Need some numbers about aircrafts performances...

[zesheriff]

Hi everybody.

I'm training ATCOs at Paris CDG airport (no comment about my "failure" in that, I'm not the only one doing it here :p), and as I'm trying to update the lesson on aircrafts performances, I'd like to have pilots feedback.

The problem is that the figures I can find are purely theoretical, with MTOW, N-1 engines, etc, whereas what I need are what happens daily : your don't always take off with MTOW and/or an engine failure, you have cost indexes to follow, some specific company procedures...

I know the IANS database, which is useful (Aircraft Performance Database V2.0 (http://elearning.ians.lu/aircraftperformance/)), I have my own experience, which helps too... But I'd like to have pilots feeds on this...

Could you for example provide me (with your type of aircraft of course :O), what you daily perform :

Departing aircraft :
- the runway length you need (and what's the minimum/maximum you may need if you are really light/heavy)
- average VR, average V2 (and what's the minimum/maximum etc)
- initial rate of climb for noise abattement procedure (ie 3000ft at CDG), then until 10,000ft, (and the maximum we could ask you if light/heavy)
- the speed you usually take to climb until FL200, with the rate of climb...

Arriving aircraft :
- rate of descent average/maximum with a speed of 250kts, 220kts, 200kts, 180 kts, even 160kts... (I know your minimum rate of descent, it's called "level"... :\)
- maximum speed to intercept a LLZ, a glide
- average minimum approach speed (and what's the minimum/maximum you may need if you are really light/heavy, if there is some crosswind, etc)
- average runway length needed...

And any other thing that you may think helpful...

Thank you to grant me some of your precious time, just think that we will have returns in a better atco service... (or at least we'll try ! :})

[Piltdown Man]

OK - I'll have a go:

Embraer 190

Going up:

TORA - 1,800m or more please. But only if we have performance figures available. The problem in our modern world is that we can't go flying unless the computer says "Yes" AND we have the figures for the intersection available - even if you offer us 3,000m we still might not be able to depart. VR = 130 - 145 Kts and V2+10 between 140 = 155 Kts. Initial rate of climb - 3-4,000 fpm which I why we don't like surprises like "Stop climb altitude 3,000 feet" when we pass 2,500'. Up to FL100 we'll be doing at least 2,500 fpm at 250 Kts and from there on 270 Kts with 2,000 fpm until FL200.

Going down:

250Kts will give about 1,800 fpm. At 200 Kts (Green dot - ish) this will reduce to about 1,100 fpm. The speedbrake is a pretty pointless device which can only be used when clean or Flaps 1 and above 180 kts. It will add only a few hundred feet per minute descent but shake the passengers more. At 160 kts, the ROD will increase again to 1,400 fpm due to the extra drag with flaps. I'd prefer not to intercept a LLZ with more than 220 kts but if you give me enough track miles I don't mind 250 kts. I don't want to intercept the glide with much more than 210 Kts or so otherwise I won't be able to slow up: I'd prefer slower. Minimum Approach speed 125 - 130 Kts. As for crosswind, the book says 38 kts but when the wind is that strong "Bitchin' Betty" gets very upset and starts screaming "Windshear! - windshear! - windshear!" so you get to go-around and eventually divert. LDR - If pushed, I'll take 900 m but 1,300 m would be better.

What do I really like from ATC? An idea of your plan. Tell me that I'm fifteen or so in traffic and that I have 55 track miles. If slowing up will be sensible, let me know and I'll save fuel. I also like unrestricted climbs and descents to stop the power levers from moving about. I also appreciate advance notice of being held at a level. Then we'll normally increase speed and zoom climb once you give us climb clearance, unless of course it doesn't make sense. I'll do the opposite on a descent and bleed speed off. Also, please tell us early which runway we'll be getting and if you want us to change late in the approach, allow a visual approach - typing low down is not a good idea.

What do I hate: Surprises!

PM

[barit1]

I also like unrestricted climbs and descents so stop the power levers moving about.

Airlines worldwide should appreciate this, because it minimizes thermal transients in the engines. This gives the potential for longer engine parts life, and better long-term fuel economy.

If an interrupted climb is required, provide advance notice so the thrust (and turbine temperature) can be reduced gradually.

[welliewanger]

Bombardier Global Express:

If we're light. No wind, 1013, 0 degrees:
TODR = 1111m (factored)
V1 = 88kts
Vr = 88kts
V2 = 111kts
Net climb gradient 10.85%
Rofc I guess 5-6,000 fpm
Climb speed = 300kts / M0.83.
Vref = 107
LDR = 1103m (factored)

Heavy aircraft. (MTOM or MLM) wet runway, anti ice on
TODR = 2437m (factored)
V1 = 119
Vr = 127
V2 = 139
Net climb gradient 10.05%
RofC estimate initially 2000 fpm accelerate to 3000 - 3500
Vref = 128
LDR = 1349m (factored)

As for alterations to approach speed, we'll rarely fly at more than Vref+10.

Pet hate: being told to go down AND slow down. You can have one or the other, not both! Unless we use speedbrake, and everyone know that speedbrakes kill fairies!

Max rate of descent (without speedbrake) = 1/2 speed + 200 fpm so at 250kts we'd descend at 1400fpm. With speed brake we can drop like a rock!
Max LLZ intercept. That depends on the angle. I've done 250kts easily from 30 degrees. But 160kts at 90 degrees is tricky.
Once on the glideslope, the only way to slow down is with more flap or speedbrake.

[zesheriff]

Thanks for these answers... :ok:

Do we have only Embraer and Bombardier pilots on this forums, or are the other ones just to busy in august... ? :suspect: