Positive Rate, Gear Up, Flap Up??

[Big Kev]

Just noticed in one of my flying vids and from what an instructor said that I should do once is to confirm a positive rate of climb before retracting gear.

So I would assume that the aeroplane will always be positively climbing after take off so why confirm a positive rate of climb before retracting gear??

What if you don't have a positive rate of climb? - leave the gear down and prepare for a landing.

It just seems counter intuitive that after take off we confirm a positive ROC before retracting gear when we have just pulled back on the control column to raise the nose and commence a climb.

Mind you, confirming a positive rate of climb might have nothing to do with raising gear and might exist to combat the effect of the somatagraphic illusion that has caught a few people out at night but I'm pretty sure it is a check linked to raising the gear and must be done before doing it.

Could someone with retractable gear experience using these procedures please explain further.........


Thanks very much.......


:)

[Cloud Cutter]

When you're flying a large swept wing aircraft, it is difficult to tell when the main wheels leave the ground, using the VSI to confirm a positive rate of climb is good practice. However I do agree with you that in a light twin or turboprop it is pretty safe to say you should know when you're airborne, and you won't find the 'positive rate' call in many of these company's SOP. What you may find is a statement along the lines of 'call for gear up once a positive rate of climb is established'. This covers the possibility of wind-shear shortly after liftoff which may in the extreme case cause a sink back onto the runway.

[chief wiggum]

just a good practice to get into for when you have to do it single engine off a missed approach. Sometimes the inertia of the aircraft means that it will continue to sink, even after the power has been applied, and the nose raised. By confirming that you ARE climbing every time, then this won't lead to a ground strike. Also, it IS a good way to check that you HAVE actually applied power!
Another example of this would be a heavy jet executing a missed approach off an ILS. Quite often, the wheels will actually touch the ground in the go-around phase. Positive rate may not be achieved till quite a few seconds after applying TOGA power.

[Capt Claret]

And, in many aircraft types drag increases during the gear retractioin cycle due to doors opening. So, if the "this looks kool" method of raising the undercarriage is used, whereby the gear is selected up as soon as it is perceived that the aircraft has left the ground, and the rotation hasn't been all that effective, the aircraft could settle back onto the ground, sans wheels. :eek:

[Defenestrator]

Exactly Claret. That's why I reference 'positive rate' to the altimeter. Not instantaneous like the VSI or indeed an EVSI, but it registers positive indications of the climb and for mine is a much safer indication of climb during the T/O phase and a markedly less chance of resettling to the runway.
D:ok:

[3 Holer]

Correct Capt Claret and if you sustain an engine failure (multi-engined aircraft) after V1, you may not meet 1st segment requirements.

[scroogee]

Adding also that in some light aircraft the retraction cycle actually causes the gear to transition through an arc that is below the down and locked position. From memory the Cessna series were good for about 1 foot- could be spectacular for Ace-Hotshot.

edit to add: and in the majestic C337 if the rear engine failed and you selected gear up a ROD would result- not the best during a takeoff. If it was the front engine you should still have a ROC, but that was where the hydraulic pump was- so it was best to not fiddle with that bit.

[Tinpis2]

Hey Giant Kev wheres your brains :eek:

Could this not be a reason for simple aerodynamics:}

If we dont have a positive rate but are flying close to ground level and we retract flaps and gear what happens ?????

We get sink and hit the ground.

therefore;

positive rate, gear up, flap up

dahhhhhhhhhhhhhhh:} :E :eek:

[Lord Snot]

The best way to do the "kool" gear retraction without treading on ya dick is to hold it on the runway a little bit longer than usual, then select Gear Up.

Later, when the seat of ya pantz tells you the time is right, lift it off the deck.

The micro-switch, which never ever fails, will keep the gear down until you begin to lift off, whereupon it will initiate what looks like a snappy, pro-feshunull gear retraction as your mains are still leaving the ground. Chicks dig it!

Only you will know you were well above flying speed and well out of danger! Choice bro!! :ok:




Disclaimer: I do not recommend this practice and do not think it is funny. All slaggings will be ignored.

[ITCZ]

Tinpis, go easy on him -- he is asking a question. Better to ask a "dumb" question than to make a dumb mistake.

I assume that Big Kev is not talking about a commuter or transport category aeroplane, but something like a Baron/Navajo/C402.

So I would assume that the aeroplane will always be positively climbing after take off so why confirm a positive rate of climb before retracting gear??

They normally do climb after you haul back on the prong, yes. But not always. Thats one of the reasons why companies are forced to put up with trained pilots on their payroll!

Palm 90 pushed the levers forward and pulled back on the stick, but ended up in the Potomac River. That Canadian F28 at Dryden set full power for real, and when they pulled back on the stick, they ended up in the trees.

Wasn't supposed to, but there you are and here we are! Only part of the salary is for when things are going allright. The major part is for when things DON'T go to plan ;)

Hence PUFF checks, line up checks, EFATO briefs.... and the twin pilots mantra mixture up, pitch up, power up, dead leg dead engine, confirm with throttle, clean up, bank five to the live, half ball slip.... or whatever your instructor/chief pilot/handbook tells you.

Taking it back to the realm of the light twin, there is perhaps another consideration before pulling the gear up after takeoff.

Runway remaining, or the option to land ahead.

SOP in the C402 operator I worked for was not a "Vee One Rotate!" situation. More like a check full power, monitor acceleration via a rule of thumb (three quarters VTOSS by 500m of TO run or similar) lift off at 80 potatoes, accelerate to blue line and then if positive rate of climb and insufficient runway/clearway ahead for an emergency re-land, gear up.

The details are a little hazy now, but I do remember that it was drilled into us that there was little to lose and a hell of a lot to gain if the rubber was still down and locked in the first fifty to hundred feet if a nice smooth area was ahead of the nose.

[Sunfish]

It was interesting when I did my first unplanned go around in an arrow. Instructor hadn't yet mentioned pitch up, power up,positive rate, gear up flaps up. So naturally I just booted in throttle and the engine made this funny groaning noise......

[Di_Vosh]

Sunfish,

Mate, if that wasn't a wind-up, you may want to change instructors. :ouch:

DIVOSH!

[Lord Snot]

Maybe the groaning you heard was the gear warning horn when you sucked the gear up with full flap still selected..... :rolleyes:

[Capt Fathom]

Maybe the groaning noise was from the instructor as you booted in the throttle ! :E

[Sunfish]

The instructor noise was rather shrill as I recall, everything was sorted out in an instant. At least the Arrow had that bloody "automatic extend" feature disabled.

[wateroff]

Kev,

The question is to live or die.

"Insufficient runway or Clearway-Gear Up" unless there is 3k of runway then common sense prevails.

You will hear people preach about Decision "Speed" which is all good and well, but consider the option of a Decision "POINT" in space along the runway, where it would be a better option to continue rather than close the taps and crash into the trees ahead, just because you havent reached the infamous 'blueline'.

So,

'My decision to GO is based on insufficient runway or clearway where I will select gear up and GO"

This keeps it simple. Also know your drills in your sleep.

[Will Robinson]

I don't know how many other transport cat aircraft have this system, but in the Brasilia (and i think the bandit as well) there is a little red button next to the gear handle.When this is pressed it allows the gear to be retracted even if on the ground as the micros only stop the gear handle from moving on the ground. The purpose of the button is to allow an over ride incase the gear wont retract in a critical situation. The is a picture on the net of a Bras sitting on its tail aparently after the check captain pressed that button to prove to the captain that he was right about the micros stoping retraction on the ground:\

[Ex FSO GRIFFO]

Kev,
I remember a Be58 Baron crashed just after T/O on a DARK NIGHT whilst using the strip which pointed AWAY from town in NW Country WA, and thus had NIL reference lights, NIL horizon (outside), and apparently the pilot had NOT established his positive rate of climb, attitude, altitude increase, and, as the gear was retracted, possibly the pilot 'relaxed' his back pressure on the control column.
The noise of the acft ploughing through the scrub - for no apparent reason to the pilot - was probably VERY disturbing.
By day, I usually wait until I am 'visually' climbing OK, and, the remaining 'rapidly shortening' runway in front of me is of no further use to me, then 'Gear Up'.
By night, until I am 'instrumentally' climbing OK, then, the same will do thanks.
Hope this helps.:ok:

[Capt Claret]

When "Gear up" is called and it is my belief that we're in Kool mode, I find it takes me quite some time to lean over and move the lever. :8

[podbreak]

Its essential that you confirm you have a positive rate post rotation before you retract gear for reasons different to those retracting flap. You may well get the impression you've rotated when infact you have just enough lift through ground effect to bump you up. Problems may not be apparent until you've left ground effect, and the call is to simply confirm that you have positive lift out of ground effect, before you retract your gear. In smaller GA aircraft the takeoff may still be aborted when you realise that you have a problem at this point.

[TurboOtter]

Along with some of the other good reasons up there, I belive the main reason of confirming positive rate of climb is to ensure that you are in fact climbing, there are many reasons may have you thinking you are climbing, for example, surrounding terrian might give you false indications, a big one that most people forget is at night you might even feel you are climbing , yet you may even be decending.
Another point, what if you are incorrectly loaded, you pull back on the stick, assume that you flying, yet you are still trundling down the runway.

There are more reasons, but hey how many do you need to realise that it is an important call.

[Mr Garrison]

Hey Kev,

Turbo Otter presents a good reason. The somatagraphic illusion that is presented to pilots at night when climbing away into a dark area with no backlights can give the false impression to pilots that the aeroplane is climbing too much so a pilots natural response is to nose down slightly, but he/she does so without realising that by doing that, the plane is now flying straight and level or possibly in a descent, hence the reason why its vital to confirm a positive rate of climb.

The practice is followed over into the daytime primarily for the reason of confirmation of climb. Horizontal or vertical windshear can be a problem from nearby microbursts or thunderstorms hence its important to double check your climbing before raising the gear so you don't settle back onto runway on the aircraft's belly.

I normally confirm gear up at about 200' no matter what the runway length because by the time the gear has retracted, you would be at say 300' - 400'.
If you suffered at engine failure at this point then there would still be adequate time to lower the gear to land back on the runway or possibly some paddock/road ahead.......if its water or dense forest - then maybe best to not even lower the gear at all........


hope that helps.....

Mr G

:ok: