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Thrust Reversers Before Touchdown?  
User currently offlineDocLightning From United States of America, joined Nov 2005, 19416 posts, RR: 58
Posted (6 years 3 weeks 2 days 19 hours ago) and read 9806 times:

Check out this video:

http://www.youtube.com/watch?v=VIGtAjjnQbs&feature=related

Look at the thrust reverser deployment. Now, the wheels are CLEARLY off the ground when he deploys them.

Other than "he's a crazy Rusky" why would you do this?

42 replies: All unread, showing first 25:
 
User currently offlineJetstar From United States of America, joined May 2003, 1642 posts, RR: 10
Reply 1, posted (6 years 3 weeks 2 days 2 hours ago) and read 9773 times:
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It looks like they just deployed the thrust reversers, probably landing on a short runway to get them extended and ready for thrust reverse application as soon as they touch down. Normally as soon as you pull up on the thrust reverser levers, the reversers will extend, but it takes pulling up on the reverser levers to increase engine thrust to make the reversers effective.

On the Lockheed JetStar we occasionally did this landing on a short runway, there was no weight on wheels switch or auto reverse thrust, as long as the power levers were back to idle we could deploy the reversers, so as soon as we pulled the throttle levers back to idle just before touch down we extended the reverser buckets and were ready to apply reverse thrust.

Turbine jet engines can have a few second lag from the time of reverser deployment to full reverse thrust, so by getting the reverser buckets out early and even pulling up on the thrust reverser levers the engines would start spooling up and by the time the wheels touched down, enough reverse thrust would be available to start slowing the airplane down as max thrust reverse was applied


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 2, posted (6 years 3 weeks 2 days 2 hours ago) and read 9769 times:
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Quoting Jetstar (Reply 1):
Turbine jet engines can have a few second lag from the time of reverser deployment to full reverse thrust, so by getting the reverser buckets out early and even pulling up on the thrust reverser levers the engines would start spooling up and by the time the wheels touched down, enough reverse thrust would be available to start slowing the airplane down as max thrust reverse was applied

I wonder if such a procedure is officially approved and/or recommended in any flight manuals...

2H4



Intentionally Left Blank
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 3, posted (6 years 3 weeks 2 days ago) and read 9710 times:



Quoting DocLightning (Thread starter):

Other than "he's a crazy Rusky" why would you do this?

As evidenced by the pics this doesn't seem to be an uncommon procedure on the type. I remember Gabon Express did the same on their Caravelle.

The question, as 2H4 says, is if this is approved in the manual.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 4, posted (6 years 3 weeks 2 days ago) and read 9698 times:
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Quoting Starlionblue (Reply 3):
The question, as 2H4 says, is if this is approved in the manual.

Actually, this thread could become very interesting......does anyone here know of a procedure that, while approved in the flight manual, is in your opinion unsafe or unwise?

The only I can think of off the top of my head are rather extreme flap settings in some older 172s and 182s that make landings a bit dodgy when operating at light weights. I think the combination of full flaps and light weights have set a lot of pilots up for nosewheel-first landings over the years.

2H4



Intentionally Left Blank
User currently offlineSashA From Russia, joined May 1999, 861 posts, RR: 0
Reply 5, posted (6 years 3 weeks 1 day 23 hours ago) and read 9691 times:

Seems to be a common thing at least in Russia. Yak 40, Tu 154 and IL62 deploy thrust reverse whenever landing in challending weather conditions to avoid risk of runway overrun (slippery surface etc).


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User currently onlineViscount724 From Switzerland, joined Oct 2006, 24896 posts, RR: 22
Reply 6, posted (6 years 3 weeks 1 day 23 hours ago) and read 9684 times:

The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that.

User currently offlineJetstar From United States of America, joined May 2003, 1642 posts, RR: 10
Reply 7, posted (6 years 3 weeks 1 day 22 hours ago) and read 9632 times:
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Quoting 2H4 (Reply 2):
I wonder if such a procedure is officially approved and/or recommended in any flight manuals...

If I remember correctly, deploying the thrust reversers before wheels touching down was not in the JetStar flight manual, but also there was no prohibition in the manual about not doing it, so I guess it’s a gray area. Also I am only talking about the legacy P&W powered JetStar, not the 731 varsion.


User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 8, posted (6 years 3 weeks 1 day 20 hours ago) and read 9597 times:
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Some aircrafts are certified to use the thrust reverser before touchdown. On most aircraft the thrust reverser won't be operable until the air/ ground sensor on the wheels senses ground. Like on the MD11F. Only when the main wheels are on the ground you will be able to activate the thrust reverser. And thrust reverser number two will only be available for full thust reverse once the nose gear is on the ground (MD11F). Sometimes you see eng #1 and #3 on full reverse and #2 is still on its way to full reverse  Wink

WILCO737 (MD11F)
 airplane 



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User currently onlineStarlionblue From Greenland, joined Feb 2004, 17002 posts, RR: 67
Reply 9, posted (6 years 3 weeks 1 day 15 hours ago) and read 9513 times:



Quoting Viscount724 (Reply 6):
The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that

Yes but not on final approach.  Wink

Quoting WILCO737 (Reply 8):
Like on the MD11F. Only when the main wheels are on the ground you will be able to activate the thrust reverser. And thrust reverser number two will only be available for full thust reverse once the nose gear is on the ground (MD11F). Sometimes you see eng #1 and #3 on full reverse and #2 is still on its way to full reverse

I'm guessing that if #2 deploys before nose wheel touch down there will be a rotating moment in the wrong direction, keeping the nose wheel up longer than wanted.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 10, posted (6 years 3 weeks 1 day 15 hours ago) and read 9510 times:
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Quoting Starlionblue (Reply 9):
I'm guessing that if #2 deploys before nose wheel touch down there will be a rotating moment in the wrong direction, keeping the nose wheel up longer than wanted.

When the main wheels touchdown, all three thrust reverser can be engages in idle. You can move the thrust lever to full reverse thrust, but the FADEC will keep eng #2 at idle reverse until the nose gear is on the ground. then it spools up to full reverse thrust.
And about the moment you are right. To avoid a pitch up moment during or right after touchdown, it is designed like this. Same with the spoilers. with main gear touchdown they come out 2/3rd and with nose gear touchdown they move to full extend...

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineXT6Wagon From United States of America, joined Feb 2007, 3392 posts, RR: 4
Reply 11, posted (6 years 3 weeks 1 day 14 hours ago) and read 9506 times:

The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.

User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 12, posted (6 years 3 weeks 1 day 11 hours ago) and read 9462 times:



Quoting Viscount724 (Reply 6):
The DC-8 is also certified for inflight use of thrust reversers.

As was the HS Trident. It could achieve a decsent rate of ~10,000 fps if necessary, though the FE apparently had to work very hard to regulate the cabin pressure. From memory, I'm pretty sure it was approved on Concorde, too.


User currently offlineCosmicCruiser From United States of America, joined Feb 2005, 2255 posts, RR: 15
Reply 13, posted (6 years 3 weeks 1 day 10 hours ago) and read 9447 times:



Quoting Jetstar (Reply 7):
If I remember correctly, deploying the thrust reversers before wheels touching down was not in the JetStar flight manual, but also there was no prohibition in the manual about not doing it



Quoting Jetstar (Reply 7):
Also I am only talking about the legacy P&W powered JetStar, not the 731 varsion.

Yea, I flew both versions of the Jetstar for about 3 years and we never deployed the reversers prior to tochdown and I don't remember it ever being discussed in grd. school at Marietta nor Flight Safety but then I speaking of 35 yrs ago!!  old 


User currently offlineHAWK21M From India, joined Jan 2001, 31667 posts, RR: 56
Reply 14, posted (6 years 3 weeks 1 day 9 hours ago) and read 9430 times:



Quoting XT6Wagon (Reply 11):
The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.

Are you saying B734.
Why not Air-Grd sense.
regds
MEL



Think of the brighter side!
User currently offlineDocLightning From United States of America, joined Nov 2005, 19416 posts, RR: 58
Reply 15, posted (6 years 3 weeks 1 day 6 hours ago) and read 9346 times:

Quoting Jetstar (Reply 1):
Normally as soon as you pull up on the thrust reverser levers, the reversers will extend, but it takes pulling up on the reverser levers to increase engine thrust to make the reversers effective.

I'm sorry, but this sentence makes no sense. You state that you pull up on the reverser levers to extend the reversers... but then that the same action, yet somehow different, will cause the engines to spool up? I think you made a typo and since I've never flown a plane, I'm not sure what you mean.

Could you kindly clarify?

Quoting David L (Reply 12):
As was the HS Trident. It could achieve a decsent rate of ~10,000 fps if necessary, though the FE apparently had to work very hard to regulate the cabin pressure.

Why is that?

So my other question is that if you deploy the reversers before you cross the threshold and then you get hit by a gust of wind that throws your roll off or something, how are you going to get them stowed in time to do a go-around? He looked to be a good 10 feet AGL when they folded out. And in 2H4's photos, it appears that they are as much as 30-40 ft. AGL with reversers deployed. I know probably nobody here has every flown a Tu-154, but is it really THAT much of a bulldozer to stop?

[Edited 2008-07-09 11:38:18]

User currently offlineWILCO737 From Greenland, joined Jun 2004, 8968 posts, RR: 76
Reply 16, posted (6 years 3 weeks 1 day 6 hours ago) and read 9343 times:
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Quoting DocLightning (Reply 15):
Could you kindly clarify?

he means: you pull on the thrust reverser lever. Then the thrust reverser will be activated, means the doors for the T/R start to open and the flow of the thrust will be reversed. But only idle. During this door opening you can pull on the T/R levers as much as you want, you cannot move them up any further. means you only have idle reverse thrust until the doors are fully opened, then this lock will be removed and you can pull on the T/R levers and adjust it from idle reverse to full reverse...

WILCO737 (MD11F)
 airplane 



It it's not Boeing, I am not going.
User currently offlineLY744 From Canada, joined Feb 2001, 5536 posts, RR: 10
Reply 17, posted (6 years 3 weeks 1 day 5 hours ago) and read 9313 times:

Deploying T/R before touchdown is standard procedure on the IL-62 (where only 2 of the engines have reversers), but I'm not aware of that being part of the Tu-154 SOPs. Of course nothing that a modern Tu-154/Il-86/Il-76/An-12/Tu-134/Il-62 crew does could surprise me anymore.


LY744.



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User currently offlinePoint8six From United Kingdom, joined Apr 2008, 94 posts, RR: 0
Reply 18, posted (6 years 3 weeks 1 day 4 hours ago) and read 9293 times:

Reverse in the air , above 10,000ft, was approved for the HS Trident, as was full reverse in the flare (for short/wet/contaminated runways). I believe it was used on Concorde to reduce speed from supersonic to subsonic. I understand it was used on DC-8s with RR Conways - not sure about other engine types. I have seen it selected in the flare on a B747-400 - fortunately it did not deploy until "weight-on"  Wow!

User currently offlineDavid L From United Kingdom, joined May 1999, 9523 posts, RR: 42
Reply 19, posted (6 years 3 weeks 23 hours ago) and read 9232 times:



Quoting DocLightning (Reply 15):
Why is that?

The example I heard (on TV) was from an ex-Trident Captain who was given an approach slot that required either descending that quickly or joining the back of a long queue. It certainly wasn't routine.  Smile

Quoting DocLightning (Reply 15):
how are you going to get them stowed in time to do a go-around?

Good point. As Starlionblue says, I'm not aware of the other types mentioned deploying reversers at the same point as those Il-62 examples.

Quoting Point8six (Reply 18):
I believe it was used on Concorde to reduce speed from supersonic to subsonic.

Not routinely, though?


User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 20, posted (6 years 3 weeks 18 hours ago) and read 9175 times:



Quoting 2H4 (Reply 2):
I wonder if such a procedure is officially approved and/or recommended in any flight manuals...

It's allowed on all 737NG's from the factory...whether an airline puts that into their flight manuals is another question.

Quoting Viscount724 (Reply 6):
The DC-8 is also certified for inflight use of thrust reversers. I recall several previous threads in this forum referring to that.

Most low-bypass engines with bucket-reversers can be safely deployed in flight without a disaster happening. For high bypass engines with cascade or petal reversers, it's generally a bad thing so it's usually restricted to being on the ground or very close to it (at least on Western aircraft).

Quoting XT6Wagon (Reply 11):
The 737-400 is able to deploy the reversers w/o the wheels down, it uses the radar altimiter to allow/deny the use of the reversers.

All 737NG's can do this too.

Quoting HAWK21M (Reply 14):
Are you saying B734.
Why not Air-Grd sense.

You always want two air/ground inputs to make sure you don't loose reversers if an air/ground sensor goes bad. On Boeing's with multi-axel bogies, they use strut compression and truck tilt as the two inputs. 737's, for obvious reasons, don't have a truck tilt sensor. So they used the radio altimeter as the other input. You can deploy reversers if you're on the ground or if the radio altitude is less than 10'.

Tom.


User currently offlineThirtyEcho From United States of America, joined Dec 2001, 1644 posts, RR: 1
Reply 21, posted (6 years 3 weeks 15 hours ago) and read 9143 times:



Quoting 2H4 (Reply 4):
The only I can think of off the top of my head are rather extreme flap settings in some older 172s and 182s that make landings a bit dodgy when operating at light weights. I think the combination of full flaps and light weights have set a lot of pilots up for nosewheel-first landings over the years.

Take it easy there, Astronaut; the 40 degree flap settings on the early Cessna singles were wonderful if one flew into short or rough runways, especially if one had to dive-bomb over tall trees near the approach end of a short field.

The 182 on landing is nose-heavy, even with NO flaps,
and can be wheelbarrowed by the novice quite easily.


User currently offlineNomadd22 From United States of America, joined Feb 2008, 1832 posts, RR: 0
Reply 22, posted (6 years 3 weeks 13 hours ago) and read 9117 times:

Maybe he was an old Harrier pilot having a flashback.


Andy Goetsch
User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 23, posted (6 years 3 weeks 10 hours ago) and read 9065 times:
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Quoting ThirtyEcho (Reply 21):
Take it easy there, Astronaut; the 40 degree flap settings on the early Cessna singles were wonderful if one flew into short or rough runways, especially if one had to dive-bomb over tall trees near the approach end of a short field.

Hey, no argument here! I've had plenty of fun with flaps40.  yes 

My point was simply that, over the years, that flap setting has set many less-than-disciplined pilots up for very bad days. To them, it's just another flap setting. In reality, it's an introduction to a very different set of benefits and pitfalls...all of which should be considered and respected.

Quoting ThirtyEcho (Reply 21):
The 182 on landing is nose-heavy, even with NO flaps,
and can be wheelbarrowed by the novice quite easily.

Precisely!

2H4



Intentionally Left Blank
User currently offlineMark5388916 From United States of America, joined Aug 2007, 377 posts, RR: 0
Reply 24, posted (6 years 3 weeks 8 hours ago) and read 9032 times:

The C-5 Galaxy Also can deploy T/Rs in flight. IIRC, Its limited to FL240 when the T/Rs are out of service because it won't be able to descend fast enough otherwise..

Mark



I Love ONT and SNA, the good So Cal Airports! URL Removed as required by mod
25 Avioniker : You have both brought up a once popular misconception. Actually it's to keep the nose from slamming down as a result of the heavy deceleration and tu
26 Kalvado : should it be 10 000 fpm? 3000 m/s is way too hypersonic..
27 Bellerophon : Reverse in the air, right down to touchdown, was approved on the Trident. There was no only above 10,000 ft restriction. Having said that, it was ver
28 Nomadd22 : Dang. I was looking forward to that 7,000mph decent.
29 Point8six : There was a restriction on the use of reverse thrust on the HS Trident, during descent and it was a SOP restriction, that it had to be cancelled by FL
30 2H4 : Sorry, I'm not quite clear on this....was the restriction put in place by the manufacturer, or by the airline? Well heck, don't leave us hanging...wh
31 Blackbird : I think it's pretty obvious that the Trident could do a 10,000 feet per minute descent, not 10,000 feet a second. Andrea Kent
32 Metroliner : T/R before touchdown, if an FS2004 manual for a Tu-154M is of any value whatsoever (please do note a raised eyebrow on my part) is supposedly discreti
33 David L : 10,000 feet per Saturday. What's wrong with that? On the other hand... oops! Indeed, I've only heard that one example of the use of reverse for such
34 DocLightning : Aha. Thanksey. I bet it could do 10,000 feet per second. You aim the nose straight down and select full thrust. Pretty soon... ...you win a Darwin Aw
35 Bellerophon : Point8six There was a restriction on the use of reverse thrust on the HS Trident, during descent and it was a SOP restriction, that it had to be cance
36 Point8six : Bellerophon - you obviously still have your Trident manuals -( mine are probably still in the loft of a house I moved from nearly 30 years ago!) and s
37 David L : We're sitting comfortably.. you may begin.
38 JoeCanuck : I saw a show that descent reverse thrust is available on the C-17.
39 Tdscanuck : It wouldn't surprise me...the C-17 can do a lot of things that a commercial jet can't do, primarily to achieve the desired short field performance. T
40 Starlionblue : It is. By using idle reverse and deployed surfaces the C-17 can descend at 15000 fpm if memory serves.
41 Post contains images Bellerophon : Point8six Thanks for the detailed reply, I'm glad it was you and not me, as it must have been quite worrying for a while. The impartial management inv
42 Point8six : You flew the Trident simulator voluntarily, until recently? I'm sending the men in white coats around.
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