lke2fly
Topic Author
Posts: 52
Joined: Tue May 03, 2011 3:47 am

### Steering An Airliner

My question is while a airliner heads down the runway at full speed before take off at what point does the rudders take over the tiller for control of the airplane in steering straight? Like wise on landing. Thank you

Mir
Posts: 19383
Joined: Mon Jan 05, 2004 3:55 am

### RE: Steering An Airliner

The tiller isn't used at all once the airplane is lined up with the runway for takeoff - the rudder pedals offer enough nose wheel control (and, at higher speeds, rudder control) to keep it on centerline. Same thing during landing, until you're slowed down and ready to turn off the runway - then you start using the tiller.

-Mir
7 billion, one nation, imagination...it's a beautiful day

roseflyer
Posts: 9605
Joined: Fri Feb 13, 2004 9:34 am

### RE: Steering An Airliner

The nose wheel has about eight degrees of travel with using the rudder pedals. This keeps the airplane in line until rudder authority takes over. The transition is at about 60 knots. However there is no hard transition point so it depends on weight and balance and runway friction.
If you have never designed an airplane part before, let the real designers do the work!

KAUSpilot
Posts: 1662
Joined: Mon Jan 28, 2002 2:15 pm

### RE: Steering An Airliner

On the 747 the rudder pedals have no effect on nosewheel steering; therefore we are instructed to use the tiller up until 30 knots groundspeed; beyond that only the rudder should be used.

KAUSpilot
Posts: 1662
Joined: Mon Jan 28, 2002 2:15 pm

### RE: Steering An Airliner

Correction to the above post, the pedals do provide 7 degrees of steering on the 747.

wn700driver
Posts: 1475
Joined: Wed Aug 29, 2001 10:55 pm

### RE: Steering An Airliner

 Quoting KAUSpilot (Reply 4): Correction to the above post, the pedals do provide 7 degrees of steering on the 747.

Just for the nosegear or also for the steerable mains as well?
Base not your happiness on the deeds of others, for what is given can be taken away. No Hope = No Fear

LimaFoxTango
Posts: 848
Joined: Wed Jun 16, 2004 11:33 pm

### RE: Steering An Airliner

The Dash 8 rudder pedals gives 7 degrees of nose-wheel steering.
You are said to be a good pilot when your take-off's equal your landings.

KAUSpilot
Posts: 1662
Joined: Mon Jan 28, 2002 2:15 pm

### RE: Steering An Airliner

Just for the nosegear.

What I was trying to say in my original post was that the rudder doesn't give you additional steering over what the tiller provides; for example in some planes the rudder pedals give you 7 and the tiller gives you an additional 70 for a total of 77. That's not the case on the on the 747. Anyway, body gear steering only kicks in when when the nosegear is deflected more than 20 degrees, so the rudder pedals alone won't trigger it.

B747FE
Posts: 217
Joined: Mon Jun 21, 2004 11:09 pm

### RE: Steering An Airliner

Actually both of your posts are correct. Many 747 classic didn't have rudder pedal steering.

 Quoting wn700driver (Reply 5):Just for the nosegear or also for the steerable mains as well?

Only for the nose wheels.
Steering on the body gear is armed when the nose wheels are turned more than 20 degrees.
And it's not active nor intended to use during take off.

Light pressure on the control column + rudder pedal steering is used at the beginning of the take off roll. Rudder becomes effective above 40 to 60 knots. Until then, the captain always keep left hand on the tiller.

 Quoting RoseFlyer (Reply 2):However there is no hard transition point so it depends on weight and balance and runway friction.

Regards,
B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"

HAWK21M
Posts: 30014
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Steering An Airliner

Just related......
On a B777.....Does mvmt of the Tiller move the MLG in addition to the NLG steering or is it only the NLG that is steered.
I may not win often, but I damn well never lose!!!

SAAFNAV
Posts: 434
Joined: Wed Mar 17, 2010 5:41 pm

### RE: Steering An Airliner

On the C-130 there isn't a link between the nose gear and the rudder pedals.

During the Take-Off Run, the Pilot has the rudders, tiller and throttles, while the Co-pilot has the yoke.

Pilot will open the throttles, using the tiller to keep on center-line, until the rudder becomes effective. Not sure, but I think its at about ~50Kts.
Co-Pilot is keeping the wings level, countering for crosswind as needed.

At 80Kts, the Co will call out 80Kts, Pilot moves his hand over to the yoke, and it becomes his aircraft.
This is practiced excessively in the sim.

Landing is the opposite..
But, it becomes hairy when the co-pilot is landing, as he has to transfer control to the pilot. Unfortunately, some stop flying as soon as the they cross the runway, leaving the pilot with a heck of a workload to go straight.

Erich

Starlionblue
Posts: 17961
Joined: Fri Feb 27, 2004 9:54 pm

### RE: Steering An Airliner

 Quoting SAAFNAV (Reply 10):But, it becomes hairy when the co-pilot is landing, as he has to transfer control to the pilot. Unfortunately, some stop flying as soon as the they cross the runway, leaving the pilot with a heck of a workload to go straight.

The DC-9 and MD-80 only have a tiller on the Captain's side, so you have the same handover if the first officer is PF. Same on many aircraft.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

yeelep
Posts: 740
Joined: Mon Apr 04, 2011 7:53 pm

### RE: Steering An Airliner

737 also has Captain's side tiller. F/O tiller is optional.

tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

### RE: Steering An Airliner

 Quoting HAWK21M (Reply 9):On a B777.....Does mvmt of the Tiller move the MLG in addition to the NLG steering or is it only the NLG that is steered.

MLG steering comes from NLG steering commands, but you have to move the NLG far enough to get it gong. Rudder pedal commands don't move the NLG far enough to get the MLG going, and even smaller tiller inputs won't get the MLG going.

Tom.

LimaFoxTango
Posts: 848
Joined: Wed Jun 16, 2004 11:33 pm

### RE: Steering An Airliner

 Quoting KAUSpilot (Reply 7): What I was trying to say in my original post was that the rudder doesn't give you additional steering over what the tiller provides; for example in some planes the rudder pedals give you 7 and the tiller gives you an additional 70 for a total of 77. That's not the case on the on the 747. Anyway, body gear steering only kicks in when when the nosegear is deflected more than 20 degrees, so the rudder pedals alone won't trigger it.

Wasn't doubting you. I was referring to the DHC8 100-400 not, 747-8.
You are said to be a good pilot when your take-off's equal your landings.

KAUSpilot
Posts: 1662
Joined: Mon Jan 28, 2002 2:15 pm

### RE: Steering An Airliner

No worries, I actually meant to include wn700driver in the quote for my second post since he had asked about body gear steering, hit the wrong button, doh!

HAWK21M
Posts: 30014
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Steering An Airliner

 Quoting tdscanuck (Reply 13):MLG steering comes from NLG steering commands, but you have to move the NLG far enough to get it gong.

How exactly does the MLG steer.....Is it sensed by the directional variation of the Aircraft.....
I may not win often, but I damn well never lose!!!

Posts: 1566
Joined: Fri Feb 22, 2008 7:42 pm

### RE: Steering An Airliner

Is differential braking used at all?
Anon

Starlionblue
Posts: 17961
Joined: Fri Feb 27, 2004 9:54 pm

### RE: Steering An Airliner

 Quoting HAWK21M (Reply 16):Quoting tdscanuck (Reply 13): MLG steering comes from NLG steering commands, but you have to move the NLG far enough to get it gong. How exactly does the MLG steer.....Is it sensed by the directional variation of the Aircraft.....

The mains on the 747 (two bogies only) and 777 (rearmost axles only) steer automatically (unless the function is locked out) once the tiller is deflected beyond a certain amount of degrees. Transparent for the pilots.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

B747FE
Posts: 217
Joined: Mon Jun 21, 2004 11:09 pm

### RE: Steering An Airliner

Sometimes, on very slippery surfaces.

Regards,
B747FE.
"Flying is more than a sport and more than a job; flying is pure passion and desire, which fill a lifetime"

HAWK21M
Posts: 30014
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Steering An Airliner

 Quoting Starlionblue (Reply 18): The mains on the 747 (two bogies only) and 777 (rearmost axles only) steer automatically (unless the function is locked out) once the tiller is deflected beyond a certain amount of degrees.

But whats the principle of operation like......How does the rear axle deflect,by what signal...the tiller or the turn mechanically.
I may not win often, but I damn well never lose!!!

KAUSpilot
Posts: 1662
Joined: Mon Jan 28, 2002 2:15 pm

### RE: Steering An Airliner

On the 744 the nosewheel and body gear steering are all hydraulic, the gear are turned hydraulically by hydraulic system #1. The movement of the body gear is initiated only after the nose gear exceed 20 degrees of deflection from center.

Copied and Pasted from the 744 manual:

 Quoting Boeing:Body gear steering operates when the nose wheel steering angle exceeds 20 degrees. This reduces tire scrubbing and lets the airplane turn in a minimum radius. Body gear steering is activated when ground speed decreases through 15 knots. As speed increases through 20 knots, the body gear is hydraulically centered and body gear steering is deactivated.

HAWK21M
Posts: 30014
Joined: Fri Jan 05, 2001 10:05 pm

### RE: Steering An Airliner

 Quoting KAUSpilot (Reply 21): The movement of the body gear is initiated only after the nose gear exceed 20 degrees of deflection from center.

Thanks....Exactly what I wanted to know....
I may not win often, but I damn well never lose!!!

lke2fly
Topic Author
Posts: 52
Joined: Tue May 03, 2011 3:47 am

### RE: Steering An Airliner

Thank you to all of for educating me on how the rudder and tiller function together on take off and landing.

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