ATCO needs help from pilots: performance data

[twhizzle]

Hi there,

I am an air traffic controller and trainer from Austria and I turn to you for your help.

I am trying to create a document for our trainees that gives a rough overview about performance data of different aircraft types. The idea came up recently when I realized that aircraft performance is kind of difficult to estimate for trainees starting out on the simulator training. With 13 years of working experience, I do know what to expect from most types. But during a recent talk to an A320 pilot a few days ago gave me quite a lot of insight about what is possible vs. what is commonly used, and factors that can contribute to a change in performance limits.
In order to collect data from other aircraft, I would really appreciate if you could take the time and fill out the questionnaire below, which I have already pre-filled with A320 data retrieved from the previously mentioned A320 pilot.

I am aware that some variables are dependent on the circumstances (weight, temperature, ...), but please try to give a rough overview. You can also add complementary information to the numbers if deemed necessary (as did the A320 pilot). I am also very happy to read any other information, besides the questionnaire, to learn more for myself and to forward to my trainees.
Please read footnotes below as well.

1. General info

1.1. Aircraft type (incl. ICAO abbreviation): Airbus A-320 / A320

1.2. Airline (voluntary): Austrian Airlines

1.3. Area operating or common destinations (voluntary): Europe


2. Speeds in common cruising levels

2.1. Common cruising Mach number range: .76 - .80

2.2. Minimum cruising Mach number (1): .69 - .71

2.3. Maximum Mach number: .82 (Never selected more than .81, though, and conditions need to be very smooth for that.)


3. Descend speeds (IAS) below FL 290 down to FL 130

3.1. “Common” speed range during descent: 250 - 310 kts

3.2. Minimum clean speed (1): 215 - 235 kts

3.3. Maximum speed (2): 340 - 350 kts (FL 240-; but generally not above 330 kts)


4. Altitudes

4.1. Ceiling: FL 390


5. Climb performance (optional, see footnote 3)

5.1. Climb performance classification (1-5): 3


Footnotes:

1) Please quote a speed range from minimum clean speed under beneficial conditions (e.g. low tonnage) to the minimum clean speed that’s possible in non-beneficial (e.g. high tonnage) circumstances

2) Maximum IAS possible, usually not above FL 250

3) As ATCO, I have a good overview about that myself from experience. But if you have experience with several types of aircraft yourself and you feel able to do a classification, please use the following method:
1 = really bad (e.g. CRJ1, CRJ2)
2 = worse than A320 (e.g. A321)
3 = A320 and comparable
4 = better than A320 (e.g. B737/738, A319)
5 = very good (e.g. B736, A318, several business jets)
You can also give your estimate in between two classifications (e.g. 2-3).


Thank you very much for your help!

[FlyingStone]

I think Eurocontrol already publishes something similar (https://contentzone.eurocontrol.int/aircraftperformance/default.aspx?).

[twhizzle]

Hello FlyingStone,

Thank you very much for your response!
I do know this database, but unfortunately, it is not very useful in regard to what I am planning to create as it only offers one speed and one climb rate for each flight phase. So far, I have not found a collection of useful data for this purpose. That's why I'd like to collect it myself.

[redsnail]

1. General info

1.1. Aircraft type (incl. ICAO abbreviation): Bombardier Challenger 350S - CL35

1.2. Airline (voluntary):

1.3. Area operating or common destinations (voluntary): Europe +


2. Speeds in common cruising levels

2.1. Common cruising Mach number range: 0.80-0.81

2.2. Minimum cruising Mach number (1): Rarely do minimum ;)

2.3. Maximum Mach number: .82 (Never selected more than .81, though, and conditions need to be very smooth for that.)


3. Descend speeds (IAS) below FL 290 down to FL 130

3.1. “Common” speed range during descent: 285 - 300 kts

3.2. Minimum clean speed (1): 180-200 kts guesstimate

3.3. Maximum speed (2): 300-310 kts


4. Altitudes

4.1. Ceiling: FL 450


5. Climb performance (optional, see footnote 3)

5.1. Climb performance classification (1-5): 5

[twhizzle]

redsnail Thank you very much for participating! Could you check on your next flight what minimum selectable Mach number in cruise level is? I know it is not rarely used, but it would be good to know what is possible (e.g. preparing an inbound sequence before initiating descent). Thanks again!

[FlightDetent]

Then you need to ask what is the lowest Mach we are willing to admit and accept. :-) Not the minimum (limiting) value.

Careful though, the lowest Mach does not really exist. It is the lowest IAS while still in MACH (mode) segment that is limitng. The importnace here is it will be different for the same aircraft in different levels, .72 for my aircraft at FL370, .63 at FL 280 perhaps.

Not to mention different payload weight... (fuel is presumably constant mostly for arrivals to a single destination)

[twhizzle]

Hey FlightDetentent,

thank you for your response and your comments!
I do get your point. From my working experience I know that speed is often tied to some kind of negotation-game what you are willing to give me ;-) And I am aware that many of the numbers are not the absolute truth, depending on many variables. I tried, as good as I can, to include this awareness in the way I phrased the questionnaire. I could have done better most probably.
As I tried to explain in my original posting, I just try to grab a collection of data that helps trainees starting out to get a feeling of what different aircraft types are roughly capable of doing. They do, of course, get complimentary explanation to the numbers, like possible limiting factors and how different circumstances can affect performance limits. I do this completely unsalaried in my free time, just because I really see the trainees struggle a lot on simulator training with these kind of things. The environment is different than in real life: the simulator pilots cannot retrieve actual possible speeds from the system, as there is no computer that calculates green dot speed or other performance numbers for each aircraft. It's an ATC simulator ;-) I would really like to support them by giving them a table containing a visually compelling comparison of performance data of different aircraft types with color scales (green - orange - red) that indicate that some speeds might not be possible under some circumstances. In order to better understand, I wanted to attached I screenshot from what I got so far (which is not a lot and not everything confirmed, unfortunately). Unfortunately that is not possible with my little number of postings here.

[FlightDetent]

A320 series:

no go red: .81 and more
yellow: .80
green: .79
gold: .78-77-76
green: .75-74
yellow: 73-70
red no go: .69 or less

The gold range and the (s)lower color range would be .1 maybe .2 different among 321-320-319 and possibly the NEO versions. The colour coding is tailored per your explanation to show viability for ATC purpouses.

Hope it helps, you're welcome to to ask further

[twhizzle]

Yes, that helps a lot, thank you. Do you know how the NEO versions differ from the classic ones, in performance/speed regard? Or is it more or less the same?

[FlightDetent]

They should be identical, the wing and rest of the airframe are the same save a few tweaks. The efficiency of the engine (low fuel burn) and lease rates on new toys (redhot high) would traditionally suggest a faster speed schedule to reach the optimum cost equilibrium. Yet there is a long list of reasons which could topple that logic completely upside down. I do not have any relevant personal experience.

To re-iterate, the gold range always sits inside the green band. The gold band is the pilot's preferred choice in accordance with airline policies. Those may as well require different speeds every now and then, but it is impossible to systematically predict when the need comes. NEO or not.

edit: The CLIMB performance is significantly better although there have been some administrative thrust limitations since the engines are designed very delicate and not all the hardware is yet optimized.

[twhizzle]

Oh, sorry! I have somehow missed your answer.
Thank you very much for the additional information. As far as I have found out in the meantime, the technical performance differences betweeen ceo and neo should be negligible, just as you say. I have had a few of the neos at work recently and couldn't make out much of a difference myself.