Ask The Pilot

[jb747]

Was that at WLG?

Yes, it was gusting to 65 knots or so...

 

[Mogul]

Surprised it wasn't a go around after the nose came back up.

 

[jb747]

Surprised it wasn't a go around after the nose came back up.

Why?

The landing is interesting. It basically looks pretty stable in what is obviously a strong crosswind. It's all good, right through pushing it straight...at which point the wing suddenly drops. My guess is that the wind decided at that point to either switch to the left, or to suddenly reduce in strength. Or both.

Going around is a nice option, if it actually exists. If a gusty wind suddenly dies on you, and your IAS goes from 130 to 97 kias (!), your go around options are limited...in fact full power in that case simply reduced the magnitude of the heavy landing. In this instance, the nose almost certainly came up because there was still back stick being applied.

The engines would have been taken to idle, and there will be a substantial time before they produce go around power. It isn't as simple as you might imagine.

 

[ChrisGibbs]

Dug up these numbers for A330-2xx/3xx_: Maximum demonstrated Crosswind = 40kts Maximum enhanced Crosswind = 45kts What is the the difference between demonstrated and enhanced? With respect to the A330-3xx / 2xx when landing in conditions like the maximums you sometimes see at airports like Perth is the ability to land restricted by the amount of rudder / aileron input you can use or by the ability of the PIC or all of the above. With the Airbus in Normal Law are the rudder / aileron inputs in the flare limited? Do these limitations get increased under Direct, Alternate (1/2) or Mechanical Law? I seem to recall back in 1999 a QF 747-300 scraping a pod when landing onto RWY 24 in Perth with an excessive crosswind. Thanks in advance

 

[eric2011]

The engines would have been taken to idle, and there will be a substantial time before they produce go around power. It isn't as simple as you might imagine.

When you say substantial time, I know while you are sitting there waiting for it, it will seem like minutes, but in reality, how many seconds are you talking.

Thanks

 

[jb747]

Dug up these numbers for A330-2xx/3xx_:

Maximum demonstrated Crosswind = 40kts
Maximum enhanced Crosswind = 45kts

What is the the difference between demonstrated and enhanced?

I've never heard of an 'enhanced' limit, but knowing Airbus is sounds like something they imagined over a glass of red. Most of their limits are a knot or two greater than the equivalent Boeing, even though the Boeings can be landed with ALL of the drift intact, and the ABs are limited to 5º. The best aircraft I've flown for handling in nasty conditions was the 767.

With respect to the A330-3xx / 2xx when landing in conditions like the maximums you sometimes see at airports like Perth is the ability to land restricted by the amount of rudder / aileron input you can use or by the ability of the PIC or all of the above. With the Airbus in Normal Law are the rudder / aileron inputs in the flare limited? Do these limitations get increased under Direct, Alternate (1/2) or Mechanical Law?

The degraded laws all take limits away. All of the crosswind limits are defined in normal law. In general, you'd want to be much further inside the limits as the laws degrade.

I seem to recall back in 1999 a QF 747-300 scraping a pod when landing onto RWY 24 in Perth with an excessive crosswind.

That was a rather unusual event. The crosswind wasn't excessive as such, but it was switching about a bit. The aircraft had the pod scrape at less than the Boeing defined limits for bank. Ultimately it was decided that a roll control input to fight the gusty wind had resulted in the wing flexing to a point that it caused contact...not something that had really been considered.

 

[jb747]

When you say substantial time, I know while you are sitting there waiting for it, it will seem like minutes, but in reality, how many seconds are you talking.

The engines have a couple of idle settings. Basically flight idle, and ground idle. To come up from ground idle you could be looking at anywhere from 5-10 seconds. Flight idle will probably halve that. Prior to the flare, whilst you still have approach power, it will be almost instantaneous. Add to that the limitation that go arounds MUST not be initiated once reverse thrust has been selected (and for most of us that's within a second or two of touchdown).

Given the way the wing has dropped in the image, you could well imagine that it has been accompanied by a dramatic drop in the IAS. You're already on the ground...no reason not to stay there.

On the other hand, he might be an ex 737 pilot, who's silly enough to drop the upwind wing on a big aircraft....

 

[ChrisGibbs]

A couple of interesting scenarios in YSSY this morning 18th August with the strong Westerlies.... A missed approach onto RWY 25 by QF507 also QF11 A388 OQL SYD-LAX departed off RWY25. Is a A388 limited for fuel when having to use RWY25 for departure? Would an A388 have the legs to get to KLAX or would it need to do a splash and dash into Nadi? See a couple of shots from FR24 below and also the YSSY TAF.

YSSY	17/08/2017 UTC TAF YSSY 172300Z 1800/1906 26030G45KT CAVOK FM180900 26020G30KT CAVOK FM181400 23018KT CAVOK FM182300 20025G35KT 9999 SCT040 RMK FM180000 SEV TURB BLW 5000FT TILL181400 FM181400 MOD TURB BLW 5000FT T 16 17 16 14 Q 1008 1006 1008 1011

 

[jb747]

Is a A388 limited for fuel when having to use RWY25 for departure? Would an A388 have the legs to get to KLAX or would it need to do a splash and dash into Nadi?

With the wind being called as gusting 30 to 45 knots, if you used 30 in the t/o calculations you'd be looking at a performance limited weight only marginally below the max (within a tonne, if you use packs on APU). I'd probably be a bit more conservative, and use 25 knots of headwind, but you're still comfortably above the weight required to get to LA (which is only about 550 tonnes versus max of 569).

This sort of wind would be much more limiting in Australian summer, for a flight to Dubai, where you'd probably need over 560 tonnes, and the temperature would reduce your take off performance.

Anyway, no need for a splash and dash anywhere.

 

[Mogul]

Interesting watching an AA 777 take of from 160L this morning. Not long after a QF 744 was lined for what seemed around 15 mind started roll and then aborted shortly later.

Love watching the landings in these conditions as well.

 

[jpk]

A couple of interesting scenarios in YSSY this morning 18th August with the strong Westerlies.... QF11 A388 OQL SYD-LAX departed off RWY25.

QF7 SYD-DFW also went off runway 25 while I was at the airport, which was the first time I'd personally seen an A380 do that.
At the same time QF63 SYD-JNB sat down at the end of 34L for quite a while, this flight was eventually cancelled due to a tech issue.

 

[ChrisGibbs]

JB747 - Similar to the scenario above casting your mind back were the 744's limited in their ability to use RWY25 for long haul flights. I recall on the old QF107 SYD-LAX flight where the operational RWY was RWY25. According to the Captain we were too heavy to use RWY25 and the cross wind on RWY34L was still within limits so RWY34L it was. We taxied down to the threshold of RWY34L but waited for 15-20 minutes for take off as we were 'orphaned' on an alternative runway and had to wait for a break in the departing / arriving traffic on RWY25.

On a few occasions prior to the introduction of the A388's and during the hot summer months where the temperature rose above 40C we took off from RWY25 but needed to do a splash and dash into Nadi...

Thanks in advance.

 

[jb747]

JB747 - Similar to the scenario above casting your mind back were the 744's limited in their ability to use RWY25 for long haul flights. I recall on the old QF107 SYD-LAX flight where the operational RWY was RWY25. According to the Captain we were too heavy to use RWY25 and the cross wind on RWY34L was still within limits so RWY34L it was. We taxied down to the threshold of RWY34L but waited for 15-20 minutes for take off as we were 'orphaned' on an alternative runway and had to wait for a break in the departing / arriving traffic on RWY25.

On a few occasions prior to the introduction of the A388's and during the hot summer months where the temperature rose above 40C we took off from RWY25 but needed to do a splash and dash into Nadi...

If I recall correctly the 747 crosswind limit is 35 knots. If the crosswind exceeds that, then you can't take off from that runway. But, to be able to use a crossing runway, without a performance loss, then you'd need to gain from the wind, performance at least equal to the loss from a shorter runway. These winds are also normally gusting, so if the wind were a crosswind of 25-45 knots on the long runway, you would have to use the 45 knot figure (worst case) to decide the crosswind situation....but, when you then swing onto a crossing runway for takeoff, the worst case becomes the least headwind...you'd have to use the 25 knot figure. The upshot is that you need a lot of wind to offset the much shorter length of Melbourne or Sydney's crossing runway.

Added to this is the fact that the A380 has better take off performance than the 747 (and 777). Out of LA, we can almost always use 24L at MTOW, whilst the Boeings will need to use the longer 25s for the the departure. Of course temperature comes into play here too. On the 380, I've seen a temperature high enough that we could not use 16/34 in Melbourne at about 20 tonnes under MTOW. In that case no runway is acceptable, and you either plan on refuelling somewhere or wait it out. As the aircraft will almost always already have been refuelled, the choice mostly doesn't exist..you just have to wait.

 

[ChrisGibbs]

As the aircraft will almost always already have been refuelled, the choice mostly doesn't exist..you just have to wait.

Do the company operations team submit a standard order for fuel on your behalf for each trip and you can add to this dependant on the enroute forecast and/or forecast at your destination? Or do you submit an order via the company to the refuellers prior to getting to the airport and then add to this as required? As well as high temperatures does the altitude of the airport become a limiting factor when determining which runways can be used (i.e. OR Tambo - Johannesburg - 5,000ft+ / 1680m)?

 

[jb747]

Do the company operations team submit a standard order for fuel on your behalf for each trip and you can add to this dependant on the enroute forecast and/or forecast at your destination? Or do you submit an order via the company to the refuellers prior to getting to the airport and then add to this as required? As well as high temperatures does the altitude of the airport become a limiting factor when determining which runways can be used (i.e. OR Tambo - Johannesburg - 5,000ft+ / 1680m)?

I'm sure there are many elements within the company (all of them) that would love to do the fuel ordering. But, with that power comes the responsibility for dealing with the outcome that any order might bring. The aircraft are often pre fuelled by the engineers to about 80% of the normal order, but the actual order is placed about an hour prior to departure, after I've clocked on, and had a chance to read the paperwork.

The flight plan normally contains some take off limitation data. Not only will it look at the runway and its elevation, but also temperature and ATIS details. That gives an initial answer for performance limited take off weight...good enough for flight planning. But it will be refined a couple of times once we get to the coughpit.

As you can imagine, there are various factions, all pushing their own agenda. Freight and commercial would like as much weight as possible released to them. Ultimately, the operation belongs to the Captain, and if needed, weight will be taken back. Staff passengers, in particular, get the short end here, as it's common for them all to be denied boarding so that I can carry their weight in fuel. This isn't all sectors, or even all days, but getting to MTOW, is always a juggling act.

 

[Quickstatus]

This isn't all sectors, or even all days, but getting to MTOW, is always a juggling act.

Wouldn't a weighing of passengers with their carry on give a more accurate reading of weight?. Presumably the difference between passenger+carryon estimated is not that far different to actual that its worth the excercise? Though if trying to juggle around MTOW, every 100kg counts?

BTW are the catering carts weighed?

If you need 1 ton to be taken back, how many passengers, carry on, checked do you offload?

 

[jb747]

Wouldn't a weighing of passengers with their carry on give a more accurate reading of weight?. Presumably the difference between passenger+carryon estimated is not that far different to actual that its worth the excercise? Though if trying to juggle around MTOW, every 100kg counts?

BTW are the catering carts weighed?

If you need 1 ton to be taken back, how many passengers, carry on, checked do you offload?

Weighing the passengers, and their hand luggage is probably a step too far. It would take too long, and would be very passenger hostile. The loadings are averaged out, and the various agencies approve them. There's obviously some variation factored into it. The staff passengers will not be offloaded...they'll simply never be onloaded.

In round figures, a tonne is 10 passengers. Load control work it out accurately. If some capacity comes up as the loading is refined, I might tell the local agent that they can have 500 kgs for passengers...I don't really care what permutation they use to fit that. On some flights though, the fuel line will be kept attached, and any reduction in ZFW will simply be replaced by fuel. This is the normal procedure for the 94 ex LA.

 

[Awesom Andy]

It was typhoon signal 10 in HKG today, with the system I believe packing winds of almost 100 knots. Somehow, one flight managed to land in that wind (probably the only one who tried). Has anyone here tried to land in such conditions?

 

[jb747]

It was typhoon signal 10 in HKG today, with the system I believe packing winds of almost 100 knots. Somehow, one flight managed to land in that wind (probably the only one who tried). Has anyone here tried to land in such conditions?

According to the standard gibberish on pprune, the wind at the time of the landing was in the order of 070/45 gusting 60KT. That's pretty much straight down the runway. Looking at the groundspeed readout on FR24 for the approach, they aren't especially slow, so whilst it was probably rough, it doesn't look to be outlandish.

In my experience, weather during the typhoons seems to come through in waves. If you can get the timing right you may find that you land, whilst the aircraft in front, and behind you, go around. During similar weather, I've refused to take off, and I've had one flight that gave two go arounds before a landing (and we were told we were the first to land in 24 hours).

Faced with similar conditions a few years ago, when I was supposed to bring an empty 380 up from Manila, we chose to cancel and wait it out. I was prepared to have a look, but the fleet manager obviously felt that giving me an aircraft and carte blanche to end up anywhere in Asia was tempting fate.

 

[lastrow]

On the question of weights , other than loss of weight due to fuel burn does an aircraft lose any other weight during a long haul flight eg LAX - MEL ?