When can you call "Positive rate!"?
 

I'm practising go-around procedures and need to call "Positive rate" when it is positive. But when can you say that? I give you 3 options here to make it easier.

1. V/S (Vertical speed indicator) shows over 0 fpm. (Ex: +50 fpm)
2. V/S is moving upward to 0 fpm. (Ex: -200 fpm, the needle continues moving up.)
3. Altimeter is increasing. (Ex: 300 ft -> 320 ft)

There are points to discuss.

1-a. For small aeroplanes, they can't actually climb when the gear is down, so you have to retract it right after full power is applied, otherwise it will never climb in some conditions.

1-b. For big jets (multi-engine), even with one engine is inoperative, they are no problem with climbing. If you are close to the runway and going around, you may touch the ground and continue climbing, so it is not very late that retracting gear when you are pretty sure that you are climbing.

2. V/S is the most unreliable instrument and has a lot of lag. You can assume A/C is gaining the altitude when V/S is positively moving up.

3. Altimeter is more reliable than V/S.

Which option would you like to choose, 1, 2, 3 or other choice? Please let me know.

Thank you in advance.

"1-a. For small aeroplanes, they can't actually climb when the gear is down, so you have to retract it right after full power is applied, otherwise it will never climb in some conditions."

So how did the plane get off the runway so you could retract the gear? Or are we talking twins? There are some twins that won't climb even with the gear up on one engine. Just prolongs the agony.

Personally I use the altimeter.

I would bugger off #2.

A change from a negative rate to a lesser negative rate is NOT "positive rate".

A combination of #1 & #3. I'd want to see the VSI actually showing positive and the Alt start to show an increase.


Don't rely on just one indication. If you do, you are not looking at the whole picture.

For example, I've done plenty of takeoffs from runways where after liftoff the Alt is showing an increase but the VSI is showing a decrease yet i'm climbing away.
Why? Downslope on the runway... Takes a second or two for the VSI to get back up to "positive". Strange but true.

Positive sustained climb as indicated by the pressure altimeter.

Exactly!

On takeoff, you wait to hear all the ground-safety locks click before you look for corroborating instrument indications. That also helps the wait for dips in Altitude and/or V/S after rotation.

On go-around, there are no ground safety locks to worry about. Wait for 2 instruments (Altitude and V/S) to indicate climb. If over the runway, RadAlt is good, too.

B737 specifies altimeter.

A319 same Alt

Steady Altimeter increase. The word "Steady" added to avert any false illusions of climb as opposed to momentary small zoom climb due to over-rotation.

The Original poster alluded to the VSI (pre IVSI) being the most unreliable instrument due to time lag. That's actually a point in favour for the VSI, as, if it is now showing a climb, that climb has been in effect already for several seconds, again, a Sustained climb.

So, Steady Altimeter increase (albeit ever so slow) plus a steady VSI positive indication will jointly give a good assurance of positive climb (IVSI could also be subject to momentary small zoom climb due to over-rotation).

If you have it in your kit, add a sustained positive FPA/FPV indication to the confirmation process.

Regards,

Old Smokey

Personally, I like to use the Mark I eyeball. If the houses are getting smaller, we're climbing. I use to work for a little known airline, TWA, and the only call was "Gear Up". The pilot flying had to be aware. Of course, like everything, "trust but verify". BTW, this technique has worked for my 37 years of aviation. Another way to look at it, is if you have rotated, you are past V1 and then some with no other way to go but up. But for all the lawyers, it sounds good on tape. ;)

fwiw,

gumby

744 procedure:

Radalt and iVSI......

My outfit's SOPs specify that the PNF has to check both ALT and VSI before calling "positive rate".

Cheers :cool:

Call for Gear up
 

I just wonder how we managed to fly for so long with so little trouble.

When the PNF saw the Trend of the VSI or IVSI was up and the Altimeter Trend was up, the call was " Positive rate" and the Pilot flying woud call " Gear up". The PNF would call "Gear is up " when indicated.

Tmb

I remember being scoulded in the sim for calling positive rate.
Its positive climb apparently!

Anyway you should check vsi and rad alt.

In our outfit (A320/321/330) "Positive Climb" is a PNF call on checking positive V/S and increasing radio altimeter.

I also tend to check increasing baro alt as well, but rad alt is what is specified in the SOPs.

I´ve often wondered why the call is "positive rate of climb" ...why not just climbing or descending? A negative rate of climb seems silly to me.

KDY

An airline I was with 3 years ago went to the trouble of changing the call to 'positive climb' instead of 'positive rate'.