Too easy to makes greasers? Questions on the ground effect

[scottb613 1,188]

The 747 is insanely easy to grease on. I flew the 737 for over 8500 hours and recently left the 320 after 3300 hours. The 737 (300 and 500) were fairly predictable. The 320, I could make a number of smooth landings then bam! The 747 landing pretty mechanically, I listen to the radio altimeter call outs. At 50' start pulling the power off, at 30' start flaring, but not a whole lot, at 10' feet, hold the site picture, which requires a tad bit of back pressure. What I noticed in the sim was you knew you touched down when you heard the spear brake moving back. It's has a loudish servo. I've done 8 landing so far in real life. It was just like the sim. 7 greasers and one so-so. The so-so was my fault. I landed flaps 30 instead of the normal 25, it was windy and the runway was SFO 19L. All a bit non standard. I fixated on the aiming spot and didn't change my focus down the runway in the flare.

 

What I'm trying to say is this simulation is pretty realistic. I think real life is a bit easier to grease it on.

Well at least your "so-so" at KFSO wasn't  in a T7 - LOL - as per Asiana with (4) pilots in the cockpit...

:wink:

 

Regards,

Scott

[cmbaviator 5]

Anyway its rare to see hard landing nowadays unles you have maybe like less than 50 hrs on type

[vololiberista 205]

Anyway its rare to see hard landing nowadays unles you have maybe like less than 50 hrs on type

You've never flown BA then! They only ever do "positive" landings. Greasers are frowned upon nowadays.

[Captain Kevin 586]

Well at least your "so-so" at KFSO wasn't  in a T7 - LOL - as per Asiana with (4) pilots in the cockpit...

:wink:

Three. The fourth was in a business class seat and not actually in the flight deck.

[G550flyer 1,013]

You've never flown BA then! They only ever do "positive" landings. Greasers are frowned upon nowadays.

Actually, flight manual procedural landings are a little firm. Once you get a feel for the type, your learn little techniques like slower power pull or perfect your flare timing. A flare is a 2 to 3 degree pitch change. You aim for 3ish on the change with perfect timing. The good landings are when you cross the threshold, on speed, on glide path and touch down at your proper aim point with a greaser. I prefer the perfect timing on the upper end of the pitch change. Puts you down right where you aimed. Slower power pull or changing too much pitch gets you a floater running the risk of dropping it in or tail striking depending the plane. I operate into some short runways at times and you really have to be on speed, height and aim point. I keep my landings consistent so it doesn't matter if I'm on a long or short runway. Guys who get nervous on short runways are usually the ones who are usually fast, high and excessively target greasers.

[cmbaviator 5]

okay guys, i would like some B747 pilots to rate my landing and to give me advice on how to improve my flaring

 

i've done some base trainning with flaps 25 / 30 and 25 with crosswind.

 

For now i only have the flaps 25 :

 

For me i'm floating too much, i'd like some advice on how to obtain the same RoD but with less floating

 

[Chock 17,769]

Landing looks good, but if you want to get it to stop flying sooner, try getting the throttle off much sooner. At Vref you are well above stall speed.

 

Vref, is 1.3 times the stalling speed of the aircraft at its landing weight. As you know, it's the speed which you're meant to be at when crossing the runway threshhold at 50 feet (this is a safety margin so it can take into account gusting, wind gradients, go arounds when minimums are missed etc). But with that in mind, if you keep that speed on too long, when you flare, sure you'll be slowing down, but the increase in AoA from the flare increases the lift (and drag too of course, but the effect of it doesn't happen instantly). Since you're already at almost a third more speed than the point where the aircraft will theoretically no longer be able to fly, when that lift increases in the flare, it will make you float (which you don't want, you only want to arrest the descent rate). All this is especially worth noting when you also consider that you're going into ground effect as you near touchdown, and in ground effect airliners can actually keep flying at well below what would normally be considered the speed where they'd drop out of the sky. That's what is making you float down the runway. Some jet airliners won't actually completely give up flying when in ground effect until they're well below 100 knots, even at fairly high weights (the 737 in particular, is notorious for that). That's why they deploy auto-spoilers.

 

So in other words, you need to be a bit 'ahead of the aircraft' in regard to stopping it flying, by commencing getting that speed off sooner. Don't worry, in a sim you have the luxury of being able to experiment, and you'll find that you can be fairly positive in backing the throttle off on a big aeroplane well early and it will keep going - you only have to try losing speed on a descent to know how slick an airliner can be, even with the flaps out - yes the Jumbo is big and heavy, but even something like a 747 will not lose speed that quickly, even if you chopped the throttle completely, because for one thing it is 'going downhill' at 3.5 degrees, and you know from instances such as 'the Miracle on the Hudson' and 'the Gimli glider' that even a big &@($* airliner has a glide ratio of about 17:1 (as opposed to a Cessna 172, which is about 9:1, and I bet you've dead-sticked a Cessna in your sim loads of times no problem), for another, even at landing weights, the 747-400 weighs a lot, so it cannot suddenly slow down in the space of a few hundred yards, it simply has too much inertia.

[downscc 1,327]

What Alan said.

 

Speed is the key to landing, you approach at Vref+5 then cross the threashold at Vref and over the touchdown zone you want Vref-5.

[scottsware 69]

All those landing look like typical real word landings. No one nails the touch down spot every time. I think the third landing was the best. You did float a bit on the first two ( I think I have the sequence right). Even the ones you floated on looked just like what I see in real life. Even your control movements seemed normal. It's easy to start moving the yoke around too much. The best you can do is noticed you are "stirring" the stick/yoke and force yourself to stop it.

 

I rate what I saw in your video as extremely realistic.

[Copper. 78]

All those landing look like typical real word landings. No one nails the touch down spot every time. I think the third landing was the best. You did float a bit on the first two ( I think I have the sequence right). Even the ones you floated on looked just like what I see in real life. Even your control movements seemed normal. It's easy to start moving the yoke around too much. The best you can do is noticed you are "stirring" the stick/yoke and force yourself to stop it.

 

I rate what I saw in your video as extremely realistic.

+1.

 

Very nice, very controlled. As he says, you're not going to nail the same spot each and every time, nor the touchdown speed, but good and proper technique will ensure that happens most of the time, but not all of the time, which is acceptable... you're not a robot. The overarching principle is to use the right technique to achieve the right speed and attitude to get the plane on the touchdown zone. You do that perfectly in your video.

 

You are doing very well. Now, to challenge yourself even more you can introduce wind to just below the limits (cross, head, tail), and from there, some turbulence/shear (not too much, just a little), and from there, one or two engines inoperative.

[FDEdev 955]

@Chock,

 

If we are talking strictly about planes the size of a 737 and bigger there are a few items that need amendment

1. Vref is definitely not the speed you want to have over the threshold at, it's at least Vref+5.

2. You never ever reduce thrust at idle too early e.g. at the threshold in a heavy. In fact e.g. the 767 training manual recommends that the thrustlevers should reach idle when the maingear touches down.

If a high sink rate develops during the final stages of the flare in a heavy and thrust is already at idle you are in a really bad situation as pulling the nose up without thrust will make matters even worse.

3. L/D ratio of an Jet airliner might be approx 17 but that's at high speed and in clean configuration!  With full flaps and gear down drag is very high with planes like the 767 or the 747. At flap limiting speed and idle ROD can easily reach 2000-2500ft/min.

4. A nomal glideslope has 3deg.  3.5 is rather steep, requires less thrust and keeping the thrust into the flare is important in this case because of your low energy state.

5. Just to make sure, although the 737 has autospoilers, they don't deploy in the air while in ground effect and not even a 737 at minimum weight will fly below 100kts in ground effect.  

 

The aim is to cross the threshold at Vref+5 (Minimum!) and (depending on the actual speed) slowly start to reduce thrust between 10-30ft.

The target isn't a supersmooth touchdown. Just break the ROD and let the plane fly onto the runway.

What does cause a very noticable pitch down moment which needs to be actively counteracted on planes like the 767 is the thrust reduction. 

[Chock 17,769]

Yup, all that is true, but I was making suggestions for if, as in that particular post, they were wanting to get it down sooner. We have the luxury of being at the controls of a simulated aeroplane, and so we don't have to follow real procedures if we don't want to; if it pleases someone to want to nail it onto the piano keys every time, the suggestions I made are what will make that happen. Personally, I'd be happy with the landings as they were in the video, they saw the aircraft down in a stable and safe fashion with plenty of room left to stop, and I long since stopped trying to grease it on in real life when flying an aeroplane, because as I learned to my cost (in terms of pride) if you stuff it up, you will land hard. But even if someone wants to turn onto final in the last 20 seconds and then come down in a Khe Sanh approach in their sim, then there is nothing stopping them doing that if that's what floats their boat. :smile:

[FDEdev 955]

Ah ok, I see, btw I love to do greasers IRL as I don't have to pay for the (8) tires

[Chock 17,769]

Ah ok, I see, btw I love to do greasers IRL as I don't have to pay for the (8) tires

 

lol. Unfortunately I do, even in the simulator, thanks to Air Hauler 2

[cowpatz 243]

Without doubt the 747 is the best aircraft ever built and is a real pilots machine. It is very manoeuvrable and forgiving given it's size. I have spent many a pleasant hour flying the old girl both the -200 and -400 derivatives. It has a reputation for being an easy aircraft to land.
A good approach generally leads to a good landing (as always there are exceptions) so get this part right to help make your landings easier.

In the early days most jet aircraft were configured in the landing configuration by the outer marker and flew the whole final approach at VREF+ an additive. As fuel became more expensive airlines adopted low drag approach techniques which consisted of delaying selection of both the landing gear down and the landing flap position. Typically the landing gear is lowered anywhere from 2000 to 1000 ft and the engines spooled up in the landing configuration by 1000 to 500 ft. However an undesirable consequence of this technique (and step down non ILS approaches) is the increased risk of either high descent rates developing and or high landing speeds, usually with engines unspooled, or at very low thrust settings. In an effort to reduce the number of landing incidents (runway under and overruns) most airlines have adopted a stabilised approach policy. This is whereby the aircraft must be configured in the landing configuration, on speed, spooled up and with a normal rate of descent by either 1000 or 500ft above aerodrome level or else a mandatory go-around is carried out. This point in space is referred to as "the stable gate" and typical criteria for a wide-body would be:

• established on correct glidepath
• Airspeed +10 or -5kts of target speed (TTS)
• Sink rate <1000fpm - or if going to be higher then brief for it beforehand ie. non normal landing config.
• thrust appropriate (not idle)

To help achieve this an airline may implement configuration requirements such as (wide body):

• Gear selected down by 2000 ft AAL (above aerodrome level)
• Landing config established by 1000ft AAL
• Stable by 1000ft AAL or GA

These would be good to aim for in your own flying. This now places us on slope, on speed and hopefully in trim. If you are then you shouldn't really need to adjust the trim. All we have to do now is enjoy the ride.

Your final approach speed (TTS - Threshold target speed) can be determined by adding 1/2 of the steady headwind component plus all of the gust factor up to a maximum of 20 kts and a minimum of 5 kts. So for example if we were landing on Rwy 36 with a wind of 060/20 G35 the headwind component would be 10 kts and the gust factor 15 knots.
In this case our additive would be 10/2 + 15 = 20. If on an autoland just use 5 kts as the Autothrottles remain engaged.

From the corner of your eye monitor the thrust setting and if you see it start to increase signifcantly from the norm then check forward and the opposite if thrust reduces by easing back. This changing thrust setting could be due to something like "chasing" the GS or encountering a gust or shear and is to preempt the resultant pitch change that will occur with thrust changes. This is due to the pitching moment produced by big underslung engines. If you where already on speed then resist the temptation to trim as you will hopefully soon be through the area of shear or be back on slope. Remember the pitch, power speed/trim relationship.

Fly the electronic glideslope in preference to the VASI or PAPI when on an ILS. In large aircraft they will guide you to different aiming points. Fly the visual slope indicator if on a non ILS approach. This is of course in the RW and may have limitations when applied in flight sim as it depends on how accurately the scenery developer placed the GS and VS aids. This difference in aiming points is due to the difference in height between the GS antenna height (ILS) and the pilots eye height (VASIS or PAPI) and minimum landing gear clearances crossing the threshold. If you look at any runway that is utilised by large aircraft you will notice that the visual slope aid is positioned further down the runway than the GS antenna. Visual slope aids are always positioned abeam the aimpoints (the big blocks) marked on the runway.

If on an ILS aim to land between the second and third markings (300m to 450m) and go-around at the last set or 1/3 of the way into the runway whichever is less.
If following a VASIS or PAPI, as you would following a Non - ILS approach, then then follow it and aim for the large blocks. Of course this all assumes that the markings have been done correctly by the developer.

 

As I teach it to new crew learning large aircraft landing techniques:

• At 100ft "wake up" and 50ft "look up". In fact for the 747 as the nose crosses the threshold and it passes behind will do. (Disconnect the auttothrottle at the 50ft call unless on an autoland)
  At that point look to the far end of the runway. This will assist with the flare.
• At the 30 ft call ease back on the yoke to arrest the rate of descent (only 2 to 3 degrees pitch up - but don't look at the ADI)
  Hold the attitude making only small corrections if required to maintain descent rate and retard the thrust levers to idle (pitch up first then retard - especially when heavy). Thrust levers should be at idle by touchdown.
• Hold sufficient back pressure to maintain the attitude. Do NOT trim in the flare.
  Let it settle on. Flare times can be from 4 to 8 seconds in duration.
• The attitude on touchdown should be between 4 and 5 degrees. (you could perhaps look at this during a playback to check).
• After touchdown don't just release the yoke but initially hold the attitude, select reverse thrust and then lower the nose and fly the nose wheel onto the runway.

I find that landing a light 747 I would start the flare between 30 and 20 ft. After a while the rate of change of the radio altitude call outs will give you a clue as to runway closure rate.

2 things generally will lead to a poor touchdown.

• Unstable approach
• Not looking at the far end of the runway from 50 ft and during the flare.

Happy landings guys.