Thrust
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777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 7:23 am

Both times that I flew a 777, which was for AA, I noticed that the landing was different than any other type of aircraft before it. For some reason, the roar that we typically hear when the thrust reversers of an aircraft are applied on the runway was not present with the 777. The only thing I heard and felt was the thump of the landing gear on the runway and the aircraft slowing down...the noise literally remained the same the whole way through the landing...you could've sworn that the aircraft was still flying. Anyway, getting to my question, I wanted to know what in the world makes these thrust reversers add little or no noise to the aircraft when deployed on landing? How on earth can such powerful engines be so quiet on landing?
Fly one thing; Fly it well
 
DfwRevolution
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 7:25 am

AA might not have been using reverse thrust on your particular flight. B6 does this as well to reduce community noise and some engine wear at a few airports.
 
Klaus
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 7:40 am

I remember an explanation given earlier by pilots that they frequently deploy the reversers without revving up the engines again ("idle reverse"). That would give only marginal braking assistance (so the brakes have to work harder), but there is much less noise to the environment than in "full reverse". It seems many airports recommend this mode of operation for their neighbours´ sake.
 
goboeing
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 8:21 am

It is an SOP to use reverse thrust at most airlines / aircraft with them. It may have been unlocked and put in idle, but it was at least there, ready to go to full reverse thrust if it was needed.

Nick
 
SimProgrammer
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 9:29 am

Thrust:

Was this a late night or early morning landing?

UA and BA's 777's deploy reverse thrust and can be adequately heard, but during unsociable hour landings many airports don't allow reverse thrusts to be deployed or excessive thrust during taxi.
Drive a bus, an Airbus, easier than a London bus!
 
cdfmxtech
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 9:43 am

The B777 is equipped with carbon brakes. Carbon brakes are much more effective when they are heated up. For this reason, the Thrust Reversers are deployed, but left in Idle reverse. This can extend the life of the engine (less High EGT ) and decrease the chances of FOD damage.
 
cancidas
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 10:57 am

don't forget, it's not reversers that stop airplanes, it's the brakes.
"...cannot the kingdom of salvation take me home."
 
JeffDCA
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 11:18 am

Having flown on a fair few 777's (including AA) it seems to me that on both of your flights reverse was simply not used. You can hear it just as much as on any other aircraft, even if at idle reverse.

Cheers,

Jeff
If something hasn't broken on your helicopter, it's about to.
 
lorm
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 12:46 pm

If there's a long runway, it's not high traffic hour, and the 777 you're on doesn't need to vacate the runway early, chances are they won't use reversers. Like the replies above, the 777 has very effective carbon brakes. I remember the first time I flew on the 777, landing in ORD several years ago, I was so surprised that landing on 22R we never utilized thrust reversing.

My last 2 trips in June, on legs flown with the 777 we used thrust reversers once. On my ORD-SFO on UA137, that leg we flew an international equipped 777 and I was seated in 1J in F/C. Upon landing on 28R I could hear only slightly the wind noise from the cascades opening up. Sometimes it is less obvious if you're sitting up front ahead of the engines.

Last leg to HNL on UA61 which arrived around 4pm, we landed on 4R, not commonplace as usually before 630p, the majority of heavy jet traffic lands on 8L. Anyways on 4R the normal practice is to roll down to the end and then do a turnoff, which we did without reversers deployed. Still with 9000' of runway we were out of autobraking and coasting before we crossed 8L, so we easily slowed down even with a full load of passengers. I had to sit near the engine at 22J  Crying and even idle reverse wasn't used.
-Mike
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Aaron747
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 2:35 pm

I flew AA SJC-NRT and back last March, and noticed this upon arrival. We came in on 34L on a rainy day and touched down a bit long but still didn't use anything more than idle reverse. 34L/16R has at least 11,000' of landing distance though so we simply braked for a bit and exited one of the high speeds for the short jaunt to the terminal.

Coming back to SJC however, we were hot the whole way down to 30L and came down a bit long. There was definitely reverse thrust applied as we slowed *very* quickly.
If you need someone to blame / throw a rock in the air / you'll hit someone guilty
 
modesto2
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Aug 19, 2004 10:53 pm

Dfwrevolution, Jetblue (like most airlines) always uses reverse thrust. However, most flights will keep it at "idle reverse" and nothing more.
 
star_world
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RE: 777: Why No Noise When Thrust Revers Applied?

Sat Aug 21, 2004 5:40 pm

I've noticed this many times at LHR in early mornings, I usually leave my car in the car park right next to 27R - probably only a few hundred metres from the runway itself. I've seen 777s land right next to me with virtually no noise - quiet enough that you probably wouldnt notice it unless you were looking! They always had the thrust reversers deployed, but with just idle reverse in use.
 
Thrust
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RE: 777: Why No Noise When Thrust Revers Applied?

Sun Aug 22, 2004 3:51 am

I must confess, SimProgrammer, my first route on a 777 was on AA, BOS-LHR. We touched down at LHR at about 6:00 A.M. in the morning London time. But strangely enough, when I flew LHR-JFK like a week later, we landed at JFK during a perfectably sociable hour, like late afternoon or early evening, New York time. the second landing was no different from the first other than that we were landing at JFK instead of LHR.
Fly one thing; Fly it well
 
beachthing
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Sep 02, 2004 5:43 am

starworld: the image of 777s silently landing in th early morning: what a pretty thought! Love that plane.
 
Thrust
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Sep 02, 2004 2:53 pm

Yes, the 777 is truly a magnificent beast...you have to fly it to believe it  Big thumbs up
Fly one thing; Fly it well
 
ba299
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RE: 777: Why No Noise When Thrust Revers Applied?

Thu Sep 02, 2004 10:21 pm

Often you don't heard the T/R because we use it only at idle. Using the autobrakes the aircraft stop in the same distance with o without reverses. So we prefer (when we can) to avoid the use on the reverses for noise abatement and for more comfort of the paxx.

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