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AviatorInsight

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Ok thanks. Next Q:

Jindabyne glider friend swears that NZ1197 LAX-MEL routing over CBR-YJIN is unusual (because he heard it in Jindabyne). He reckon the mountain wave carried the jet noise. At the time it was FL400

Anything unusual about the routing?. Seems normal to me
And would Snowy Mountains Mountain wave transmit jet noise from FL400 to ground?
Yes, given it’s quieter in the surroundings, and elevation above sea level is above 5000ft (making the real altitude above ground in the low 300s), I think it’s possible to hear it.

As for the routing, seems normal to me.

Question about Mountain Wave
I often go to Jindabyne
General aviation flying around YJIN often have to contend with Mountain Wave

Do commercial aircraft at FL400 experience mountain wave when over the the snowy mountain - say on a LAX-MEL QF94?
I have experienced mountain waves many times flying to the south coast into Moruya and Merimbula turbulence was very rough at low level. I even experienced it just a few months back with an extremely strong low level jet that brought winds from FL200 - FL330 upwards of 150kts. We were flying from SYD - BNE and could tell it was mountain wave activity along the spine of the great diving range.
 
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jb747

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Jindabyne glider friend swears that NZ1197 LAX-MEL routing over CBR-YJIN is unusual (because he heard it in Jindabyne). He reckon the mountain wave carried the jet noise. At the time it was FL400.
I haven‘t been keeping up with who‘s flying where, but I’d have thought that ANZ doing direct LA-MEL was unusual in itself. When I was flying it though, there was dramatically more traffic around than there is at the moment, so we normally joined the airways near Sydney, though a couple of other routes did come in further south. At the moment, I doubt that that ATC have any issues fitting aircraft in, so direct routes are probably more likely than not.

I don’t think the mountain wave would have anything to do with your friend hearing the aircraft or not. The Melbourne Sydney route is about 12 miles east of my house, and we can hear the aircraft if you’re outside, irrespective of their height.
Anything unusual about the routing?. Seems normal to me
And would Snowy Mountains Mountain wave transmit jet noise from FL400 to ground?
 
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jb747

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Are there any visual clues to Mountain wave activity.
What does Mountain wave do to an aircraft ?
Flying a flight level means that you are flying at a constant pressure level. In wave conditions, the real altitude of that pressure level goes up and down, so you get the effect of of flying up and down a series of slopes. It can be quite an issue at higher levels, if you are near your limit altitude, as you may have insufficient power to get up the hill. It isn’t necessarily turbulent.
 

AviatorInsight

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Are there any visual clues to Mountain wave activity.
What does Mountain wave do to an aircraft ?
You may sometimes get lenticular clouds at the peak of the mountain where it‘s shaped like a lens. In the aircraft you get this oscillation and the speed slows down and then speeds up as you go up and down the hills. That’s what we were experiencing as we were climbing out on that flight. But notably it was smooth up high.
 

kookaburra75

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interestingly the recent QF94 (24Jul) did just that. It turned right at Mallacoota.



Maybe for light aircraft?
I'm not sure about light aircraft, when flying in wave conditions in gliders you avoided the Rotor Clouds at all cost. It would only end in disaster ( Mountain wave turbulence or UBC ATSC 113 - Rotor clouds) Prior to getting towed up into position to start the wave flying you planned everything to the nth degree, as things could go very wrong, very quickly, including main routes, escape routes etc.

The Lenticular Clouds that @AviatorInsight mentioned in his post are indicators of where you want to be, downwind to get into the climbing part of the wave. A flight would normally start further downwind of the main waves, and you would climb in the nearest wave, then dash forward to the next wave, climb and repeat.
 
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Saab34

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JB how sensitive is the Airbus sidestick? Small inputs? Anything surprise you when you first started using it compared to the Boeing? I’d imagine it’s a fairly big change.

Is the inputs much the same across all Airbus series?
 

jb747

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JB how sensitive is the Airbus sidestick? Small inputs? Anything surprise you when you first started using it compared to the Boeing? I’d imagine it’s a fairly big change.
The sidestick itself is easy to come to terms with. The motion is quite natural, and I far prefer it to a control yoke. Mind you, I also prefer actual joysticks to a yoke too. The lack of feedback can be an issue, not so much for the pilot flying, but for the other pilot to keep track of what inputs are happening.

What you do have to come to terms with though, are the control laws. In normal law, you use the sidestick to put the aircraft into an attitude that you want, and then it will keep itself there, with no further input. In a non FBW aircraft, even when properly in trim, small inputs are pretty much constantly needed. So, the tendency in coming from the 747 is to over-control. Basically less is best.

If the controls degrade, and you end up in direct law, they revert to behaving more or less like non FBW aircraft, so they change from being a rate control (normal) to simply controlling the position of various control surfaces (direct).

Landing is interesting in that normal law is not appropriate for flaring an aircraft, so there is a 'landing' mode. In that, at about 100' the aircraft reverts to direct law in pitch, but remains in normal law in roll. That works well for pitch control, but in a crosswind, I found that it was a bit 'granular' in roll, with it being difficult to select and hold very small angles of bank (2º or so).
Is the inputs much the same across all Airbus series?
As far as I know, as I've never flown other than the 380. Many of the FOs, and some of the SOs, had flown the 330 and 320, and I don't think they ever commented on control response. They did talk about the autothrust and its interaction with pitch control. Basically it worked well in the 380, but a lot less so in the others. The upshot of that is that on gusty days, you'd leave it engaged in the 380 for landings, but on the others they'd often disconnect it.
 

LPS144

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The sidestick itself is easy to come to terms with. The motion is quite natural, and I far prefer it to a control yoke. Mind you, I also prefer actual joysticks to a yoke too. The lack of feedback can be an issue, not so much for the pilot flying, but for the other pilot to keep track of what inputs are happening.

What you do have to come to terms with though, are the control laws. In normal law, you use the sidestick to put the aircraft into an attitude that you want, and then it will keep itself there, with no further input. In a non FBW aircraft, even when properly in trim, small inputs are pretty much constantly needed. So, the tendency in coming from the 747 is to over-control. Basically less is best.

If the controls degrade, and you end up in direct law, they revert to behaving more or less like non FBW aircraft, so they change from being a rate control (normal) to simply controlling the position of various control surfaces (direct).

Landing is interesting in that normal law is not appropriate for flaring an aircraft, so there is a 'landing' mode. In that, at about 100' the aircraft reverts to direct law in pitch, but remains in normal law in roll. That works well for pitch control, but in a crosswind, I found that it was a bit 'granular' in roll, with it being difficult to select and hold very small angles of bank (2º or so).

As far as I know, as I've never flown other than the 380. Many of the FOs, and some of the SOs, had flown the 330 and 320, and I don't think they ever commented on control response. They did talk about the autothrust and its interaction with pitch control. Basically it worked well in the 380, but a lot less so in the others. The upshot of that is that on gusty days, you'd leave it engaged in the 380 for landings, but on the others they'd often disconnect it.
How much of a change is it for a FO going to a Captain with the sidestick being utilised by the right hand then across to the left? I imagine it would take some time given muscle memory is probably use to one side then gets flicked to the other?
 

OZDUCK

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This video is doing the rounds at the moment. Apparently an Indonesian registered aircraft landing at Bhutan Airport - which is said to be a very treacherous approach. But this effort does seem to be a bit extreme. Any, printable, comments?

 

jb747

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How much of a change is it for a FO going to a Captain with the sidestick being utilised by the right hand then across to the left? I imagine it would take some time given muscle memory is probably use to one side then gets flicked to the other?
It's fairly common through a career to need to change hands. I was right handed in everything military, but then in the airline, as an SO, I had to be ambidextrous. FO right handed again, and then left with command. Basically you do have to learn it, but it disappears amongst all of the other things that are happening in command training, so it isn't a huge deal in itself.

Whilst a control yoke does have two hand grips, they're generally flown single handed, using the same hand as you would with a joystick. The thrust levers are almost always in the centre, so the inboard hand always needs to be there. People who use both hands invariably overcontrol.
 

jb747

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This video is doing the rounds at the moment. Apparently an Indonesian registered aircraft landing at Bhutan Airport - which is said to be a very treacherous approach. But this effort does seem to be a bit extreme. Any, printable, comments?
Well, he hits the runway, so it's obviously not the worst landing ever. But it sure isn't something to be proud of.
 

mjt57

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This video is doing the rounds at the moment. Apparently an Indonesian registered aircraft landing at Bhutan Airport -
Looks my landings when I had gift certificates to the sims (B737-800 and A320). At least they got it down. Didn't look much worse, thump-wise, than the planting that we experienced at HNL in a Deathstar NightmareLiner a few years back.
 

AviatorInsight

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This video is doing the rounds at the moment. Apparently an Indonesian registered aircraft landing at Bhutan Airport - which is said to be a very treacherous approach. But this effort does seem to be a bit extreme. Any, printable, comments?

Yep the centreline is just a suggestion it seems. The SOPs are incredible given the hard terrain/bank angle warnings and just a response of “checked”. They were obviously under the premise of any landing you can walk away from is a good one.
 

jb747

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Gentlemen. Thoughts? Looks uncomfortable.
Interesting, though I’ll leave the stone throwing to those who have never planted one. The Captain’s response, slamming the thrust levers forward, immediately after the FO had closed them, has been prompted by something. There doesn’t seem to have been any flare. You also hear ‘priority left’, which indicates that he’s taken over and pressed the override switch on the joystick.

On a gusty day, closing the thrust off before the flare is established can be a gotcha. The backside certainly falls out of it.
 

Saab34

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What’s the result of not pushing the levers forward in a situation like this? Bounce and tail strike?
 

jb747

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What’s the result of not pushing the levers forward in a situation like this? Bounce and tail strike?
Tail strike only happens if you over rotate the aircraft. A small bounce isn't too dramatic; as long as you hold the attitude, it will come down again, and as it will have less energy, will probably stay there. A high bounce should be taken around, but again, hold the attitude until the power is up, and you are well clear of the ground.

In an Airbus, closing the thrust levers disengages the autothrust, which you normally want out before the flare is complete. Otherwise, is will add power through the flare to maintain your speed, and in theory you might end up flying along, nice and level at a couple of feet. That's the reason for the 'retard' call that is so well known. But, it's a dynamic environment, and there are plenty of occasions when holding a bit of power through the flare is necessary. As a side note, the retard call was a reminder that you should already have pulled the levers back, and it didn't activate at all in most landings.

Looking at a different aircraft, the 767.... QF had three different types of these, the P&W 200s, the RR 300s and the GE 300s. All three had different flare techniques. The power was reduced in the GEs much earlier than in the RRs. It was generally best to complete the flare in the RRs before you reduced the power at all, which was a technique that would give you a monstrous float if you did in in a GE. Conversely, using the GE technique on an RR was a guaranteed way of planting it.
 

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