Thrust to flare? 737
 

I've seen this technique a few times now with different pilots:

A few feet off the deck in the flare, the pilot jams the T/L forward and pulls it back just as rapidly. It wasn't for a gust, just for. . . ?

I can think of a few reasons not to do this. Can anyone come up with a good reason to do this? 737CL-NG.

What type of a/c ? T-tail with tail engines or under wing engines?

B737 Classic and NG.

Technique for the 727.

Thanks for the ideas.

Hmm. One or two might have been former 727 drivers. Seems like some of the shorter fields, that won't help matters at all.

Why on the 727? Vertical component of thrust to soften the touchdown? Why not just flare with the yoke?

Probably fodder for a separate thread, but the 727 had a reputation for hard touchdowns if power wasn't kept up through the flare. A whole separate "Tech-Log" debate in itself, but one of the reputed reasons was that the massive triple-slotted flaps could kill airspeed so fast that an unpowered flare simply turned into a 5-foot free-fall.

http://www2.tech.purdue.edu/at/cours...es/727flap.jpg

I guess it depends on which market one is flying in, but it would surprise me if there were many 727 pilots still transitioning to 737s (and bringing along old habits) at this late date.

Brings back the stories I had been told that a single notch flaps would improve cruise performance in a 727? Only damb aircraft I had ever shimmed the I/B and O/B flaps for low speed and high speed aileron trim issues.

Watched a few guys do it on the DC9 - but a quick dab of stab trim worked just as well without the theatricals...
As stated tendency to counteract running out of energy in the flare - had similar on the early Twin astir - grob 109 glider - and had to half retract the airbrakes for the flair.

Used the technique when a high sink rate has developed just prior to touchdown, works wonders! However, routine use????

As you said, if you need it to counter a high sink rate close to the ground fine, otherwise it's a bad habit and can lead to other problems one of which is running out of runway !


Barring a last minute high rate of sink requiring power you will always get a better landing touching down with idle thrust.


And that includes the B727 :ok:

I loved every hour of my 5,000 hours as a skipper of best airplane Boeing built (MHO of course). I sure miss my F/E too. But life goes on.

The 727-100 series does not need the punch of thrust beforetouchdown as the stretched 727-200 needs. The -100 series is an extremely well balance jet aerodynamically speaking. Like a light twin one can chop the power,flare and make a normal landing within the 1,000’ runway markings with consistency.

The 727-200 has much different characteristics during theespecially during the last 50' of the landing phase. If one flares the jet withback pressure, the mains will be driven onto the runway as the center of liftis forward of the mains. It’s takes acoordinated effort to make a proper landing… a punch of thrust to help check the decent, and actually abit of forward pressure to ensure a nice touch down. No float and always within 500’ of the 1,000’marker. A nice feature about the 727 is when the power comes off thejet does not float like the 737.
I used the same technique with airports with 5,300’ runways inthe Caribbean and Tegucigalpa before they blew off the top of the mountain southRunway 02 which now has about 5,500’ of useable runway beyond the threshold.

Quote:

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Barring a last minute high rate of sink requiring power you will always get a better landing touching down with idle thrust.

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That said, Stilton, many -200 drivers and MD80/90 pilots may not agree with your assertion.

The 727-200 does not need a burst of thrust in the flare. I have heard of this technique and it may work, but it can be landed just fine by doing a normal approach and landing(admittedly mine were all flaps 30). Bring the thrust off in the flare. Seem to remember that it was at about the 20 foot autocall. Most landings were decent, some were firm and some were greasers. Some guys flared and then pushed a bit, some on occasion just gave a forward push on a short runway(good for spot landing but you knew when you touched down). Sometimes just a normal bit of a pull worked as well.

It certainly was not a requirement to add a burst of power to get a normal landing with flaps 30.

I should have made a clarifying statement that the burst ofthrust was a technique I adopted. As theold saying goes “whatever works…”

The "burst of power" addiction (and believe me it is an addiction) is common to many pilots flying the 737. These pilots have picked it up from watching other pilots or listening to war stories from olde captains who may have flown the 727. From these myths they then think it is a real cool method of getting a smooth touch down.

Interestingly, you don't see much of this technique in the simulator yet it is relatively common among certain pilots in the real aeroplane. Inevitably the aircraft floats and lands long, albeit often smoothly. That makes the pilot real happy and he is now convinced for the rest of his career that a burst of power is the key to smooth landings.

Other new pilots watch him and the technique is perpetuated. Of course there are times when additional power is called for near the flare but it is not a standard technique for normal landings and needs to be severely discouraged as bad flying technique

I'm guessing that JT-9D have a much quicker spool-up and -down time than a CFM-56.

A "short jab" on the JT-9D might be more of a "slow swipe" on the CFM-56.

Either way, the last guy I flew with grumbled, "Damn -900s" as we limped off the runway. No softening about it.

Captjns


Seven years on the B727 and four on the MD80.


Idle thrust at touchdown was the flight manual procedure and, to reiterate, unless power was required to correct a high sink rate always resulted in a better landing.


Some may disagree but these were the guys I saw porpoising down the runway with their experimental homemade techniques.


They never got a predictable result but they used up a lot of runway believing in a myth these Aircraft could not be landed like any other jet transport.

there are some reasons, good or not is up to you.

1. when you jam on thrust what happens on a 737? the nose goes up...underwing engines will push nose up ...cutting power brings nose down

2. Airplanes get bent up in real life...wing leading edges get roughed up in real life...if you cut power too soon the drage may make the plane slow down a bit faster than the ''ideal'' brand new plane or simluator.

3. Here is a real help...if you and the engines are spooled up just at touchdown, they will be more available for reverse thrust...in other words jam up the throttles, engines spool up and retard them allowing reverse thrust selection and the reverse thrust is available more quickly as the engines are still spooled up

4. It is possible the pilot is adding the thrust because he has perceived a high sink rate developing and you haven't

6. notice I missed five?

5. I've flown botht the DC9 and 737. DC9 is my favorite. and a quick burst of power is used when a high sink rate develops near the end, usually if the airfield is blanked by trees, cutting off the wind or if there is windshear for other reasons. judging sink rate can be a very ''seat of the pants'' thing.

so ask yourself if the pilot is doing it at fields where the trees blank the wind

For the "long" 737 like the 800, 900 (and even the 300 maybe) the flare is sensitive and that's not easy to decrease the sink rate below 200/150 ft per minute (that should give you a standard load) with flaps at 40, but quite easy if you keep some thrust til touch down. Thing is keeping thrust during touch down is not standard procedure for many reasons, one being, for example, that the speed brake won't deploy automatically, so one method is the one you mention, it gives you thrust during touch down (the engine don't have time to come back to idle) while the thrust handle is at idle and the speed brake will deploy with a lower pitch up attitude that should prevent any bounce.
However the ones able to master this non standard technique are the ones already confortable with the standard, normal flare. Useless then at the end.

Looking outside too...

As I posted before Stilton... it was my technique. Just a burst of thrust to arrest the decent and off for the touchdown. No float, and no porpoise down the runway. By the grace of the Sky Gods, I never ran off the 5,500' runways I operated into. At least the good old 727 has normal approach speeds and powerful brakes versus newer generation jets of today. I will say this however, getting out with -9s could be a challenge at times... but that is a topic for another thread.

I've never seen jets test flown to or from short runways, and as Joe Petroni said, "Good thing the B707 can't read.". Well either could the 727.