Fuel Burn at Different Altitudes

[Chief Captain]

If that situation comes up, I'd rather tell the controller that I'm able FL380, but would prefer to stay at 360.

What it really comes down to is the lesser of 2 evils- FL380 vs FL340. I find that taking the time to explain why I'm unable to do something makes it less likely that I'm gonna look like a liar when I go back and say that I can do it.

 

[Vector4Food]

I do actually have qualms with that. Sometimes if FL380 is right on the edge (but safe), it's better to try to see if it's possible to maintain FL360 and see if the controller has another plan. If the plan is to descend, it's sometimes better to take the climb. Remember, we're the ones with the limited fuel supply, and don't have access to "The Plan." Descending the aircraft further just out of spite... Well... I think it'd be wise not to respond to that.

The point is, nobody's trying to lie to you, screw with you, or trick you. We're just trying to do what's best for the flight.

I've got no issue with that, just don't say unable, if you're unable you're unable. If we're asking you for traffic, you should assume you're going to get moved up or down, so if you don't want to climb then say that, if you don't want to descend either, well sorry but someone has to move.

 

[Vector4Food]

Matter of fact, if we're asking at all there's a reason. We are busy enough, we don't go around making extra transmissions for fun.

 

[s60]

I don't mind when pilots tell me they are able, but would rather not, climb. If it's not too busy, I will then ask the other guy if he's able to climb, and decide based on his response who's going where. If I only have one other plane to get you past, I will likely ask if you want to go back to the original altitude if I get the 5 miles separation I need in my airspace, or if not and it's not too busy, I might even pass on your request to go back down to the next sector.

 

[TripSix]

I had a Captain accept a dispatch with just about the absolute minimum fuel required for a 3+ hour flight. After raising my concerns, I'm told "it'll be fine". 20 minutes after takeoff, he's arguing with ATC because we're stuck at FL240.

I couldn't help but side with the controller on that one. Apart from the obvious separation issue, it's kind of silly to accept a fuel load so low that a few minutes below the planned level causes significant anxiety.

I think you'd be shocked how often this happens.

Or, maybe you wouldn't.

 

[greg1016]

I do actually have qualms with that. Sometimes if FL380 is right on the edge (but safe), it's better to try to see if it's possible to maintain FL360 and see if the controller has another plan. If the plan is to descend, it's sometimes better to take the climb. Remember, we're the ones with the limited fuel supply, and don't have access to "The Plan." Descending the aircraft further just out of spite... Well... I think it'd be wise not to respond to that.

The point is, nobody's trying to lie to you, screw with you, or trick you. We're just trying to do what's best for the flight.

As usual, I agree with my Canadian colleague. I would not have issued a clearance at all or asked you at all if you are able higher if the altitude you are presently at were acceptable. If you are asked (or cleared) if you are able higher due to traffic and you reply unable, then you should expect a descent. Sometimes I'll ask if you are able higher because an aircraft that is under you is requesting higher, in this instance I will not use "due to traffic" but if you get a "due to traffic" and you reply unable, you can expect a descent. Remaining separated with other traffic is always what is best for the flight.

 

[dasleben]

As usual, I agree with my Canadian colleague. I would not have issued a clearance at all or asked you at all if you are able higher if the altitude you are presently at were acceptable. If you are asked (or cleared) if you are able higher due to traffic and you reply unable, then you should expect a descent. Sometimes I'll ask if you are able higher because an aircraft that is under you is requesting higher, in this instance I will not use "due to traffic" but if you get a "due to traffic" and you reply unable, you can expect a descent. Remaining separated with other traffic is always what is best for the flight.

That's not the issue. The issue is pushing the aircraft even lower than necessary just to "get back" at them, as in the example.

 

[Chief Captain]

I can't say I've ever thought I was being punished by a controller. I try and make their jobs as easy as I can manage.

Wait, I take that back, there was one instance in ORD where I thought the controller got unnecessarily pushy, but what can you expect from ORD?

 

[dasleben]

I can't say I've ever thought I was being punished by a controller. I try and make their jobs as easy as I can manage.

Same. I'd consider any games used to "punish" a controller in some way a serious breach of professional integrity.

 

[greg1016]

I'm not going to punish an aircraft, even though sometimes I'd like to, but I have to devise and implement a plan. I try my best to keep everyone as happy as possible. When time is of the essence, if you answer unable and another aircraft is able than the other aircraft gets the altitude, if you answer able but requesting present altitude, then I will try not to issue a descent. For instance, maybe I need you level in an hour and a half, not immediately. I'll give you the restriction to be level in an hour and a half, and you can take your sweet time getting there.

 

[dasleben]

I'm not going to punish an aircraft, even though sometimes I'd like to, but I have to devise and implement a plan. I try my best to keep everyone as happy as possible. When time is of the essence, if you answer unable and another aircraft is able than the other aircraft gets the altitude, if you answer able but requesting present altitude, then I will try not to issue a descent. For instance, maybe I need you level in an hour and a half, not immediately. I'll give you the restriction to be level in an hour and a half, and you can take your sweet time getting there.

I completely understand all of that, but as I said, that was never my issue.

 

[Vector4Food]

I just want to be clear here, that I'd rather give a short 1-2 minute vector than jostle around flight levels, it's just easier sometimes especially for sequencing.

I've only personally seen planes punished once maybe twice, I'm too accommodating for my own good usually.

 

[rframe]

I don't mind when pilots tell me they are able, but would rather not, climb. If it's not too busy, I will then ask the other guy if he's able to climb, and decide based on his response who's going where.

Sounds to me like you guys put too much work into it.

Here's what I'd say:

"ShinyJet00, climb FL380 for traffic"
"We'd prefer to stay at FL360"
"ShinyJet00, Roger, could you please collect the phone numbers of all crew and passengers' next of kin so I know who to call and advise of your demise when you slam into that conflicting traffic in 2 minutes?"

 

[Vector4Food]

I think there's a lot of this stuff which could be fixed by having controllers in the cockpit as often as possible. Rather than a bunch of faceless names ranting on a message board.

More and more crews are so overly concerned about fuel burn, and for good reason, but the controllers job of not welding airplanes together at 900 knots hasn't changed.

 

[greg1016]

I think there's a lot of this stuff which could be fixed by having controllers in the cockpit as often as possible. Rather than a bunch of faceless names ranting on a message board.

More and more crews are so overly concerned about fuel burn, and for good reason, but the controllers job of not welding airplanes together at 900 knots hasn't changed.

I think Bernoulli Fan took a fam trip right after the FAA brought them back, but I haven't yet. I'd love to do it, but they make it such a PITA that it hardly seems worth it. I'd rather just pay for the ticket and take leave to ride in the cockpit than have to go through all the red tape required for a fam trip. That and 0% of the traffic I work is domestic so I can't even fam through my own airspace.

 

[Bernoulli Fan]

I think Bernoulli Fan took a fam trip right after the FAA brought them back, but I haven't yet. I'd love to do it, but they make it such a PITA that it hardly seems worth it. I'd rather just pay for the ticket and take leave to ride in the cockpit than have to go through all the red tape required for a fam trip. That and 0% of the traffic I work is domestic so I can't even fam through my own airspace.

I did take a fam on UAL last year and I had a good time. While the program isn't what is used to be prior to 9/11, it is still a good educational tool, if not a means to an inexpensive vacation. I recommend doing one to everyone who asks. The paperwork isn't that bad.

 

[Vector4Food]

We have fam flights all over the world, but we have no cockpit access yet. Stupid.

 

[FM_Weasel]

So its not really "unable." It's "we'd rather not."

I'll buy that and try to help the pilot when it's possible. But I can really do that if they lie to me.

 

[derg]

We have fam flights all over the world, but we have no cockpit access yet. Stupid.

That is terrible.

Hopefully it'll come back! It'd be good for you guys to see the boredom-PANIC-boredom-EMERGENCY nature of our jobs.


Sent from my TRS-80

 

[dasleben]

So its not really "unable." It's "we'd rather not."

I'll buy that and try to help the pilot when it's possible. But I can really do that if they lie to me.

Gents, there are a number of factors that play into the decision to climb or descend, particularly on a long-haul flight. We're trying to work with you to find the best one. Nobody, and I repeat, nobody is lying to you. In no particular order of importance, here's a non-comprehensive list of factors that can influence the decision to climb or descend:

-Optimum altitude
-Buffet margin
-Fuel burn
-Cloud layers
-Thuderstorms
-Turbulence
-Winds aloft
-Temperature (ISA considerations)
-Fuel temperature (polar routes)

It should be clear that it's not strictly an able/unable decision. If it's annoying that pilots are trying to work out the best altitudes based on these factors, making sure that they have adequate reserves on arrival, I apologize. However, not everything up there is cut and dry, and nobody is screwing with you just for "funsies."