Do we “bump down” these days? I was taught to land……
 

This was taken from another thread, quoting another user. But I was curious, How difficult is it to land a 737? or any 'large' commercial aircraft?

The landings always seem rough, but am told that particularly with the 737, you gotta put it on the runway quickly, without the need for a smooth touchdown?

Not a beat up, genuinly interested, are commercial pilots taught a smooth landing is important or does the plane need to be dropped onto the runway to keep it there?

Dog

i reckon the classic is easier to get a decent landing out of compared to the ng

I'm not too sure how they did it in the old days but there are the company stabilised approach requirements which can be 'policed' with the help of QAR's. Some one else may care to comment if they have noticed any changes in handling, speeds being flown etc. and has this had any impact on the apparent deterioration. For example the Dash seems to land so much nicer at Ref+10 and harder 'on speed', or maybe it's just me.

I can't speak for the 737 but I appreciate and comment if the bloke next to me flew the speeds, puts it firmly right on the 1000' marks and centerline of course:p . Anything else like 'mucking around' and floating looking for a greaser doesn't do it for me:rolleyes: .

Having said this, yes I'm guilty of bumping it on every now and then;) but when the greaser happens it feels fantastic knowing that I put it exactly where I wanted:) .

I close my eyes from 100' above...after all, "Any one you walk away from, is a good one!"

These sorts of professional secrets are VERBOTEN, dogi...so don't believe ANYTHING you read!! :E

In my book, you get far more points for touching down on the nominated spot (eg 1000ft markers) than you do for a "greezer" somewhere else. If you can get both together - good one!

Most accidents occur on approach and landing and many the result of not flying a stable approach according to well established criteria (FSF etc).

Any move away from flying the right speeds etc or trying for a greezer whilst floating well past the 1500ft marks is only asking for trouble. And if the Rwy is wet, then a firmer touchdown is the go.

I seem to find many pilots these days that don't have the basic skills or self discipline to put it on the spot 100% of the time. Something to do with training I believe?

Why?

It avoids aquaplaning

Oh really!!
And how does it do that?
Aquaplaning is a function of the square root of the tyre pressure, and will occur at an almost set speed on each aircraft type, regardless of how firm or otherwise the touchdown was, if there is sufficient standing water.....unless you figure you can make your "firm touchdown" at that speed.

What the passengers notice ?
 

If the runway is very long, much longer than "landing distance required", then I cannot see anything wrong in floating longer to make it a greaser, especially in an aircaft type difficult to "grease on".

Remember this very important fact :

The passengers (who keep the airline alive and pay our salary) can all feel the difference between a greaser and a thump,

but

the passengers got no absolute idea about touchdown zone markings etc,

Remember, some passengers are still very scared of flying and by making it a smooth flight followed by a smooth landing might encourage them to fly again one day or feel better about it.

Ill go with John Citizen on that one,

If landing distance avaliable is not an issue Ill always make an effort to grease it on with pax. Admittedly in my applications however it concerns light piston a/c only.

"Oh really!!
And how does it do that?
Aquaplaning is a function of the square root of the tyre pressure"

True when the entire weight of the aircraft is on the tyres. If a landing is "Greased" there is a period when the wheels are in contact with the runway, but the wings are still producing sufficient lift to support part of the weight. This has the same effect as a lower tyre pressure i.e. lower and wider range of speeds for aquaplaning.

Touching down firmly (a good idea at all times) puts all the load on the wheels and deploys the speed brakes in the shortest time, raising the the speed and shortening the range of possible aquaplaning.

By the way Kap,

How come you'll reply on this thread, but not on the one where you couldn't work out which decade an incident report was from?

I'm not sure if it'll do much about aquaplaning - not that I'm saying it won't I just don't really know - but placing the aircraft firmly down in the TDZ will:

*minimise risk of a float and associated increase in landing distance
*correspondingly minimise the time taken to speedbrake deployment and ability to actuate reverse thrust
*by reducing time to full speedbrake deployment, maximise the weight on the wheels sooner and therefore increase braking effectiveness.

My two bob's worth.

So if you want to make it a "greaser" then you have to "float down the runway" ?

If that is the argument, then why not aim for the 500' markers, float for 500' and "grease it on" at the 1000' markers ? surely this meets ALL requirements ?

Personally, my approach is to touch down on the 1000' markers AND try to grease it on. works most of the time, provided one remembers that Vref is the speed at which one should cross the threshold at 50' AGL, and not a touchdown speed!

You should be able to land smoothly AND touch down at the correct spot AND in a limiting crosswind, if you were trained correctly, and have some manipulative ability. IMHO the only pilots who advocate "firm" touchdowns are those who can't land properly or have no manipulative ability!
The training should have been done at abinitio, not on transition to heavy jets, as some think appropriate.:E

In my opinion it is a foolish driver who puts 'greasing it on' ahead of precision. Sure you should aim for the spot AND try to minimise the thud - in that order. Wizofoz is quite correct, a positive touchdown minimises tendancy to aquaplane on a wet runway, further to that (I was told by an old pilot many years ago) drawing out the touchdown or greasing it on increases tyre ware (delamination) - not sure to what extent this is true these days (better tyres) but it makes sense, the sooner the wheels are doing the same speed as the aircraft, the less rubber you leave on the tarmac - anyone else care to comment on the validity of this. Points about spoiler deployment etc are also valid.

By the way, I'm not talking spine compressing 'arrivals', just a gentle, but positive touchdown - ask Boeing or Airbus how their aircraft were designed to be landed!:ok:

FFS...a 737 is as difficult to land as a cherokee 6.

Whats the mystery?

Sure I'm not a pilot, but we were advised in good ol' ATC school - (I did the course at the now defunct Henty House, Melbourne) that weight of the vehicle had no bearing on aquaplane speed.

Aquaplane speed was a function of tyre pressure and speed, and that weight (or mass) of the vehicle had no effect. Hence, the advice to thump it down, because there was therefore more mass exerting force on the tyres would be incorrect.

We were also advised that to determine your aquaplane speed roughly (in mph), you take the square of your tyre pressure (in psi) and multply by 9. Hence if your tyre pressure is 25psi, your rough aquaplane speed is 45mph. Hence most cars will aquaplane at 80kph. I've managed to have it occur to me while driving through a large puddle at 90kph.

The reason we were advised about this using the old imperial measurements was because the film depicting the experimentation on aquaplaning was done by NASA. It showed a B1 thumping it down, then slowly drifting off the runway.

Tread pattern will make little difference, but grooves in the runway allow the surface water on the runway to drain quickly and help reduce the incidence of aquaplaning.

Correct me if I'm wrong, but I'm sure the info I received way back then is still correct.

Pierre,

you information is correct, but consider this...

the boeing documentation says that firm arrivals in the correct position are preferred over landing long and holding off for a greaser - tail strike being one consideration.

anyone who advocates landing long in order to get a greaser is on the wrong track in my opinion - but then I also disagree with Dash-8's landing long just because they can - it is most unprofessional in my opinion....

DHD, does this mean you were not of the brigade who used to land (just) on 03 at Perth with a touchdown about abeam Delta? ;)

I do notice the difference in the landings between a 737 and the 146. I've been doing a fair amount of commuting to Kal and Telfer over the last few months and the 737 landings always seem to be pretty positive, whereas the 146 just seems to trundle down onto the runway. Why is this?

But then again, sitting in the arse end of a 146 is a damn sight more uncomfortable (bouncy) than the 737 when cruising.:E