CRJ Takeoffs and Landings

[h25b]

Sorry to offend you "stiffler", that certainly wasn't my attention. My apologies...

I guess since I mentioned noticing it in the back, that was offensive... So I guess I should mention I used to see it up front also, when I know what the situation was.

As for trying to impress the hot passenger next to me, she was my wife.... (we stopped trying to impress each other years ago
)

And also, If I had a dime for every time I wasn't popular with ATC.... Well, you know the story... Try and remember the whole point of the forum "Stiff", it's informative discussion... Most people, including myself, don't jump in unless we have first hand operational experience on the topic. I think most people are missing "GCD" 's point. That is, when operational conditions allow, I little extra technique, thought, and awareness can make the passengers experience and the aircraft maintenance a little more enjoyable. The latter by the way contributes to the bottom line which, combined with the earlier pays YOUR salary.

There might be a day in the future, like me, that you end up having to be in the corporate world when frightening the wrong passenger can cost you your job or at the very least a regular passenger's confidence.

That's all, again my apologies...

 

[freightdogfred]

Takeoff thrust setting - There are some very good reasons why your FSM or FCOM says to advance the thrust to 70% N1, stabilize, then set takeoff thrust. The stabilization at 70% N1 is to allow for symmetric spool up. Both engines may spool up to 70% N1 at a different rate, but once stabilized at 70%, it is more likely they will spool to takeoff thrust more evenly. Also, by allowing the engines to stabilize at 70% N1, you are checking two other things, proper airflow through the compressor and that N1 is speed controlled to avoid an overspeed when setting takeoff thrust. Setting takeoff thrust from idle is really poor technique and even causes impulse stress to the turbine blades, causing a creep in the blades and eventually failure of the turbine blades, if done very many times.
.

While setting 70% is good technique to ensure symmetrical and stable engine operation, it will do nothing to eliminate turbine bucket "creep" or "stretch". This is a function of repetitive heating /cooling of the metal, and until you see ceramic turbines, you won't stop it. If you wanted to reduce "creep" and extend turbine life, you would be advised to employ a similar technique at the top of descent, reducing power in increments, vs. going from cruise power to idle. I don't fly the CRJ, but most FMC'S calculate profiles on fuel savings so if your a/c has autothrottles, ther's not a lot you can do.

 

[GCD]

Freightdogfred,

You make a very good point about TOD thrust reduction. However, I was talking about impluse stress creep by going from idle to takeof power. It's from GE, not me. It's something to do with going from 400'C to over 800'C in a couple of seconds. The turbine blades are exposed to rapid heating and rapid centrifugal force simultaneously. While it may not hurt the engine if done a few times, over a period of events, the engine life is reduced.

Also, I know the Comair FSM addresses this, but I know a particular FCOM that does not. That is, after start, the CF34 engine must be at idle thrust for two minutes prior to takeof thrust being applied. That also from GE.

As for those of you who think there is no such thing as premature braking - I didn't make those figures up. The figures came from airplane and brake manufacturer test results. However, you fly your airplane the way you want to. I am only offering my two cents worth of advice. Take it or leave it. I am always open to advice, myself.

Also, I am not saying to not use the brakes, as someone eluded. I advocate, as the brake manufacturers do, to make a firm steady application at 80 knots. A brake, by definition, is a machine or device that converts kinetic energy into heat, then dissapates the heat into the atmosphere. Therefore a single firm application produces less heat than a prolonged application, especially a prolonged, light application, as in taxiing.

Beechnut, your company has it right!

 

[ClearRight]

I'll chime in on the incentive to wait until the nose is on the ground before revving up the reverse thrust. I've got about 700 hours in the RJ and until last week I'd frequently do the "shuttle landing"- mains first, fly the nose while bringing the reverse levers up. Last week I landed fairly light so the nose was rather high, I held it up and added reverse thrust. It wasn't immediate, but I ran out of elevator with the nose wheel still in the air. WHAM. I'll not do that again. From now on, it's nose down, THEN bring in the reverse- just like I was taught!

 

[HighSpeed]

What about heating the brakes??

Good thread on the use of reverse thrust, but I was told that heating the brakes by using them more during landing will extend the life of the brakes. ie.) the carriers in Europe that do not use reverse thrust at all, yet enjoy longer brake life than thier U.S. counterparts because they have to stop using brakes only.... If revrse thrust is used primarily, the brakes will not have "warmed up" and therefore will have excessive wear while "taxiing in" to the gate.....

 

[logolight]

As an RJ fo, I've seen captains do everything from deploying the TR's with the nose in the air to not using the TR's at all. I also know from training that with just a little extra control input, the RJ will handel a single engine reverser with little adverse controlability. As far as the stories of the nose slamming onto the runway, I flew with a captain once who would actually increased the pitch of the aircraft by about 3 degrees after the mains touched down and he never crunched the nose onto the runway. One last comment, I have never seen anybody nor myself "derotate" the nose to the point of using full aft elevator. But under certain weights, I have seen the RJ's nose touch down at amazingly low air speeds.




Snooch to the Nooch!

 

[CatYaaak]

[But under certain weights, I have seen the RJ's nose touch down at amazingly low air speeds.[/B]

Having an amazingly low airspeed means your rudder effectiveness is deteriorating rapidly, and since the nosewheel isn't on the ground yet, no nosewheel steering. Weathervaning tendency applies to rollout just as it does on takeoff.

Nose high means poor forward visibility, and increasing the pitch 3 degrees (like the captain you mentioned) means it's even poorer. If you DO have to suddenly apply heaving braking (runway incursion, deer, whatever) and have to get it stopped right NOW, the nose will crunch to the runway anyway.

Using this technique, you may as well toss the performance book's numbers for Landing Distance and LFL out the window, since there is no "Look I'm aerodynamically braking like an F-15" chart to be found anywhere.

Related to this last point as it applies to career insurance, remember that the CRJ has a good Flight Data Recorder, and if for some reason you end up in the weeds beside the runway or off the end, it will tell the story of your "technique" to any interested parties. Don't worry about this however, if your FSM or FOM calls this a normal rollout technique. Correct me if I'm wrong, but I doubt that it does.

It can be uncomomfortable for passengers, especially white knucklers.

IMO, the disadvantages far outweigh any imagined advantages or "pilot appeal" factor.

 

[GCD]

HighSpeed,

You are partly correct, but not completely.

Heating the brakes moderately, as described above with firm steady pressure at 80 knots until a safe taxi speed, is the optimum heat absorption for the brakes. Applying brakes excessively to produce excessive heat acts the opposite. A hot brake cannot absorb heat sufficiently to make a safe stop. That's why there are quick turnaround charts for minimum turnaround time after a landing.

I have worked around Lufthansa, and I am pretty certain that they use reverse thrust. I could be wrong. When I worked for JAL, the Japanese couldn't figure out why the Gaijin (Americans) were landing with cooler brakes than the Japanese pilots. Well, it was because we followed the above procedure, and the Japanese always use Autobrakes in Medium. The company always used cooling fans on the brakes after a Japanese crew made a landing. I used Medium once in a snow storm. It was a lot more braking than I was comfortable with. I never used Max in the real airplane, only in the sim, but that was impressive. The problem is, you have to go to a hazard spot to allow the CFR to watch for an ensuing wheel fire.

Sounds like some horror stories coming forward from keeping the nose up too long. Remember, mains down, nose down, reverse, brakes.

 

[SkyWestCRJPilot]

This is a great thread. My personal technique is to gently lower the nose wheel soon after touchdown. I've flown with pilots who let it slam down right after the mains, and I've flown with ones who like to hold it up and let it fall after the elevator loses its effectiveness. I don't like either of those methods personally. I liken landing the CRJ to landing an airplane twice, first on the mains softly, and next lowering the nose softly. I flown with a lot of guys who just grease on the mains and then forget the nose is still flying and let it just slam down hard. It kind of ruins a good landing not to mention the other reasons others have previously stated for not holding the nose up too long.

I don't even touch the brakes till below 80 knots and then just barely so that when I reduce the reverses the airplane won't lurch forward. Most of the time there always is enough runway. There have been a few times when I've gotten on the brakes early, but that was because I screwed up and floated way down the runway using up precious stopping distance.

 

[logolight]

I think the problem is that there's no performance data or standard training technique that I know of that supports the correct way to rollout an RJ except for the use of the TR's. Once the mains are on the ground, lowering the nose down to the runway correctly is a grey area safety wise. The slow speeds that I'm talking about are well above the low speed barber pole where there is still plenty of rudder effectivenes. I've never landed at an angle so high that I had poor foward visibility, and the breaking margins for incursions etc. are marginal since the nose is only inches off the ground.
Where the problem lies is when tower tells you to "keep the speed up and roll to the end" at which point you are at a high taxi speed and not only cutting down on the reaction time for things like incursions, but you're also running out of available pavement to stop if you suddenly lose your breaks. I do agree with you CatYaak that there are all kinds of possible dangerous situations during the takeoff and landing roll. Thats what this discussion is about.

In my opinion, land the plane, slow it down, and get it under control.



Snooch to the Nooch!

 

[freightdogfred]

Interesting thread.....It's seems more on technique than what's "correct". I don't fly RJ's, but I jumpseated in a few, pre-911. We were halfway down the Macey arrival into ATL before I figured out where the airspeed indication was. It did'nt seem to have a high ref speed, so if the profile was flown correctly I think a good pilot could make the second high-speed on 8R without using brakes or reverse.

Runway analysis is predicated on max braking, no reverse. If you are going into a tight (short) strip, the sooner you get the nosewheel on the ground and apply brakes, the better your chances for stopping on the runway become. Runway clutter merely exacerbates the situation. Reverse thrust is a bonus, and is not considered in the data. Aerodynamic braking, three point landings, no spoilers,etc. are technique, employed when actually stopping distance is not a factor.

I used to fly DC-3's with Goodyear disc brakes. (They would fade rapidly with heat.) One guy I flew with would push forward on the yoke after touchdown, with the tailwheel still in the air. He called it "Aerodynamic braking". It took all day to get that seat cushion out of my ass.

It's common sense- if you need the brakes, use them. The slower the A/C is going prior to application, the less they will wear. This applys to the space shuttle or a C-150.

 

[GCD]

FDfred,

If you were j/s in a Canadair RJ, it was a very light one.

Typically, Vref + factor = 140's for a target speed on final.

The CRJ's final approach speed is similar to the B747's. The big difference is, that I can vector around slower in a 747 than I would feel safe to do in the CRJ. Especially in icing conditions.

The lumbering giant has leading edge flaps and trailing edge flaps that create a huge wing surface. The Canadart has a hard, thin wing without LE devices. Thus the 3' nose low attitude on final.

That is one of the resons I started this tread. The Canadart has a very fast fence speed, and puts high demands on the airplane's stopping systems.

I do agree with you, FDfred, the slower you are when you apply the brakes, the longer they will last.

 

[abev107]

this is a great thread! I enjoy it when you folks share a philosphical discussion on technique, etc...