Ask The Pilot

[RooFlyer]

I had one for a couple of years, but I removed it when it started attracting unwanted attention. A couple of the videos had over half a million hits.

They were brilliant videos as well.
<snip>.

Hear, hear!! Very much hoping JB might venture into that space once more.

 

[AVC]

Is duct tape used often to fix planes?

Reminds me of this one:



If it cant be fixed with duct tape....


you're not using enough duct tape!

 

[Kc4334]

I had one for a couple of years, but I removed it when it started attracting unwanted attention. A couple of the videos had over half a million hits.

Oh really that's such a pity oh well thanks for your answer. Any other channels you would recommend?

 

[opusman]

Duct tape saved Apollo 13 after all, I'm sure a 747 is no problem

 

[whatmeworry]

I had one for a couple of years, but I removed it when it started attracting unwanted attention. A couple of the videos had over half a million hits.

Considering you were getting lots of hits, IIRC youtube pay $2000-3000 per million hits.

 

[mjt57]

I had one for a couple of years, but I removed it when it started attracting unwanted attention. A couple of the videos had over half a million hits.

Some are still floating about out there. In particular, watched the one where your FO is doing the arrival into MEL. I think that it was the one where you overflew Essendon. The guy was "fiddling" with some knobs and you told him to "fly the plane" or words to that effect.

Also one where you depart what I think is LHR at night. At least, I think that it was yours.

They came up in the queue after I'd watched an aviation related video.

So, it appears that people have grabbed them and reposted.

 

[jb747]

I found that sort of behaviour was common. Another reason why they are no more....

 

[coriander]

Appropos of jb's videos, I remember being on one QF93 flight departing Melbourne: I was taking photos out the window when I was sternly told to put away my camera - "you're not allowed to take photos" - "yes I am" - "no you're not: your camera (a Nikon D7000 I might add) is an electronic device SO TURN IT OFF AND PUT IT AWAY" - "but there's a youtube video of a pilot's view on Qantas jets" resulted in the classic reply "well there you go, so you don't need to take photos yourself then, PUT IT AWAY".

 

[jb747]

Cameras aren't banned, but they've got you on the unsecured device. Good comeback too.

 

[coriander]

Good comeback too.

yes, I thought so too, hence my smileys - I took it all in good humour but Mrs C was worried I would be labelled a troublemaker in QF's database.

 

[flychrisfly]

Hi JB

You mentioned previously about 'hi energy descents'. I had assumed that meant a descent that required a steeper than usual descent angle, a faster velocity or both, but could you clarify please?

How does a high energy descent come into play in stepped vs continuous/smooth descents?

Thanks!

 

[jb747]

Hi JB

You mentioned previously about 'hi energy descents'. I had assumed that meant a descent that required a steeper than usual descent angle, a faster velocity or both, but could you clarify please?

Energy generally becomes a problem in close proximity to an airfield. Think back to your high school physics, and there are two components we have to worry about. Kinetic energy is related to speed squared, whilst potential energy is related to your height, and is a linear relationship. The aircraft total energy is the sum of the two.

You can be in a high energy situation by being faster than normal at a given point on the arrival, or by being higher than normal. You only need to be 40% faster than usual to have double the kinetic energy, so fast is always the more difficult to fix. ATC, particularly in the USA, have a very nasty habit of simultaneously wanting higher speeds whilst 'holding you up', by not giving you descent on profile. End result, if you don't baulk, is perhaps ending up higher and faster than normal, with only a few miles to run. This was part of the Aseana situation in SFO...

On all arrivals, the FMC is constantly calculating the distance to run, and you can catch yourself out if you rely totally on that, and don't consider the implications of ATC suddenly shortening the arrival track. Whipping 10 miles out of the arrival, when you only have about 25 to run, will instantly convert a normal energy state to a high energy one. You can probably pick this from the cabin, as the solution is generally to extend the landing gear, for the maximum drag possible.

How does a high energy descent come into play in stepped vs continuous/smooth descents?

When descending, we have a range of options that we can use. More drag can be generated by use of the speed brakes, and that will yield a steeper descent at any given speed. Simply going faster will also give a steeper descent (though we generally don't have a great deal of speed margin). Slower will make the descent shallower, as we'll be closer to the min drag speed of the aircraft. Any descent that is allowed to stick to the plan, even if fast, should be smooth. But, if ATC make us deviate from the plan (i.e. it's a normal day), we'll either have to put more energy into the descent (i.e. by using power), or more drag. Both will have the effect of making the entire process less smooth, and will ultimately have to be countered by the opposite action as well (i.e. more power will start to make us higher than the plan, and will need either more drag or more miles).

There's not much use for 'high energy' descents in normal operations, and many airlines include speed limits at various heights to limit just how much speed you can carry. But, if you are really up against a curfew, and you want that last second, then a planned descent with full speed brakes and at max speed, will give the steepest arrival and the maximum groundspeed. And it will also require the seat belts for the entire descent, with the cabin crew already finished, so it can't just be done off the bat.

 

[flychrisfly]

Hi JB

I've only just noticed (was it newly added?) your Flight Map. I'm guessing that it contains one of every route you've ever been on. Does it include all flights with you in the coughpit and down the back or...?

Cheers

 

[jb747]

Hi JB

I've only just noticed (was it newly added?) your Flight Map. I'm guessing that it contains one of every route you've ever been on. Does it include all flights with you in the coughpit and down the back or...?

It's only sectors as operating crew. Probably not complete, but close enough.

 

[Captain Halliday]

During the safety briefing at the part about oxygen masks, the video or CSM usually says something along the lines of, "...the bag may not inflate but oxygen will flow through the bag."

If not for inflation, what is the function of the bag?

 

[jb747]

During the safety briefing at the part about oxygen masks, the video or CSM usually says something along the lines of, "...the bag may not inflate but oxygen will flow through the bag."

If not for inflation, what is the function of the bag?

Good question, to which I don't have a definite answer. The cabin crew will pinch the exit side of the bag to check for flow, and it may be that it's a simply way to provide that function.

 

[woodborer]

The idea is that oxygen will flow whether the bag inflates or not. The addition of the text was due to a safety issue related to "Inadequate passenger safety briefing about oxygen masks" that surfaced during the investigation of QF30.
.
Safety issue: AO-2008-053-SI-02 - Inadequate passenger safety briefing about oxygen masks

 

[anat0l]

During the safety briefing at the part about oxygen masks, the video or CSM usually says something along the lines of, "...the bag may not inflate but oxygen will flow through the bag."

If not for inflation, what is the function of the bag?

From the information I can gather on the web, not everyone seems to be clear on what the exact function is (except those that designed it in the first place).

Most agree, however, that the bag is intended to be a rebreather chamber, i.e. the oxygen flow is continuous but your breathing is not, so the bag helps regulate the inhalation of oxygen. I guess that makes some sense, as when (in most cases) you apply the oxygen mask after they are deployed, it is not as if you are immediately oxygen-deprived and/or have a failure in breathing, and this is why oxygen rescue systems with paramedics etc. don't necessarily have rebreather chambers, because it's just important to get oxygen into the person posthaste - this is not the objective when the oxygen masks come down in an aircraft.

I don't have much idea why the bag may or may not inflate; my guess it has something to do with the altitude and thus ambient pressure; should be fairly easy for those with competencies in physics and/or chemistry to explain this one, but right now it's not coming to me.

Anyway, part guess, part research - happy to hear a more official answer.

 

[jb747]

The idea is that oxygen will flow whether the bag inflates or not. The addition of the text was due to a safety issue related to "Inadequate passenger safety briefing about oxygen masks" that surfaced during the investigation of QF30.
.
Safety issue: AO-2008-053-SI-02 - Inadequate passenger safety briefing about oxygen masks

Well, yes...the issue on the 30 was that because the bag did not inflate, some people thought they had no flow. But, given that the masks are open to the cabin anyway, and don't seal like the pilots' masks...then what is the exact purpose (of the bag). Or is there there one at all? Dunno.

 

[coriander]

Most agree, however, that the bag is intended to be a rebreather chamber, i.e. the oxygen flow is continuous but your breathing is not, so the bag helps regulate the inhalation of oxygen.
I don't have much idea why the bag may or may not inflate

The bag won't inflate immediately, but will eventually inflate as the steady flow of oxygen wil exceed the respiration rate of the passenger especially once they stop screaming. Also the fit of the mask will probably be imperfect which will allow excess oxygen to spill out of the bag and take expired carbon dioxide with it.

I guess the staff say "may or may not inflate" to calm passengers who are really breathing very deeply or who haven't well fitted their mask: one less reason for a passenger to press the call button.