Originally Posted by captjns

Boeing describes three crosswind landing techniques;

“…Three methods of crosswind landings are presented. They are in the touchdown in a crab, the de-crab technique (with removal of crab in the flare), and the side slip technique. Whenever a crab is maintained a crosswind approach, offset the flight deck on the upwind side of the centerline so the main gear touches down in the center of the runway.”

The upwind wing down technique will provide the least amount of torsion type stress to the landing gear as a whole.

While it may not be a specific manufacturers limitation, reducing thrust on the downwind side of the jet may have limiting performance due to go around performance and potential VMC situations from a balked landing at extremely low speeds when flaps are extended beyond the engine inoperative landing position.

Boeing has this to say about touchdown in a crab.

“…the greater amount of crab at touchdown, the larger the lateral deviation from the point of touchdown. For this reason, touchdown in a crab on condition is not recommended when landing on a dry runway in strong crosswinds.”

Originally Posted by jungle

Asymmetric thrust is most commonly used in fairly lightly wingloaded aircraft as a technique to get a little more crosswind capability from an aircraft that has run out of rudder and can't land in a crab. It just adds a little directional control when there isn't enough rudder.
Some heavy jets can land in a crabbed or partially crabbed condition and this may even be preferable in a low friction situation. It also serves to increase the crosswind capability.
I have never seen a jet flight manual recommend asymetric thrust as a landing practice, or a takeoff practice. Would it work? Sure, but they don't want you doing it. Just like they don't want you exceeding crosswind limits or landing on an icy runway with no effective braking. Most of us don't want that recorded on the data recorder or having to explain why we were experimenting with an unauthorized method.

Most anyone can touchdown in any crosswind within reason, the tough part is what happens after touchdown, keeping control of direction after touchdown in a jet is a little different than a light twin and there is less margin in runway width, reverse and braking requirements.

Originally Posted by tomgoodman

Well my reasons were strictly due to personal preference:

I preferred not to be laughed at by the other pilot.
I preferred not to apologize to the passengers.
I preferred not to be slapped by the flight attendants.
I preferred not to report to Atlanta for re-training.

But that's just me -- de gustibus non disputandur.

Originally Posted by Phantom Flyer

This thread has gotten so far off DWS1's original posting but for what it's worth, several large transport category jet aircraft are certified for maximum demonstrated crosswind landings well above 25-30 knts. There is not, nor has there ever been a "safety issue" for passengers. My first landing, during IOE, in a B-777 at ORD was with a sustained crosswind component of 31 knots. Does that make me Superman ? No way ! I'm just flying the aircraft "by the book". It's done all the time. For the record, the B-777 was certified for a maximum demonstrated crosswind of 38 knots simply because the FAA could not find a crosswind greater than that during the certification tests. The B-757 and 767 are similiar in their ability to handle crosswinds, as are a number of other jet aircraft.

Back to the original posting. A transport category turbojet aircraft or any jet aircraft is never landed with one powerplant at a reduced power setting (barring non-normal procedures)to handle a crosswind. One controls roll and yaw issues with aileron and rudder.

I'm sorry Professor...what am I missing ?????

G'Day Mates

Originally Posted by flyingchicken

Therefore, just as upwind reverse would reduce the tire sideload during rollout in contaminated ops and help with staying on the runway, a small amount of downwind thrust during the flare would reduce the amount of wing down required to maintain centerline. Seems quite useful, especially for equipment with limited underwing pod clearance. Good stuff!
Guess you can always learn something new. Filed away for a rainy day (actually that'll be a windy day in this case). Thanks!

Originally Posted by jungle

Uh, no it is quite the opposite. Upwind side thrust is increased to align the aircraft, this doesn't stop drift and requires more down wing to stop it and this makes it especially unsuitable for aircraft with limited pod clearance.

Originally Posted by jungle

Downwind side thrust would increase crab into the wind and complicate directional control and introduce more sideload in the gear at touchdown. That would be like applying right rudder into a crosswind from the right.

Originally Posted by flyingchicken

This mental exercise might help - what does a single engine, power on approach look like in calm wind conditions?

Now add some crosswind from the side with the dead engine. What changes?

Originally Posted by jungle

A series of correct answers.

Once again, touching down is easy, keeping control during rollout is the important part and the runway condition certainly plays a big part in this.

Originally Posted by Phantom Flyer

Maybe it would be helpful to break this discussion up into separate threads; jet aircraft and propeller driven aircraft because there are different techniques for landing each in a strong crosswind.

Originally Posted by flyingchicken

Counter the increased yaw with more rudder. There's more than enough rudder authority - think V1 cut.

I believe theoretically, with sufficient asymmetric thrust, crab angle can be actually zeroed out as the sideslip equals the crosswind component. (Although taken to this extreme, other issues may creep up as previously mention such as asymmetric spoolup for GA, etc...)

Originally Posted by jungle

If there is more than enough rudder authority, why do you feel differential thrust is required?

Originally Posted by jungle

Theory is one thing, but Boeing, Airbus and other jet manufacturers don't subscribe to your theory. This should be considered a clue.