Use of V/S in RVSM

[b.anakin]

Our Part A tells me that only FLCH (LVL CHG) or VNAV are approved for use in RVSM airspace and that the "use of other modes could introduce further hazards, and therefore be undesireable"

Now this slightly makes sense with the 75/767s, 'cos V/S doesn't have speed protection, but it doesn't make much sense on the 737, which does.

There is also a reference to an AIC 80/2000, which doesn't seem to exist anymore.

Can anyone help me out with this? And does anyone have a newer reference for the AIC?

Many thanks.

[Willit Run]

lets see, most of the world is now RVSM, so we should not use V/S to climb or decend?

Folks, were paid to be able to climb and decend a plane at certain speeds, thats what we trained for. Thats basic 101 flying!

sorry if i offended anyone!

[BEagle]

Just make sure that you've got less than 1000 ft/min when 1000 ft to go to the new level and things should be fine.

I used to teach it as "1000/1000" - the idea being to prevent some TCAS alert for someone else.

[b.anakin]

Yep, all good stuff, perhaps I should be more specific.......

1. If you want to reduce your r.o.c to 1000fpm, what's wrong with using v/s? It seems like a perfectly appropriate mode to use.

2. What does the man who writes this in my Part A know that I don't?

3. If you don't use v/s, you'll need to reduce thrust or increase speed, both a little fiddly and somewhat suboptimal.

4. If anyone has a copy of AIC 80/2000, I'd be glad to see it.

Ta.

b.a

[cooldaddy]

At least 500ft/min so as the other guy can instantly see if your climbing/decending

[A330AV8R]

At least 500ft/min so as the other guy can instantly see if your climbing/decending ????

ummm

If your in cruise within RVSM wouldn't you first and foremost REQUEST ATC to give you another level due to whatever reason ?

If your in climb or descent don't you stick to a speed schedule ?

or is it just me ?

[gimpgimp]

737 NG Ops: My airline does not recommend VS for high alt level changes. Incidents have occurred where sharp wind changes have resulted in the 15 kt below low speed trigger and reversions to LVL CHG where the aircraft has pitched down to recover so much that the resulting descent rate took the aircraft straight down tru' the level just vacated. Lvl Chg or VNAV mode is safer.

[b.anakin]

gimpgimp,

Thanks for that, another piece of the jigsaw....... Nice to see it's not just the Aussie bowlers that are being helpful this morning. (sorry mate, couldn't resist that)

Out of interest though, what do you do, sop or otherwise to reduce your rate of climb/descent when approaching your level if you're using vnav/lvl chg?

Cheers.

b.a

[Shaka Zulu]

Try LVL Change and instead of ECON 0.77 (I know most of you chums fly at .80 on the 737 anyway) try LVL CHange 0.80 when approaching lvl, keeps the ROC down but will ensure that you get there.
I just look at the ROC (approaching FL400) its normally less than 1500 fpm anyway, so leave it in VNAV.
and yes that pitch down recovery is not desireable i can tell from firsthand experience. it feels exciting for your pax down the back too!

[Intruder]

Our FHBs (742 and 744) recommend use of V/S. FLCH in the 744 may command 2000 FPM or more.

[Winston]

The answer to the original question is we should not use vertical speed as in that mode it is possible to fly AWAY from the selected altitude. VNAV and FLCH will ALWAYS fly towards the MCP alt.

[barit1]

BUT - isn't this what got those chaps in trouble going for FL410 last October 14 ?

[Intruder]

The answer to the original question is we should not use vertical speed as in that mode it is possible to fly AWAY from the selected altitude.

Using that logic, we should not use pilots, either!

AFAIK, the pilot still initiates climbs and descents by setting up the MCP, FMS, throttles, and other controls, then either hand-flies the airplane or monitors the autopilot. To disallow use of an automatic or semi-automatic function because it is not idiot-proof is patently ridiculous.