Ask The Pilot

[jb747]

VH-OJS late out of JFK will arrive at 1110 into SYD.

apparently a starter motor had to be replaced. Part came from BA plane according to a friend on the flight.

What are these starter motors for? And are parts swopping a common practice?

The engines use air driven starters. They spin the engine core spool up to about 25%, at which point fuel is introduced, and they become self sustaining. If you could tow it down the runway at about 220 knots, you could do a start without the starter.....

I'm sure the part did not come off a BA aircraft. But, it could well have come from BA's spares at JFK (same as I got an IRU from Emirates recently). Airlines sometimes band together and have a supply of pool parts, but sometimes needed parts come from local airline stores. In any case they are basically rented from the supplier, and in the case of other airlines (as opposed to the pool) normally must be returned within a very short period.

 

[mikenz]

What degree of bank can a large aircraft (A380/B747) manage, what would be the maximum degree of bank on a typical flight?

 

[jb747]

What degree of bank can a large aircraft (A380/B747) manage, what would be the maximum degree of bank on a typical flight?

Airliners typically have a limit of 2.5g, which would be achieved with a 67º angle of bank (level) turn. The FBW systems also limit bank, to about that figure too, with the force required hold a given bank angle increasing once a few degrees past 30º.

In normal ops though, the passengers tend to dislike being crushed to the floor under a couple of times their own weight...so the most you'll see is about 30º (1.15g). Most turns are even less than that....about 15-20º.

G load is equal to 1/(cos(angle of bank).

 

[mikenz]

Thanks JB.

Passenger comfort aside, woulf the aircraft be able to fly inverted? What would be the impact on performance?

 

[jb747]

Thanks JB.

Passenger comfort aside, woulf the aircraft be able to fly inverted? What would be the impact on performance?

Passenger comfort.....??

Assuming you could get past the flight control restriction on 67º angle of bank, and get to 180º...I'm not sure that you'd actually have enough forward control available. If you did, then it would soon become very quiet, as the engines would not have any fuel fed to them after the first few seconds.

 

[clazman]

Isn't there a story of a RAF Boeing returning from the gulf war doing a wing over?

 

[jb747]

Isn't there a story of a RAF Boeing returning from the gulf war doing a wing over?

One of the problems with writing these replies is trying to ensure that we are both talking about the same thing. In the previous questions about angle of bank and inverted flight, I've assumed that a stable situation was being discussed, i.e. level inverted flight, or a constant high bank turn.

A wing over is a very simple, and low g manoeuver, that can be done in virtually any aircraft. Much the same as barrel roll, which, when done correctly, is also within the abilities of a wide range of aircraft (and it was famously done in the initial 707 models by the Boeing chief test pilot). In very simple terms, a wing over simply involves pitching up to a reasonably steep attitude, rolling the aircraft to 90º or so, and then letting the nose fall to somewhere around the horizon, and then rolling the bank off.

 

[clazman]

Generally speaking is there a breakeven point on a flight, where if you have say 75% seats full it is profitable?

 

[Boris spatsky]

Might be more relevant in the 'Ask The Accountant' thread.

I have no idea. It comes up as a discussion point on a slow day but we have no visibility of that side of the operation at all.

 

[jb747]

Generally speaking is there a breakeven point on a flight, where if you have say 75% seats full it is profitable?

The costs of any given flight vary quite a bit, so there's never really a fixed cost per passenger. As for load factor, 75% across the aircraft might be around break even, but if that's full in economy but empty in first and business, then you'll never break even. On the other hand, a good premium load means that economy can be very light.

 

[por930]

Hi JB,
I presume the flight path is input by the company, and you check it on preflight and modify with runway, SID and STAR as required.
Do you both together check each waypoint from the plan against the FMC.
What would be the approximate distance between each of the ocean waypoints? When I checked on flightaware, some of the 19 oceanic fixes, if they got them all and were correct, looked very far apart.

I recently flew on QF7 15.15 hrs/QF8 16.35 hrs, we were in the pointy end so the long flight was excellent. It amazed me how quite the A380 aircraft is inside compared with 747 and 777 we also recently flew on.

 

[Quickstatus]

JB,

Could you please opine on the link below - its about a 777 captain's view on the possible cause(s ) of MH380 disappearance.

No Cookies | dailytelegraph.com.au

 

[jb747]

JB,

Could you please opine on the link below - its about a 777 captain's view on the possible cause(s ) of MH380 disappearance.

No Cookies | dailytelegraph.com.au

I think it proves there are a lot of idiots on the web. Even the main article is riddled with inconsistencies, and the letters are something else.

 

[jb747]

Hi JB,
I presume the flight path is input by the company, and you check it on preflight and modify with runway, SID and STAR as required.
Do you both together check each waypoint from the plan against the FMC.

Normally the route is uplinked at the start of the preflight. We separately check it against the route summary. Runway and SID are added after we get the ATIS. Sometimes an arrival is loaded early in the flight, though as often as not, it's left until about 20 minutes prior to descent.

What would be the approximate distance between each of the ocean waypoints? When I checked on flightaware, some of the 19 oceanic fixes, if they got them all and were correct, looked very far apart.

Mostly about 400 miles. Across the Pacific it's all data link.

 

[jb747]

Laser..

Had my first experience of someone pointing a green laser at the aircraft last night. It wasn't close to us, but still bright enough to be an issue when the dunce behind it managed a hit. But, on the other hand, we happened to be running a 4k camera at the time, so we caught the source position fairly well. Stupid enough to do it once, I'm sure he'll do it again.

 

[QF WP]

jb747, I presume you did an incident report and were able to download the tape from the camera as collateral proof. Does it get reported to CASA as well as Police?

I'd like to shine the laser in their eyes and see how (presumably) he likes it :evil:. Hope his parents are suitably unimpressed and that the police visit to home scares the little cough so he doesn't do it again.

 

[TomVexille]

Laser..

Had my first experience of someone pointing a green laser at the aircraft last night. It wasn't close to us, but still bright enough to be an issue when the dunce behind it managed a hit. But, on the other hand, we happened to be running a 4k camera at the time, so we caught the source position fairly well. Stupid enough to do it once, I'm sure he'll do it again.

If these sort of people get caught I hope they are charged with attempted murder of however many people are onboard the respective aircraft...

 

[anat0l]

If these sort of people get caught I hope they are charged with attempted murder of however many people are onboard the respective aircraft...

See this is the thing. People would think that attempted murder or manslaughter would be far too extreme a punishment, but if one plane happened to go down, then what do they have to say?

OK, so they are saying, "but the plane didn't go down?" Alright, what about the eye damage to the pilot? (And so on).

Not wishing to turn this thread into one of the other laser threads (can split off if it gets that far), I hope that jb747 is OK and there is swift follow up to the reported incident.

 

[CaviAck]

Laser..

Had my first experience of someone pointing a green laser at the aircraft last night. It wasn't close to us, but still bright enough to be an issue when the dunce behind it managed a hit. But, on the other hand, we happened to be running a 4k camera at the time, so we caught the source position fairly well. Stupid enough to do it once, I'm sure he'll do it again.

GoPro 4?

I hope you nor any of the other pilots in the cabin nor anyone for that matter aren't affected in anyway.

 

[jb747]

Nobody was harmed. It was an interesting lesson in just how distracting one of these things could be. And yes, it was a 4K GoPro.