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boardnick
12th Apr 2005, 17:53
Hello All,

I had a conversation with someone about landing a 757 and they said that it is fairly common practice to land with the left wing a little low. The reason stated is that in the left main landing gear there is a switch which actuates the spoilers, so encouraging the left MLG to contact first helps stabalise the aircraft as the braking begins.
Can anyone tell me if this is a recommended technique (official or unofficial!) or a complete load of garbage.
Many thanks.

haughtney1
12th Apr 2005, 18:15
Dunno about the left wing low malarcy....but I was taught 30 ft check and flare...20 feet close thrust levers....and gently does it...

Then when your really good.....drop everything by 10 feet..i.e check flare at 20 feet..close thrust levers at 10 feet. Dont forget to fly the nose wheel onto the runway..otherwise she will bite..with a thump!

beamer
12th Apr 2005, 18:39
To use your own expression - 'a load of garbage' - I don't know all the answers but have been flying the 757 for about nine years now !

Jetstream Rider
12th Apr 2005, 18:46
You can land left wing down - sometimes dropping one gear first helps in a crosswind, but not really. Better to get both sides down at the same time - it feels better and makes no perceptible difference with the speedbrakes. If you land exceptionally smoothly, sometimes the only indication you are on the ground is the speedbrakes coming out. Haven't done that too often though!

I find landing a 75 as described above works well, but now I use the radio callout as a guide and judge it all by visual picture. A number of times the 75 has shouted "50" at me when we have been at about 70 feet, if you trust it you end up messing up a nice approach.

In a cross wind with proper coordination of controls you will land pointing in the right direction and with both sides together. If you have any drift on, the aircraft will shake just after touchdown which can be uncomfortable. If you have it lined up exactly with the runway, this does not happen. Insufficient aileron on a crosswind landing will mean one side touches first, but if you put enough in, that won't happen.

shlittlenellie
12th Apr 2005, 18:50
Garbage.

Automatic spoiler deployment requires both main landing gear trucks to un-tilt together with idle thrust.

Bealzebub
12th Apr 2005, 18:53
It may well be the case if the observer has been on flights with a marked crosswind from the left, otherwise the premise and the reason suggested is indeed " a complete load of garbage".

boardnick
13th Apr 2005, 09:14
Thank you to everyone who has replied, you have been a great help.

JackOffallTrades
13th Apr 2005, 21:33
pull back, close thrust levers, close eyes and wait....:}

Jo90
14th Apr 2005, 08:19
Rudder wise treat every landing as a Xwind to avoid the shimmies.
For a smooth touchdown relax the back pressure on the column slightly just before main wheel impact.

Kolibear
14th Apr 2005, 08:53
All pilots land left wing low, because they are sitting on the left. If you watch a sequence of aircraft landing, in about 80% of landings, the left wheel will touch first.

Gazeem
14th Apr 2005, 09:04
Ah, I see the logic, what if the FO is flying?

Does it land on the right wheel first!

Does that mean that 80% of captain's don't let their FOs fly??

:p

Boeing 7E7
14th Apr 2005, 09:08
And of the 50% of 757 pilots that sit on the RHS...?
Give me stength!

BN2A
15th Apr 2005, 14:12
And if you're carrying a training pilot in the observers seat, does it land nose wheel first???:p

Kestrel
15th Apr 2005, 14:43
The switch is on the nose/main gear which activates very early in compression during landing/ first contact.

Bealzebub
15th Apr 2005, 15:22
Not so Kestrel,

The spoilers are ( in the armed position) fully extended and the lever driven to the up position, when the main gears are untilted and the thrust levers are at idle. Failing this they are also extended when either reverse thrust lever is moved to the reverse idle detent, provided again the main gear trucks are in an untilt condition. In the latter case the speedbrake lever does not need to be in the armed position.

The nose gear A/G compression sensing logic is used for controlling stall warning and portions of the caution and warning system.

As I See It
15th Apr 2005, 15:43
Not so Bealzebub!

Are you suggesting that you could apply reverse thrust with the nose wheel in the air, not so, below is the AMM32-09-02 reference for air ground sensing:

When the airplane takes off, the air/ground relays change some of
the systems from the ground mode to the air mode. The opposite
procedure occurs when the airplane makes a landing. The change
between the flight mode and the ground mode occurs through the
inputs of these sensors and switches and their related electronics:
(a) The truck tilt sensors of the main landing gear.
(b) The not compressed sensors of the nose landing gear.
(c) The pressure switch for the shuttle valve on the truck
positioner.


Remember, it's only As I See It, oh and Boeing as well! Oh yeah and Kestrel too

haughtney1
15th Apr 2005, 16:12
Just a thought.......as PF...by the time your'e selecting reverse, you will have had to fly the nosewheel onto the runway in any case.
As I see it...I didnt believe Beazlebub was suggesting reverser deployment before the nose oleo is compressed, further to this...as you well know with the spoilers armed and thrust levers closed....the spoilers (as a normal part of system logic) will extend...destroy the lift aft of the C.P. and hence cause a small but not insignificant nose down moment...all done to reinforce the process of tilt/compression and consequently activation of thrust reversers.

As an interesting note...in my B757 FCTM..and technical manuals, I can find no reference to the nose oleo/thrust reverser relationship.

(just goes to show that with Pilots....Boeing reckons knowledge aint power!!!:= )

Bealzebub
15th Apr 2005, 17:21
As I see it,

You should look !

Watch a 757 the next time one touches down. The spoilers will deploy before the nosewheel has compressed, or indeed touched the ground. As haughtney1 has suggested, read it again.

I appreciate you and /or kestrel may think otherwise, but I would be concerned if Boeing feel otherwise because every time I have landed one for the last 20 years the spoilers have activated with the main gear untilt sensors prior to nose wheel touchdown ( other than when the speedbrakes are disarmed of course ). The point about the reversers was simply to add that they are also able to activate the spoilers even when the speedbrake lever is disarmed.

The reference you have provided, refers to the components of the Air /Ground sensing system. You will understand that not all constituents of it are relevant to each and every system.

If you disagree perhaps you could explain this seeming anomaly ?

Jetstream Rider
15th Apr 2005, 20:26
On both the 757 and 767 the spoilers will deploy before noswheel touchdown. When the auto speedbrake is inoperative, it has to be deloyed manually and it says in the MEL to make sure the nose is pitching down before selecting speedbrake. Sometimes in the 767 the spoliers popping out will cause a pitch up moment as you try to land the nosewheel - not usually a problem if you fly it on to the runway, rather than holding it off. Can't remember if the reversers will deploy before nosewheel touchdown (I think they will) - but they will on the 747 - saw it happen yesterday.

Bealzebub
16th Apr 2005, 15:08
__________________________________________________
Not so Bealzebub!

Are you suggesting that you could apply reverse thrust with the nose wheel in the air, not so, below is the AMM32-09-02 reference for air ground sensing:
__________________________________________________


Although I was referring to the spoiler deployment, since you bring up the point, I am afraid you are not correct yet again. The reversers will deploy with the nose wheel in the air. This is because the portion of the Air/Ground sensing system utilised is the main gear untilt. That is (a) in the reference you have provided. ;)

Kakpipe Cosmonaut
17th Apr 2005, 05:40
You will only get half rate auto-braking untill nose wheel oleo is compressed

as737700
17th Apr 2005, 05:54
Like said before, the spoilers will be deployed before the nose wheel touches down.

As I See It
17th Apr 2005, 10:26
As with most things in life I don't believe it until I see it, having done a LPA round trip, and paying particular attention to all things cockpit, I am now in the position to confirm that the spoilers do lift on main gear touch down. I can confirm that this is now As I See It!! :ok:

FLCH
17th Apr 2005, 15:15
I mus agree with Bealzebub I routinely deploy and apply reverser thrrust while the nose wheel is still in the air on the 757's (and 767's), you can balance the aircraft on the main whells, but must lower the nosewheel (gently) before the nose wheel starts to fall itself, typical arrival pitch on the DFDAU is between 2.5 and 3.7 degrees, I used to do it on the 737's too....

pogop
17th Apr 2005, 19:25
Just to add another requirement for automatic spoiler deployment and the deployment of the ground spoilers (4 & 9) - the truck tilt actuators need to be pressurised, as well as both trucks un-tilted and thrust levers at idle. The nose wheel does not need to be on the ground for either automatic spoiler deployment or use of reversers. If you use manual speed brake on landing you may get extra nose up pitch compared to when automatic deployment is used. This is because when deployed automatically there is a time delay of 1.25 seconds before panels 2,3,10, & 11 are raised in order to avoid this nose up pitch.


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