Ask The Pilot

[jb747]

Do delays of this sort affect ATC and the scheduling of takeoffs since, I presume, the delay is only known at the last minute. Or are there some known timings plus communications with ATC to streamline the process?

At most airports you need to call 'ready' to tell ATC that you are all set to take off. 90% of the time that call can be made as soon as ground tell you to call tower. There are some spots that are problematic, and ATC will be as aware of them as we are. Domestic parking bays in Sydney that are very close to the holding point of 16R would be an example.

LAX and Heathrow don't use the ready call, you are simply processed as soon as you reach the front of the queue. In both places the exercise tends to be lengthy anyway, so normally it isn't an issue. If you are having some issues you are expected to say so, in order to allow them to pull you out of the line.

 

[cambriamarsh]

Probably one for domestic pilots, but all comments welcome.

If you wanted to pushback early ... possibly due to predicted worsening weather at the destination or maybe to avoid impending congestion at the departing runway ... what is involved in making this happen? Do you need an operational reason or might you just decide 'lets try to get away a bit early'?

For instance, is any company 'clearance' required or ATC permission needed at the departing or arriving airport prior to the early call for passengers to board?

All pax are required to be 'at the gate' 30 mins before departure so is there any 'come-back' for the passenger if a HLO passenger rocks up at 15 mins before departure and the doors have already closed? That is, are you required to allow all pax the 'normal' boarding window even in you are trying hard to leave early, or does Captain's decision to close the doors early rule (again, it would only be HLO pax who could be excluded)?

Question arises from my experience a few days ago when a 717 flight MEL to HBA was called 15 mins before it usually is and we pushed back 5 mins early, immediately after the past pax boarded, long after the rest of us were seated and settled; weather was good in HBA. Not complaining mind you ...

I have had flights from BNE to AKL leave up to 15 minutes early when there's been a light load and all on board (I've been last a few times ...)

 

[knasty]

JB at what length does the runway start to affect the 380's MTOW? I note that MEL and LAX's max runway length is ~3700m vs 4000m+ at a number of other airports and up to 4450m at DXB; does 3,700m limit you? I imagine DXB's extra-long runway is useful in very hot conditions?

 

[Boris spatsky]

Probably one for domestic pilots, but all comments welcome.

If you wanted to pushback early ... possibly due to predicted worsening weather at the destination or maybe to avoid impending congestion at the departing runway ... what is involved in making this happen? Do you need an operational reason or might you just decide 'lets try to get away a bit early'?

For instance, is any company 'clearance' required or ATC permission needed at the departing or arriving airport prior to the early call for passengers to board?

All pax are required to be 'at the gate' 30 mins before departure so is there any 'come-back' for the passenger if a HLO passenger rocks up at 15 mins before departure and the doors have already closed? That is, are you required to allow all pax the 'normal' boarding window even in you are trying hard to leave early, or does Captain's decision to close the doors early rule (again, it would only be HLO pax who could be excluded)?

We can push back up to 15 minutes early from scheduled departure time when we are going to a destination that does not need an arrival slot. If the destination has an arrival slot, then the issues is complicated because of the slot time - generally we won't bother pushing back early as the slots are too limiting to get one that early (although sometimes you can, but it takes operations a few minutes to find one if there is in fact one available).

ATC won't let you go more than 5 minutes before your slot time; if you don't need a slot, then we can just advise operations and go early.

If we try to go early, we board earlier than normal in the hope that 1) no one is running late and 2) everyone actually hears the boarding call and promptly starts boarding. We won't leave anyone behind who has a confirmed seat. If we board everyone bar 1 passenger and that passenger gets to the gate 5 minutes before ETD, then we will wait for them. I think offload commences about then anyway. It works 50/50. Friday/Sunday nights it never works as everyone wants to keep drinking in the terminal - so I rarely bother in that instance.

Most of the time we can't go early though because our turnarounds are so tight. Getting away 15 mins early only ever occurs when the aircraft has been sitting around for longer than the usual turnaround time. On a min turnaround, the entire period is needed to clean, re-cater and load and offload passengers, bags and cargo. You will never beat it by more than 5 minutes, even on the best turnaround.

 

[Boris spatsky]

Do delays of this sort affect ATC and the scheduling of takeoffs since, I presume, the delay is only known at the last minute. Or are there some known timings plus communications with ATC to streamline the process?

It can indeed affect you if someone calls ready before you; the larger the aircraft it seems, the longer it takes to get the cabin secure for takeoff. We will frequently get beaten to the ready call by Dash 8 and Saab 340s and they may be put ahead of us for takeoff on a parallel taxiway for an intersection departure, but so be it. We can't go if there are people not secure in the cabin...

 

[RooFlyer]

We can push back up to 15 minutes early from scheduled departure time <snip>

Many thanks again.

 

[lastrow]

Just to change the subject a little I want to know about how you use the APO in flight. Is the APO left running during a flight?
Should the APO be required in an emergency eg main engines not delivering sufficient electric power how long does it take to fire up the APO and is it capable of taking the full or part electric load?

 

[jb747]

JB at what length does the runway start to affect the 380's MTOW? I note that MEL and LAX's max runway length is ~3700m vs 4000m+ at a number of other airports and up to 4450m at DXB; does 3,700m limit you? I imagine DXB's extra-long runway is useful in very hot conditions?

I haven't got access to the performance app at the moment. I'll give you an answer in a couple of days.

 

[jb747]

Just to change the subject a little I want to know about how you use the APO in flight. Is the APO left running during a flight?
Should the APO be required in an emergency eg main engines not delivering sufficient electric power how long does it take to fire up the APO and is it capable of taking the full or part electric load?

The APU is normally shut down immediately after engine start. The limitations on its use will vary dramatically across the aircraft types. As a generalisation, it will be available across most of the flight regime on the twin engined aircraft, though starts won't be guaranteed at high levels. It will be started if you lose a generator (or engine) and can fill in for the loss of a single generator. Running solely on the APU, many items would be load shed. Takes about 30 seconds to start.

If I recall correctly, it can only be used for bleed supply airborne on the 747. Generators can't be used at all, and it can't be started. That has a practical use for some take offs, but it would then be shut down.

380 can be started in flight, with bleed and a single generator (out of two) available to approximately 20,000 ft. Mostly used as a bleed source on performance limited take offs, and for redundancy in some auto lands.

 

[joey1695]

Afternoon pilots.
Quick question stemming from an ATC add-on for FlightSim. I know that it is not 100% representative of real life ops however i noticed something curious and wanted to know your views on the subject. My question is: When given a direct clearance to a waypoint etc etc are you ever given a set heading to fly? Ie 'QF1 cleared to RAZZI, fly heading 123°'. I noticed when following the assigned heading that i would not fly directly to the waypoint, but near it. Could be an oddity in the simulation.
My other question regarding this is, does one instruction take precedence over the other when they arent entirely the same. Ie if the heading assigned with the direct to clearance arent entirely matching, which do you go with?
Sorry if my questions and descriptions are confusing! Appreciate both your time and effort in answering all our questions!
Thanks Joe.

 

[Boris spatsky]

Afternoon pilots.
Quick question stemming from an ATC add-on for FlightSim. I know that it is not 100% representative of real life ops however i noticed something curious and wanted to know your views on the subject. My question is: When given a direct clearance to a waypoint etc etc are you ever given a set heading to fly? Ie 'QF1 cleared to RAZZI, fly heading 123°'. I noticed when following the assigned heading that i would not fly directly to the waypoint, but near it. Could be an oddity in the simulation.
My other question regarding this is, does one instruction take precedence over the other when they arent entirely the same. Ie if the heading assigned with the direct to clearance arent entirely matching, which do you go with?
Sorry if my questions and descriptions are confusing! Appreciate both your time and effort in answering all our questions!
Thanks Joe.

Real ATC would never give you a clearance that was direct to a fix or navaid and a heading too. It's direct to RAZZI in which case we select that in the FMS and select NAV on the sutopilot OR a heading where direct to RAZZI is irrelevant (and not included). So the person that built the ATC addon might need some advice i would think..

 

[joey1695]

Thanks for that Boris. I didnt think one would be given with the other. Just a slight quirk of the add-on. Still does quite a nice job however. Thanks once again!

 

[Flyerqf]

Yesterday Qantas subbed their 744 for a 388 on SYD/HKG/SYD.
My question is how they would crew the return flight given it was unplanned and they (presumably) wouldn't have a 388 crew always in HKG just in case of a late sub.

 

[jb747]

Yesterday Qantas subbed their 744 for a 388 on SYD/HKG/SYD.
My question is how they would crew the return flight given it was unplanned and they (presumably) wouldn't have a 388 crew always in HKG just in case of a late sub.

It was known early enough to pax a crew up the day prior.

 

[jb747]

JB at what length does the runway start to affect the 380's MTOW? I note that MEL and LAX's max runway length is ~3700m vs 4000m+ at a number of other airports and up to 4450m at DXB; does 3,700m limit you? I imagine DXB's extra-long runway is useful in very hot conditions?

The calculation of take off data is quite complex. It takes into account runway items like the length, slope, and elevation, but must also account for any obstacles in the departure plane. Wind, temperature, pressure, runway conditions (dry, wet, etc), anti ice, and bleed configuration all come into it.

Melbourne's 3,700 metres will be insufficient from about 35º...depending upon the wind.

Using a generic 4,000m runway (which has no obstacles, or slope, and is at an elevation of 100')..... Zero wind is assumed, and the pressure is 1013 mb. Dry, no anti ice, and bleeds on. All at MTOW and TOGA.

15º requires 3,000m flap 3
20º requires 3,000m flap 3
25º requires 3,100m flap 3
30º requires 3,100m flap 3
35º requires 3,500m flap 2
40º requires 4,000m flap 1+f
45º requires the weight to be reduced to 548.4 tonnes (i.e. minus 20 tonnes)

 

[moa999]

So quite a big dropoff from about 30deg.

How do you account for variable wind? - eg. Gusty or swirly conditions (do you just assume zero wind or even calculate for the potential of a tailwind)

 

[jb747]

So quite a big dropoff from about 30deg.

The configuration change has a big effect. Basically you'll get airborne earlier with more flap, but your initial climb (and so obstacle clearance) will be worse.

How do you account for variable wind? - eg. Gusty or swirly conditions (do you just assume zero wind or even calculate for the potential of a tailwind)

The application will allow the wind to be put in with direction and strength, so the numbers are calculated for the correct components. If the wind direction is variable, we'll use the direction that gives the least headwind component. If the strength varies we use the lower figure...and sometimes conservatism takes over and we use a bit less than that.

If the component gets anywhere near 90º, then we'll start to use tailwind. We use the worst numbers...none of us are keen on seeing the red lights at the end of the runway any closer than we have to.

 

[mushez]

It was known early enough to pax a crew up the day prior.

By crew you refer to flight crew? As cabin crew are trained to to both types? Or is multi type for cabin crew just an EK thing?

 

[jb747]

By crew you refer to flight crew?

Yes.

As cabin crew are trained to to both types?

Some are, some aren't. I have no idea where they took the cabin crew from, so I can't say.

Or is multi type for cabin crew just an EK thing?

I expect it's quite normal across airlines. But, crew aren't generally trained on all types, but only a subset of them. Most cabin crew only operate on the 380...

 

[mushez]

I expect it's quite normal across airlines. But, crew aren't generally trained on all types, but only a subset of them. Most cabin crew only operate on the 380...

I had originally assumed cabin crew were trained on one type only - however on my last EK flight - EK405 - I helped prop up the bar for all of the flight other than take off and landing, and was talking talking to the purser of nearly 10 years service who was behind it for most of the flight - and after through clarification, assured me all EK cabin crew are trained on two types as a minimum and alternate between then frequently in rosters, and some are on the three types they fly. Is nothing for them to swap frames and the cabin crew know SOP between them. Needless to say I did challenge this from my surprise and was thoroughly assured all were trained on two types as a minimum in EK camp - A380/B777 being the more common subset for most EK staff.