT to the actions of the autopilot/flight guidance system.

No kidding,
Hobbes

 

[TIS]

Why don't you CRJ people just hand fly to altitude? It sounds as if the airplane requires constant sheparding anyway, so just hand fly and relieve yourselves of the burden.

Well, with DRVSM that could get problematic. You're supposed to use the autopilot when in cruise in DRVSM airspace. It's not too much of a stretch to think that some FAA idiot would come along saying you have to use it for ALL operations in DRVSM airspace.

But that's speculative at best.

I do agree that if your jet doesn't do well in any automatic/pre-programmed mode such as those discussed, you should avoid using them in favor of simply setting a pitch and monitoring the climb for a reasonable rate of climb considering SAT/TAT and flight conditions. Most often it's the vertical modes that someone paid big dollars to get past the FAA certification group that cause the trouble. Lateral modes are generally pretty reliable and fly the plane well.

Just because a mode is there it doesn't mean it's necessarily the right thing to use and it certainly doesn't mean that it's always a good idea to use it. it's important to know your flight director controls and what they do. I saw a reference to a "click of NU" here. Understanding what that will do in a climb, a descent, and in altitude hold mode is important.

It's also important to understand how the AP interfaces with your LRN system. if you get your RNAV from an FMS, it's the FMS that actually commands the bank in order to give it control over intercept plots that it calculates.

Using an AP by rote because it's the way everyone else does it is fine as long as you're not left mystified as to what's happening. There's a book - probably online someplace. It's a good idea to read it at least once.

TIS

 

[Lear70]

The main issue with using roll mode is that you really haven't told the aircraft to do anything except hold a given bank angle.

Heading mode, used in conjunction with the TURB switch, when deviating around cells will give you a nice smooth roll rate and direct control over where you're going. Quite frankly, whenever I engage the autopilot, the TURB switch is right behind it - too many years of flying charter and corporate, I like a smooth ride.

 

[Rez O. Lewshun]

I have nothing against the use of pitch mode but please take a second look at what you said. I don't think pitch mode will maintain a "constant AOA" unless you also maintain a constant air speed. What you said may be true if you have enough power to maintain a constant AS at the same time and you use it.

Unless I'm mistaken, which is quite possible, when you set a given pitch attitude and airspeed the airplane "climbs" because you have more power than required for level flight. As the difference between pr and pa narrows, vertical speed will decrease. When you reach an altitude that requires all of the power either being used or available, the climb will stop. If the power is less than required to maintain that altitude, airspeed will decay and AOA will increase even though the pitch attitude hasn't changed.

Unless power available = power requiired (rather exactly) a steady state cannot be maintained and something will have to give.

Usually, the IAS stays the same, around 290/.70. It does start to bleed off once the jet gets to FL300+. (based on weight/ISA) It decreases, but I don't think the AOA changes too much, especially if one is operating the jet IAW with the flight release and performance charts, but then again, there is no AOA indicator to reference.

Speaking of performance charts. The CRJ chart reference climb capability that is given to pilots (usually in the QRH) to check if they can climb to any given altitude with a given weight/ISA is just one of many. It is for a specific %MAC and pack/bleed setting. IOW, it is a very generalized reference.

Lear70 indicated the same with a constant airspeed. AOA is elementry and paramount in aircraft control, yet "they" seem to keep us pilots from applying it.

I am wide open for a complete understanding... more info requested..... including links...