Ask The Pilot

[jb747]

jb, how does descent from cruise work? You have mentioned ATC in the US can leave you with "High energy offsets". Is this all part of the same thing please?

Most of the time ATC will give you a descent from cruise either when you want, or earlier. Sometimes it will come after the desired point, in which case either increasing the speed, or using the speed brake will fix the profile fairly quickly.

Problems arise when ATC want either a higher speed at low altitudes, or when they don't clear you to descend as required inside 20 miles. The problem progressively gets worse the closer you get to the runway. A thousand feet of offset at 100 miles is trivia (3% or so), but that same thousand at 10 miles is 33%. Couple that with higher than normal speeds, and you'll eventually end up with an energy state that can't be reasonably fixed. Even requests to hold 160 knots until 4 miles (a very common one) cannot be complied with as it would often mean you'd exceed the 'stable approach' tolerances once you go below 1,000 feet.

This issue is most common in the USA, where they seem to have little concept of the problems involved in getting a very large aircraft down, but are used to compliance by locals in much smaller jets. It is easily the most common cause of company go arounds in Los Angeles. Whilst not the cause of the SFO 777 accident, it would seem to have been one of the links in the chain.

 

[sdhog2002]

Didn't know whether I should ask this here, but saw your response to the Bacchus Marsh question so thought I might, if you don't mind. We live near St Kilda in Melbourne and I have seen some planes cruising (high up) in what seems to be a South to North flight path just west of Melbourne. Where would those 'planes be flying from (and to?) I would have thought any flights from Tassie would be more to the East of Melbourne (and where would Tassie flights be going pretty much directly North?)
Sid

 

[jb747]

Didn't know whether I should ask this here, but saw your response to the Bacchus Marsh question so thought I might, if you don't mind. We live near St Kilda in Melbourne and I have seen some planes cruising (high up) in what seems to be a South to North flight path just west of Melbourne. Where would those 'planes be flying from (and to?) I would have thought any flights from Tassie would be more to the East of Melbourne (and where would Tassie flights be going pretty much directly North?)
Sid

As suggested, the FlightRadar app will identify any overflying aircraft. But, the aircraft you are looking at are most likely not from anywhere near Tasmania. The QF64 (from South Africa) often overflies Melbourne on a very northerly track. I expect flights from Christchurch could also regularly appear. Even flights from Dubai to Sydney could come very close to being on the track you describe.

 

[petercr]

JB, what about planes heading out of Avalon heading north after taking to the south?

 

[jb747]

JB, what about planes heading out of Avalon heading north after taking to the south?

Yes, they could well fly over Hopetoun Park, though certainly not St Kilda, and hopefully not any 380s.

 

[markis10]

Yes, they could well fly over Hopetoun Park, though certainly not St Kilda, and hopefully not any 380s.

Although most AVV departures will set course over MEL, well clear of the city.

 

[southernfoodluva]

Hopetoun Park is just east of Bacchus Marsh, and about 15 nautical miles from Tullarmarine. Aircraft arriving from the west, and landing on 34 would be about the only ones that would fly closely by you on arrival. As they pass, they'd have about 25 miles to run, and would be about about 6,000 feet.

As a rough guide to heights on descent...10 miles to run, 3,000 feet (190 knots). 20 miles, 5,000 feet (250 knots). Further out...about the distance to run (in miles) times 3.2 will give the height in thousands.

Thanks for your answer JB. My pretty pathetic guess was in between 2 to 3000 feet! Thanks for your time in answering our questions; I love reading this thread.

 

[sdhog2002]

Very great thanks to you from me to, JB. Your kind informative responses are greatly appreciated.

 

[mjt57]

JB, as your work involves only long haul flights, what is the attraction of that over say, domestic ops, other than the money (flying A380s)?

Do domestic pilots get to sleep in their own beds on a more regular basis?

And I can only imagine how complex the scheduling for pilots is to manage it all.

 

[Melburnian1]

After I posted this in another thread, mannej kindly suggested that I ask it here.

While obviously not identical from year to year, with what rough frequency do go arounds (missed approaches) occur at each major Australian airport - are we talking 10 a month if that when the weather is good and stable, but many more when it isn't?

Of BNE, SYD, MEL and PER, what would be the ranking for the number of these incidents? There appeared to be one this morning at MEL involving CA177 ex PVG.

 

[Robbi]

Hopetoun Park is just east of Bacchus Marsh, and about 15 nautical miles from Tullarmarine. Aircraft arriving from the west, and landing on 34 would be about the only ones that would fly closely by you on arrival. As they pass, they'd have about 25 miles to run, and would be about about 6,000 feet.

As a rough guide to heights on descent...10 miles to run, 3,000 feet (190 knots). 20 miles, 5,000 feet (250 knots). Further out...about the distance to run (in miles) times 3.2 will give the height in thousands.

Maybe I haven't woken up, but it seems at 30 miles I should be at 96,000 feet?

Interesting 91,000 foot descent over 10 miles to reach to 5,000 feet at 20 miles ;-)

 

[straitman]

After I posted this in another thread, mannej kindly suggested that I ask it here.

While obviously not identical from year to year, with what rough frequency do go arounds (missed approaches) occur at each major Australian airport - are we talking 10 a month if that when the weather is good and stable, but many more when it isn't?

Of BNE, SYD, MEL and PER, what would be the ranking for the number of these incidents? There appeared to be one this morning at MEL involving CA177 ex PVG.

From the perspective of the pilot a go around/missed approach is a total non event an certainly not an incident so I really do not understand your obsession with it.

 

[Fruitcake]

While obviously not identical from year to year, with what rough frequency do go arounds (missed approaches) occur at each major Australian airport - are we talking 10 a month if that when the weather is good and stable, but many more when it isn't?

Civil Aviation Safety Authority - Go-arounds
"In Australia, over 800 standard go-arounds are performed in a typical year. On average, that’s more than two on any given day at an airport or aerodrome somewhere around the country."

 

[RooFlyer]

From the perspective of the pilot a go around/missed approach is a total non event an certainly not an incident so I really do not understand your obsession with it.

Rather unkind, if I may say so. This thread is for non pilots to ask the pilot(s). Our 'obsessions' tend to be about all sorts of things pilots regard as mundane and 'non events' but are usually beared with even when questioners use the incorrect terminology.

As a passenger, a go-around is one of the more frightening experiences of routine travel; we know take-off / landing is the most 'at risk' part of the journey; something has either 'gone wrong' or is 'not right', but we have no idea of what's going on until the flight crew have an opportunity to tell us.

I too am curious about the frequency of such events in Australia and if any Australian airport, for whatever reason, tends to have more than its peers.

Edit: thanks for that link fruitcake; wonder how the major airports vary, if at all?

 

[straitman]

Rather unkind, if I may say so. This thread is for non pilots to ask the pilot(s). Our 'obsessions' tend to be about all sorts of things pilots regard as mundane and 'non events' but are usually beared with even when questioners use the incorrect terminology.

As a passenger, a go-around is one of the more frightening experiences of routine travel; we know take-off / landing is the most 'at risk' part of the journey; something has either 'gone wrong' or is 'not right', but we have no idea of what's going on until the flight crew have an opportunity to tell us.

Point taken however JB has answered this at least once previously as have I.

It is not a complex procedure and it is simply a case of apply power, raise the aircraft nose, wheels up and flaps up (maybe in stages) and you are now in the after takeoff profile. This is something that a pilot must learn and master prior to going on their first solo which is in the 10-15 hours flying range.

 

[D747]

jb, going back to the QF 30 incident, in the ATSB report it says: "After clearing the baggage and cargo from the forward aircraft hold, it was evident that one passenger oxygen cylinder (number-4 from a bank of seven cylinders along the right side of the cargo hold) had sustained a sudden failure and forceful discharge of its pressurised contents into the aircraft hold." But from what I understand from this: "While it was hypothesised that the cylinder may have contained a defect or flaw, or been damaged in a way that promoted failure, there was no evidence found to support such a finding. Nor was there any evidence found to suggest the cylinders from the subject production batch, or the type in general, were in any way predisposed to premature failure." There has never been a clear picture as to what made this particular cylinder fail, has there? Are these cylinders in an area of the aircraft that is accessed by ground staff or only by mainteinance staff? Thanks for this amazing thread.

 

[markis10]

I too am curious about the frequency of such events in Australia and if any Australian airport, for whatever reason, tends to have more than its peers.

There is no real data kept because there is no need, unlike landings and take offs there is no charges involved. I would hazard a guess that secondary airports would have a higher incidence than primary airports given the skill sets involved, it's certainly my observation having worked in the towers of both. In fact on a shift at Bankstown as the training circuit controller, I could issue six to ten go rounds in a period of six hours, at Sydney I might see one.

Of course at Bankstown there is a lot more happening with a movement every thirty seconds in good weather.

 

[markis10]

There was a recent discussion about flying in retirement, for some there are a lot of good reasons not to, including ones holding guns:



http://www.news.com.au/travel/trave...ted-in-indonesia/story-fnizu68q-1226886805818

 

[OzEire]

On my flight today (VA E190) there was a person dressed as a civilian, ie. not in uniform, travelling in the coughpit jumpseat. My first guess was perhaps staff repositioning, but there were 2 VA cabin crew travelling in Y, in uniform, and lots of spare seats in J.

So who would get a ride in the jumpseat when cabin seats are available?

 

[Orca]

On my flight today (VA E190) there was a person dressed as a civilian, ie. not in uniform, travelling in the coughpit jumpseat. My first guess was perhaps staff repositioning, but there were 2 VA cabin crew travelling in Y, in uniform, and lots of spare seats in J.

So who would get a ride in the jumpseat when cabin seats are available?

Could be anyone flying as what's known as an 'Approved Technical Observer'

For instance, us pesky air traffic controllers do such jump seat flights every now and then to give us an insight to things from a pilots perspective.