Power/Pitch controls Speed/ROD?

[Brian Abraham]

We had a discussion recently in another thread on this perennial subject so was intrigued to come across these notes on a 737 Landing Technique web site. Coming from a rotorhead background, and given the previous thread on the subject, I'm intrigued as to why the rationale might change pre/post glideslope capture.

During intermediate approach - before glideslope capture
Speed is controlled by pitch
Rate of descent is controlled by thrust

During final approach - after glideslope capture
Speed is controlled by thrust
Rate of descent is controlled by pitch

Let the fight begin.

[Milt]

So you want to fly by numbers!!

Why not just use your controls as YOU wish to make the machine do your bidding. It should be instinctive.

[Capt Fathom]

The above statements are referring to Autoflight Modes.

If you are on descent, the aircraft pitches to the set speed, and the thrust governs the Rate of Descent.

When you get Altitude Hold, it reverses! The aircraft pitches for the rate of descent(zero) and thrust governs the Set Speed. Same when the Glidepath is captured!

[The Bunglerat]

In simple terms: Whereas an enroute climb or descent profile can be parabolic, once established on glideslope the aircraft is required to maintain a fixed path (i.e. a linear 3 degree profile). Thus, any attempt to bleed off excess speed for example, by pulling back on the stick to raise the nose, will obviously result in the aircraft deviating from that path. Therefore, it is necessary to use the elevator for pitch and attitude control only, thrust levers to control speed.

I'm sure others can provide a more technical explanation, but it works for me.

[tinpis]

Christ almighty not this again

As Milt sez if you have to THINK about what youre doing maybe youre in the wrong line of work?
I wouldnt expect (except in Pommyland with 200 hour wonders) you would have to ponder this crap by the time you are turned loose on a 737.


*mutter ...mutter...WTF they turning out these days?*

[Feather #3]

Blimey...can someone publish a thesis on this which the Woomeri can simply insert when this crops up every 6 months or so?

G'day & Merry Xmas

[tinpis]

I ve taken me pills.

Merry bloody Xmas

[Pinky the pilot]

I've taken me pills

Tinny me old..You would'nt be like the character to whom my late Father (God rest his soul) used to refer.........Two pills and a tot of Whisky twice a day!
He was three months behind in the pills and five years ahead with the whisky!!

You only live twice. Once when
you're born. Once when
you've looked death in the face.

[DeBurcs]

3 words, 2 symbols

POWER + ATTITUDE = PERFORMANCE.





Has anyone heard of that really funny list of maint log snags by pilots and the even funnier replies by mechanics???

[Brian Abraham]

SORRY I ASKED I thought I may have been talking to adults.

Capt Fathom,
Thanks for being the only intelligent life form out there.

[Dry_Twotter]

The above statements about pitch and power are true for MOST a/c, except for one:

The C207

Increase Power = not much happens
Decrease Power = alot happens e.g. 2000fpm decents
Push nose down = " " " " "
Pull nose up = suicide!

[eagle 86]

Brian,
Not being an expert on F/W auto pilot systems ie are they true four axis systems but based on some experience with three axis helo systems then it appears to me at the point of G/S capture the pilot has set a power to achieve some where around the correct ROD and then the helo pitches to fine tune this ROD and hold GS. I know when I hand fly an ILS I endeavour to use power for ROD/GS and pitch for IAS - ie the way I was taught to fly P+A=P.
If you recall your Wessex days this helo had, although crude, close to a true four axis autopilot - remember the trepidation with which you engaged RADALT height hold when you reached jump height and the frequent overtorques as the system hauled in hover power in the South China sea at night.
I too wonder why you have raised this subject again in another form - Christmas is supposed to be a time of peace!
GAGS E86

[Brian Abraham]

E86,
Just making sure the gag reflex is up to snuff before they hook into the Holiday dinner. (not allowed to call it Xmas in these PC days I'm told)
A Festive Season to all

[eagle 86]

Brian,
Crap I'm a fcuking Christian and so it is fcuking CHRISTMAS - be careful you are supporting the limp-dick, trendy lefties who are selling our world down the gurgler in the name of this PC bull**** - be warned - don't pander to them!!
E86

[Captain Sand Dune]

Indeed..............

A happy Christmas to all!!

[flyforfun]

DeBurcs

I think this may be it:

P: Left inside main tire almost needs replacement.
S: Almost replaced left inside main tire.

P: Test flight OK, except auto-land very rough.
S: Auto-land not installed on this aircraft.

P: Something loose in cockpit.
S: Something tightened in cockpit.

P: Dead bugs on windshield.
S: Live bugs on back-order.

P: Autopilot in altitude-hold mode produces a 200 feet per minute descent.
S: Cannot reproduce problem on ground.

P: Evidence of leak on right main landing gear.
S: Evidence removed.

P: DME volume unbelievably loud.
S: DME volume set to more believable level.

P: Friction locks cause throttle levers to stick.
S: That's what they're for.

P: IFF inoperative.
S: IFF always inoperative in OFF mode.

P: Suspected crack in windshield.
S: Suspect you're right.

P: Number 3 engine missing.
S: Engine found on right wing after brief search.

P: Aircraft handles funny.
S: Aircraft warned to straighten up, fly right, and be serious.

P: Target radar hums.
S: Reprogrammed target radar with lyrics.

P: Mouse in cockpit.
S: Cat installed.

P. Noise coming from under instrument panel. Sounds like a midget pounding on something with a hammer.
S: Took hammer away from midget

FFF

[Brian Abraham]

E86,
You have my vote in spades. PC is some thing I've never been called. Mind you I've been called a lot of other things.