Difference between flare out and round out?

[Sahil Ali]

Kindly please any one can explain the difference between flare out and round out while landing an aircraft?

[fireflybob]

Just "flare" or "roundout" - same thing.

[Sahil Ali]

So flare/round out is the stage when u cut power to hold your aircraft above the runway by giving checks. Do airliners cut power to idle too as they do on small aircraft at flying clubs or they usually go for powered landings. How much power do they keep?

[de facto]

As we pull we reduce the thrust,,,if you increase the lift but keep the same thrust you aint going where you are supposed to.
If not on ground by the time the thrust is idle,the energy from thrust into your elevator will be released (pilot) and aircraft will settle.

[Fly4Business]

It's been a long time since I heard the term round out ...

In my training, long time ago, I learned that "flare out" is the whole transitioning from a stable approach to touch down on the runway, followed by "taxi". Just looked up my old notes and "flare out" was: do the landing check, get mentally ready to land (or "do not land" for beginners to get the flare right), grab yoke and disengage AP if used, reduce power further, round out, hold steady and pull slowly back, let the aircraft float, wait for the plane to settle gently to the ground, fetch the touch moment and use controls appropriate. So for my training with a very precise instructor "round out" was only the small part in "flare out", where you transition from stable approach to landing attitude. I doubt precision is a value today, as everybody got lazy, so most of the times I heard it later, the two were used as the same. Also, many airliners are flown to the ground not let settle to land, so difference is little.

And no, airliners and jets do not pull to idle in landing and the amount to stay is a matter of the operational procedures, mostly set by the manufacturers of the plane and the engines, plus some input from the operator. The reason for not pulling back to idle is a better handling and most important, preparedness for go around. Turbines need a certain time, much longer then pistons, to spin up and produce thrust, so to ensure the possibility to go around you have to have a certain power already at the engines. Actual percentage varies from plane to plane and maybe even from operator to operator.

[de facto]

And no, airliners and jets do not pull to idle in landing and the amount to stay is a matter of the operational procedures, mostly set by the manufacturers of the plane and the engines, plus some input from the operator. The reason for not pulling back to idle is a better handling and most important, preparedness for go around. Turbines need a certain time, much longer then pistons, to spin up and produce thrust, so to ensure the possibility to go around you have to have a certain power already at the engines. Actual percentage varies from plane to plane and maybe even from operator to operator.
Not sure i am following you....are you saying airliners touch down with thrust above idle is the norm?

[Chesty Morgan]

Depends which idle you're thinking about.

[barit1]

There are a couple idles that may apply:

o Flight or descent idle - fairly low RPM for best descent

o Approach idle - for high drag (gear & flaps out)

o Ground idle - min thrust to save brake usage

Usually these are automatically selected in the airframe circuitry. There are different acceleration times (cert. specs) for each condition. And there may be newer terminology that the current guys can update.

[barit1]

Sahil Ali - You didn't specify turbine vs. piston powered aircraft, did you? And associated with this, how long is the runway compared to the aircraft requirements?

[parkfell]

Light pistons : start the flare / round out and by doing so the rate of descent will reduce. As you start to select the landing attitude, close the power smoothly so that you are at idle setting prior to touchdown.

Turbo prop : depending upon the type, you may well have in a hint of power on touchdown due to discing props. Depends really what the set up is. Close the throttles immediately when the back wheels touch. This was true of the Saab340. The AFM talked about close the power at 10ft. This would result in a firm arrival.

Jet : close the thrust levers prior to touchdown, otherwise the spoilers will not deploy ~ aka B.737
Mr Boeing says you fly it on with a small rate of descent; avoid floating and use up valuable runway.
The spoilers will dump the lift, put weight on the wheels, and braking will be effective.
You simply must not float otherwise the performance calculations are jeopardised, big time

Fly4Business : I would be interested to know which specific types of jet require power on touchdown. I presume we are not talking about the F14 tomcat landing on a deck?

[Piltdown Man]

I believe that the round-out or flare is the pitch change from the one used on approach to the one required in the hold off, the brief period of time when you fly parallel to the runway surface. Long extended flares are generally best avoided (for performance reasons) and generally should not be possible if you have flown your approach at the proper speed. Adding a few extra knots for your soon to be orphaned kids is not a good idea.

But as I'm here, I too would like to know which jets, and turbo-props come to that, require anything other than some form of idle thrust to land. Every jet and turbo-prop I know requires idle thrust and only very brave operators The actual value of thrust selected depends on the type. For some it means Flight Idle, for others Approach Idle; Ground Idle being selected when allowed by weight-on-wheel switches and possibly a further selection by the pilot.

PM

[Chesty Morgan]

Q400 for your TP other wise it's like lobbing a shopping trolley off Tesco's roof.

[de facto]

Depends which idle you're thinking about.
Those are automatically controlled and irrelevant since the OP was mentionning to keep thrust ABOVE idle.("reasons for not pulling back to idle").

[barit1]

How not to do it:

ASN Aircraft accident Boeing 737-7H4 (WL) N753SW New York-La Guardia Airport, NY (LGA) (http://aviation-safety.net/database/record.php?id=20130722-0)

Nose gear only on the r/w - very directionally unstable, like a taildragger, only worse! :eek: