Ask The Pilot

[jb747]

When a jet completes a journey and is re-fuelled is it ok to just top up the tanks or do they need to remove the left over from the previous trip. Who is in charge of making sure the plane has the correct amount for its next journey? Are you aware of any cases where a fuel gauge was off and a plane departed without correct fuel reserves?

Fuel remaining in the tanks is used on the next flight. We sometimes have to consider it, because some fuels have higher freeze points than others, so the worst freeze temperature limit has to be used until the remainder is sufficiently diluted (or used).

When an aircraft will be taking a very large amount of fuel, on a well established route (i.e. the 93), engineering will pre-fuel the aircraft to about 80% of the average load. The remainder doesn't go on until the Captain decides upon the final loading.

Engineering are given the fuel order, and they put that on board. They don't disconnect the hoses until the crew tell them that they are happy with the load. At the end of the day, though, the Captain is responsible for the fuel.

There are many parts to the refuelling system, so I don't think the 'gauge can be off'. Part of the system may not work, in which case the tank level will have to be physically checked. I've never heard of problems close to home, but of course they have happened many times on ACI.

Possibly a bigger problem than not having enough fuel is mismanagement, or fuel system issues. It's quite possible to run engines out of fuel whilst the aircraft still has plenty on board...it just has to be in the wrong tank. Again, I don't know of anyone doing that, but it wouldn't be hard.

 

[mjt57]

about 50,000 five year olds (of all ages) are looking back and wishing they had my seat. And some of them will get it.

Hopefully not while you're still in it...

 

[Must...Fly!]

Possibly a bigger problem than not having enough fuel is mismanagement, or fuel system issues. It's quite possible to run engines out of fuel whilst the aircraft still has plenty on board...it just has to be in the wrong tank. Again, I don't know of anyone doing that, but it wouldn't be hard.

Perhaps not exactly what you describe, but a somewhat similar incident (which was featured on ACI) - fuel leak on one side, which led to an imbalance. The pilots did not know of the fuel leak so went and pumped fuel from the good tank to the leaking one. Air Transat Flight 236 - Wikipedia, the free encyclopedia

 

[jb747]

Perhaps not exactly what you describe, but a somewhat similar incident (which was featured on ACI) - fuel leak on one side, which led to an imbalance. The pilots did not know of the fuel leak so went and pumped fuel from the good tank to the leaking one. Air Transat Flight 236 - Wikipedia, the free encyclopedia

Actually I just thought of someone who managed it in an A380. Not my mob.

The Airbus fuel system is basically automatic, and generally pretty smart. But, like so much of Airbus, it either shuts down, or behaves 'differently' with relatively minor failures.

The whole story of Air Transat 236 is very odd. It was a nice save, after an incredible screw up. Basic common sense says that you look to see what the fuel is actually doing. Fuel leaks aren't common, but they certainly aren't unknown, and a strategy for handling them should be a very basic part of your mental flight bag.

Issues with fuel systems happen. 99% of the time the crew simply make them go away, either by coming up with an alternative strategy that gets them the fuel, or by going without, and managing the flight with the 'new' available fuel. That's the word you have to consider...available. A couple of years ago, we lost both transfer pumps from the stab tanks. That initially trapped about 14 tonnes in the tail, and would give both CofG and total fuel issues if not resolved. The Airbus procedure to resolve it only partially worked, so it took a little lateral thinking to help the cause. We tried descending a bit, and going very fast, which gave a lower pitch attitude and a better gravity transfer from the tanks. Whilst that didn't recover all of the fuel, it got enough to allow flight to destination. But, whilst that odd transfer was happening, we ONLY considered fuel in the main tanks for all of our decisions. It's very basic stuff.

 

[richie9x]

Would you ever get the case where the plane has been overfilled with fuel? Say a plane has been fueled to get to LAX and then it is swapped to fly to Singapore. Does that ever happen? If so would they empty the excess fuel? Or just fly with the extra fuel and just recalculate everything to take that into account?

 

[jb747]

Would you ever get the case where the plane has been overfilled with fuel? Say a plane has been fueled to get to LAX and then it is swapped to fly to Singapore. Does that ever happen? If so would they empty the excess fuel? Or just fly with the extra fuel and just recalculate everything to take that into account?

Most over fuelling is minor...less than a tonne. But, even that can be a problem if you're planned for a take off at max weight. In that case you'll just start up and burn the fuel down to the amount you need.

Defuelling does happen, though I've never seen it. The scenario you suggest would throw up the need, as the LA fuel load is so much greater than the Singapore load that you'd be above max landing weight when you arrived. They wouldn't take out all of the fuel though, only enough to get the weight to something reasonable.

If the additional fuel didn't cause any limits to be hit, it would be much more convenient to just take it. Pilots like extra fuel anyway.

 

[mjt57]

Actually I just thought of someone who managed it in an A380. Not my mob.

The Airbus fuel system is basically automatic, and generally pretty smart..

Are you able to manually operate it; ie. move fuel from one tank to another if the need arises?

What happens if a valve fails, say it torques out, or whatever? Can it be reset from the flight deck is will it remain U/S until you land and maintenance can look at it?

 

[jb747]

Are you able to manually operate it; ie. move fuel from one tank to another if the need arises?

It can all be moved manually if needed.

What happens if a valve fails, say it torques out, or whatever? Can it be reset from the flight deck is will it remain U/S until you land and maintenance can look at it?

I've never seen a valve fail to move when commanded, but pumps shut themselves down fairly regularly. You never attempt to reset anything that's immersed in fuel, or in a tank. Everything, including the plumbing, is duplicated, and some of the tanks will also gravity transfer.

The failures that could occur and trap fuel would happen at heavy fuel states. As the load lessens, and the loss of a tank of fuel becomes more important, it concentrates into the main tanks, and they will gravity feed if necessary.

 

[spudwa]

I live 10 km from the south end of the 03 runway. 20 years ago when we bought the house noise wasn't a problem but with the rise of FIFO traffic its getting bad. The last few days have been very bad and I'd like to ask a pilot when and why do they use different approaches from the south. I call it the long approach over my house or the short one where they fly in from the east and turn about 8 km from the threshold. Guess which one I prefer?

 

[AVC]

The whole story of Air Transat 236 is very odd. It was a nice save, after an incredible screw up. Basic common sense says that you look to see what the fuel is actually doing. Fuel leaks aren't common, but they certainly aren't unknown, and a strategy for handling them should be a very basic part of your mental flight bag.

I remember this one. The dead giveaway was the fact that one engine had high oil pressure (I think maybe combined with low oil temp).

Fuel leaks - evaporates - causes cooling (same as evaporating sweat cools the body) - oil is colder, more viscous - pressure goes up.

So the question is - would the pilots normally monitor those type of engine functions nowadays, or does the system do it and sound an alarm if it goes out of limits?

 

[jb747]

I remember this one. The dead giveaway was the fact that one engine had high oil pressure (I think maybe combined with low oil temp).

Fuel leaks - evaporates - causes cooling (same as evaporating sweat cools the body) - oil is colder, more viscous - pressure goes up.

I'd have thought that the fuel level steadily drifting away from the planned would be an even better indicator.

There are multiple heat exchangers, and using fuel to cool the oil, whilst simultaneously warming the fuel is the norm. So, you normally see the oil temperature rise when in a descent, as there is less fuel flow through the exchanger.

I don't think your comment about about the evaporation is correct (at least in relation to this event). I expect there was an increased fuel flow to the leaking engine manifold, so more fuel through the exchanger = cooler oil.

So the question is - would the pilots normally monitor those type of engine functions nowadays, or does the system do it and sound an alarm if it goes out of limits?

If the parameters hit the limits it will set off and EICAS/ECAM. In cruise we have a look at all of the parameters every 20 minutes or so. Aircraft like the 380 are also monitored by maintenance, and RR, and I expect their computer monitoring would be very interested in trends.

 

[jb747]

I live 10 km from the south end of the 03 runway. 20 years ago when we bought the house noise wasn't a problem but with the rise of FIFO traffic its getting bad. The last few days have been very bad and I'd like to ask a pilot when and why do they use different approaches from the south. I call it the long approach over my house or the short one where they fly in from the east and turn about 8 km from the threshold. Guess which one I prefer?

I assume you're talking about Perth.

I haven't flown there for a long time, but if I recall correctly, approaches from the east have their descent constrained by the hills, so it can be quite difficult to legally fly the approach you prefer. Some aircraft types are better able to handle a vertical offset than others. Generally the bigger, the less able.

Plus, of course, if the weather is even slightly iffy, you need to fly the complete approach, not just the last bit.

As a general rule, any procedure that is put in place to reduce noise, always reduces safety as well.

 

[spudwa]

Sorry yes I'm talking about Perth YPPH. I've done some research of my own and it looks like the ILS approach starts 10NM out at TIMMY where as the shorter "visual" approach is GOSNL. We've had a lot of cloud over the last few days so thats probably why

 

[Must...Fly!]

JB, if lightning strikes the aircraft on departure, what is the normal procedure, is it to continue to destination and deal with any possible problems there or to dump fuel and land at the origin port? If there is such a procedure is that company policy & does it vary between airlines?

I have searched but not found an answer which surprised me as I recall lightning discussion multiple times in the thread.

 

[Major]

During your SIM sessions do you have a regular line FO with you, who is also being assessed, or are the FO's specialist SIM trainers ? Also does your session include a SO ?

 

[jb747]

JB, if lightning strikes the aircraft on departure, what is the normal procedure, is it to continue to destination and deal with any possible problems there or to dump fuel and land at the origin port? If there is such a procedure is that company policy & does it vary between airlines?

I have searched but not found an answer which surprised me as I recall lightning discussion multiple times in the thread.

Lightning is generally a non event. Unless we had other failures, I wouldn't even consider landing because of a lightning strike. Mostly it does little to zero damage, with the most common being some marks on the paint.

 

[jb747]

During your SIM sessions do you have a regular line FO with you, who is also being assessed, or are the FO's specialist SIM trainers ? Also does your session include a SO ?

Sessions are normally paired with both of us doing our renewals. If there is a late change, you may have somebody who is just supporting, but again, normally a line pilot. SOs do their own sessions and are not involved in the Captain/FO renewals.

 

[RooFlyer]

Hello

When navigating the taxi-ways etc (say of large airports and at night), do you follow light signals or guidance from ATC (or its Ground Control equivalent) or both? Do 'wrong turns' occur and if so, are there consequences for the pilot? If there is a 'wrong turn' taken, who would realise first - the pilot or ATC/GC?

I ask having recently had a seemingly interminable taxi after landing and we seemed to go right in a circle, as if we had gone to a wrong place and had to 'go around'.

 

[mannej]

Ask The Pilot

There have been a few crashes that have occurred due to wrong turns on taxiways (The Milan Linate collision and SQ006 are two examples).

 

[jb747]

Hello

When navigating the taxi-ways etc (say of large airports and at night), do you follow light signals or guidance from ATC (or its Ground Control equivalent) or both? Do 'wrong turns' occur and if so, are there consequences for the pilot? If there is a 'wrong turn' taken, who would realise first - the pilot or ATC/GC?

I ask having recently had a seemingly interminable taxi after landing and we seemed to go right in a circle, as if we had gone to a wrong place and had to 'go around'.

These can be some of the most dangerous errors in aviation. Misidentified turns, that put aircraft onto, or in very close proximity, to runways, have caused quite a few bad accidents over the years. Of course, most ground errors are simply a bit embarrassing. One I recall from JFK had a 777 start a turn into a taxiway that had a max size limit of 737/320. The 777 pilots realised, but did not have enough room to extricate themselves, with the result that they blocked the huge queue on the way to the runway. It worked to my advantage, as I was behind him in the line, and was able to jump from about number 87 to number 3.

Hong Kong has had a number of attempts to take off on the parallel taxiways. Hard to work out just how this is done, as the lights are totally 'wrong', but it's happened more than once.

In the past, most airports used blue taxiway edge lighting only. There was no aircraft specific guidance. They tended to look like a sea of blue, and it was quite hard to visualise the route. This has slowly changed, with blue lighting giving way to green centreline, and then that being modded so that it is only on for your route. Of course, this only works in daytime. The advent of 'stop bars' (discussed earlier in the thread), is a great aid to keeping aircraft out of areas that they shouldn't be.

I expect routing errors are discovered more or less equally by the crews and ATC. What you see as going around in a circle, could well be, but equally, it's quite possible that the most direct route was blocked by other traffic, or had some other restriction. Late gate changes are also problematic...the aircraft don't back well.