'Mustafagander', I agree, the RAD ALT on the 747 always reads -8 feet on the ground. This is the length of the 'truck'. On landing, 'heel' first (unlike the 767 which is toe first) the RAD ALT indicates 'zero' and -8 feet once the whole lot is in contact. Very accurate. All this is abit technical, there are many obvious clues that one is going 'up', including the loud gear relay switches. I agree you need two sources and need to have it correct in the manual, but isn't it sad everything including the bleeding obvious has to be a SOP.

If you're not sure whether the a/c has a positive rate, or not.....

Perhaps you ought to give up flying and take up something less challenging. Knitting maybe.

I realise that they have to write a rule for everything these days (and for the record, where I work you are supposed to wait til the climb shows on the altimeter).

What happened to airmanship?

Hi eagle737,

There are lots of suggestions there and most point to having at least two sources indicate a climb.

In the simulator with an engine failure on take off, I've seen some excited crews call "+ve climb" when we are about 5 feet radio, and the aircraft is hardly climbing yet. The open gear doors create more drag initially, and some crews may fly level for a while or even sink a little.

So the "+ve climb" call needs to be made after being certain the aircraft is safely climbing away from the runway, and not just an automatic call having seen one instrument twitch. The day you have a real engine failure on take off is the one time you don't want to make that call too early.

Take into account runway slope. You can have positive ROC with the wheels still on the ground!

I like the latter part. Might not work for the A343 though, too subtle...

when you lose sight of the muppets:}

I'm with BarbiesFriend. If you cant work out if the aircraft has left the ground then you need to find another job. It aint difficult!!!!!!

Blimey, how complicated do we want this to be? I'm with barbiesfriend and qwerty. When the big needle on that clock like altimeter thingy is moving clockwise and the VSI needle has got a slight upward pointy angle?

VSI indicating climb, altimeter increasing, radalt increasing and beyond 20'?

If you want ball park guidance, keeping it practical and it's not further clarified in SOPs and it's 125m visibility in complete overcast then how about that then?

Very true for some light twins.

But the question was asked initially for the B737? In this case, there in no real gear doors. Even none on the main gear. Concerning the nose gear, they are already open when the gear is down.

Hi Kag,

I don't know what you operate, but most of my previous types have large doors which open to let the gear transit, then close around the extended gear. Hence 3 limiting speeds with the gear: 1) Extended, 2) Lowering, 3) Raising.

What's yours?

Eagle737


The 737 FCTM used to read “positive rate on the IVSI and Altimeter”

I believe that due to the sensitivity of the Instantaneous VSI this requirement was removed.
Using only the Altimeter, with its pressure lag, is a more conservative indication of positive rate. Particularly in a windshear encounter.
In a two crew aircraft both pilots are confirming positive rate before gear retraction giving redundancy.
“Positive rate” (Altimeter increasing) for gear retraction is therefore the same for Take Off or a Go Around.

The IVSI, RA, Ground flight relay, Attitude and external visual indications are all useful for your situational awareness, however all have limitations.

That one: (sroll down).

I agree with your post, just one thing (again) "positive rate" refers to the VSI, "positive climb" to the altimeter.
The VSI gives a rate (positive or not), the altimeter a climb or a descent.
I know this is a detail, please don' t be offended.

Hi Kag,

Sorry - I'd lost the initial thread of B737 - with contributions from B777, B747 etc. Thanks for the reminder that B737 doesn't have gear doors that close around the extended gear - I'd forgotten that.

If the houses, trees ,Moose are getting smaller, your going up, if the Moose is running like hell, houses ,trees getting bigger, your going down, works every time!

I am with a few of you here.....is this a serious question? Is this really worth the bandwidth?

This is an old conceptual problem which come from the begining of our careers.When you are at the flying school , since the GA airplanes have no RA , you are teached to check the V/S.Then you go to the medium jets and you continue using the V/S isntintively for all your life until the question arises.

In the medium jets , this is not a big deal since they are still short, but you can already note some erros ,despite V/S information is beeing provided by IRS.

When you go to the large jets, since the moment that you start rotating until the point you get your wheels flying take some time. It hapened to me srveral times , to hear from inexperienced pilots "posite climb" with the MLG still on the runway.

I take a look at the V/S , but the reference I really consider is RA.

+ve rate of climb
 

two things which can help you determine +ve rate of climb...

1. listen to click noise of landing gear solenoid, which indicates that a/c has gone from ground mode to air mode.

2. movement of altimeter reading on the positive side.

3. IVSI a big NO.

hope it helps........

If you had decided that IVSI +500 fpm would heed the call; is that still NO for IVSI or rather sensible use of the most precise instrument available?

All under the condition that you need/have to pronounce a "numeric" definiton of positive veritcal. As long as you are happy with the "gut feelin'" description all is well even with Mk1 eyeball/ears. Some actually need to standardize beyond such definiton.

FD (the un-real)

positive climb
 

am adding another aspect apart from takeoff sit. what is considered as positive climb during upset recoveries / stall rec for getting gear up ?