VNAP Procedures

[TAAMGuy]

Hi Folks.

I'm working on a project involving noise abatement departures. Could someone please tell me a representative V2 speed for A320, B737-700, and maybe CRJ2?

Also, can someone define Vzf for me and tell me what that speed might be on a representative day for the above types? Let's assume sea level for all. Thanks much.

[Mr Trim]

For the B737-700 I think you could use a V2 of 135 KIAS as a mean value. For the Vzf you could use a speed of 200 KIAS, although I´m not as sure with this one. Regards.

[BOAC]

I'd go a bit higher for V2, say 145-150. 200 good for Vzf (min clean speed with a ?1.3g? buffer)

[Mr Trim]

Indeed, you could use a higher V2 value as BOAC suggests. My number was based on a mean TOW of 60t, with Flaps 5, which normaly renders a V2 of 135 (TOW - 25). Using Flaps 1 for take-off will raise the V2 value.

[Denti]

Depends on the procedures of the airlines, the available runway length etc. You can comfortably use a V2 range between 120 and 175 for a 737-700. After all you can use flaps 1, 5, 15, 25 for takeoff with thrust settings between 18 and 24k lbs, and you can of course use improved climb V2s as well which would shift them to the higher end of said range.

Designing departure procedures you have to cater for the highest possible speed or restrict speeds, otherwise you will have a turn radius problem. Lowest speed restriction i've seen so far was 190ktias, however i'm quite sure there are lower ones out there as i have seen mainly european airports so far.

[TAAMGuy]

Thank you gents. Climbing at V2 + 20kts would result in what kind of climb rate in fpm?

[mathy]

try this

Do you mind if I simplify this somewhat? Mr Trip suggests 60 tonne takeoff weight and for a still air ISA day at sea level V2 = 135 is probably the laptop answer. (That corresponds to about 11 tonnes fuel, 11 tonnes payload and 1600nm trip with "typical" reserves by the way). You should be able to climb say to FL370 in 115nm in just under 20 mins with adequate instaneous climbing reserves. Probably thus: 250kcas below 10,000, 290kcas above 10,000 until 29,500ft where speed becomes M0.76 all the way to 37,000ft. Say 2,900fpm to 1500ft, 3,900fpm thereafter to 10,000ft then falling to 1,300fpm at about 29500ft where 290kcas and M0.76 are identical. From there a steady reduction to 900fpm until nicely settled at 37,000ft and accelerated to M0.78 cruise. There are a lot of assumptions there and not a lot of good engineering grammar but I hope as a guide it isn't way too out for what you want. If you accept this then the formula for time increments "T" is:

T = [(h2-h1)]/[(RoC2 - RoC1)] * natural logarithm[(RoC2 - Roc1)]

If you are going to go into much deeper detail you probably need someone with a BLT (no, that is a Boeing Laptop Tool and not a sandwich) who is prepared to do a bit of tapping. Otherwise the maths can get very tiresome though not unduly awkward with a spreadsheet.

Any help?

[TAAMGuy]

Quite helpful; thank you.

My little study involves building simulations of the two noise abatement profiles commonly used here in Canada. I will then quantify how these profiles, flown by a traffic sample of departures, (number, and type variable) impact time in queue, time in position etc. I will then compare one scenario (base case) to the other (option case) and quantify a delta. This becomes a decision support tool for those who contemplate and then implement change.

[BOAC]

Just bear in mind 60T is a bit 'light' for the 700. Used to 70T=long days

[Denti]

Depends on route network i guess. Quite used to a lot less than 60t as we use the 700 more for real shorthaul stuff (35 to 60 minutes sectors) and thin routes with loadfactors between 70 and 130 pax. But yes, there are some rare 5 hour sectors in there, but even then 70t is more common on the 800 on those.

[cossack]

TAAMGuy
As someone who works a lot of departures in a shift, maybe 15-25% use the VNAP-A profile. Some don't use it for noise purposes, but as a means to get to noise termination altitude quicker hoping for an earlier turn on course. AC seem to use the A when departing in the opposite direction of destination and the B the rest of the time, with a few exceptions. This turn on course sometimes does not come any earlier due to preceding traffic on the same route which they need to be spaced with.

The tower is required to give traffic to departure 3 miles in trail and the extra time spacing required to achieve this when an A departure is followed by a B is in the order of 15 seconds. On a runway which has 40+ departures an hour and maybe 6-10 of them are A departures, the extra time spent waiting could be as much as 2.5 minutes per hour. In reality this doesn't happen: we use mixed mode some of the time, so the A departure profile is a non-issue; there are types which are turned and therefore another non-issue; and we seldom have constant demand.

There are times, however, when the integration of A departures at YYZ does cause delays to mount. I'm thinking of departures from 33R when 33L is the landing runway. In this scenario there is a headwind exceeding 25kts on the surface (otherwise we wouldn't be using this operation) and usually a stronger wind aloft. Because of the reduced airspeed on the A departure and the increased headwind, ground speed is so low that the time spacing needed to achieve 3 miles in trail is much increased: I would estimate that it could be closer to 20-25 seconds extra. Some of this extra time can be filled with traffic that is eligible for turning and/or runway crossings (which we have many of in this configuration) but delays are caused without a doubt.

I, and i suspect most of my colleagues, would much prefer that all aircraft fly the same (preferably B) profile all of the time. Heavy types can fly the A without much impact on operations as spacing behind them is increased anyway and their airspeed on climb, even using the A, is greater than say a lightly loaded A319.

Maybe rather than trying to find a "decision support tool" we should do more to explain to those who use the A for "selfish" reasons, that their decision actually costs more for traffic behind than it benefits the few aircraft that use it?

DC

[BOAC]

If we are talking 'noise', the programme should really look at the worst case scenario rates of climb etc, should it not - ie max tow?

[mathy]

heavier effort

Just to check, the usual web reference is:

http://www.boeing.com/commercial/airports/acaps/737.pdf provided that no-one gives absolute verity to the info for real operations. It is very much a distillation for civil engineers but better than a poke in the eye with a sharp stick.

Despite the Boeing disclaimer in the above document I took a 150nm alternate, 30min hold, 6% reserves and no go around because that seemed to give the best match between my laptop and the Boeing -700 performance graph.

From the laptop long range cruise at FL360 is M0.774 and the climb schedule I took was 250/295/M0.75 with the crossover circa 28,000ft.

Distance in still air ISA is 2,100nm with 1,1670kg fuel of which 1,150kg is diversion, 1,150kg hold and 700kg for a nifty descent. This basically matches up to BOAC’s wish for a 70 tonne aircraft at brake release.

Then I hit <GO> on the BLT and it came up with 137nm climb in 21 minutes along with a lot of other stuff which I simplified. For example at the 1,500ft and 10,000ft acceleration points I took a round average of speed and tidied up the RoC figures. Using the formula for time increments given in my earlier answer I created this table, which is close enough I think. Therefore I hope this is helpful in trying to imagine where that 737-700 goes in terms of elevation, time and distance.

Elev ft RoC Time Inc GS Dist
AMSL fpm mins kts nm
35 2400 0 153 0.00
1500 2800 0.56 206 1.68
10000 2700 3.09 314 13.39
28000 1300 9.4 446 59.53
36000 600 8.84 430 64.53
Total 21.89 mins Total 139.13 nm

[BOAC]

mathy - the OP will only need rate to 3000' at V2+20 for noise abate. The rest of the 'noise' is 'someone else's problem'

[A321COBI]

BOAC - the rest of the noise is the passengers problem and very soon there are going to have to be major adjustments on aircraft as the aviation authorities come down hard on noise levels in the cabin

[TAAMGuy]

Thanks to all contributing. Could anyone offer V2 and Vzf for representative flights of the following:

B737NG short haul
B737NG long haul
A319 short haul
A321 long haul
B767
HS125
CL64
G4

Any and all data greatly appreciated.