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JWMuller

Positive Rate Gear Up?

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Hello, I don't know when I say positive rate and when to put the gear up in airliners such as Boeing and Airbus, Ive tried searching online but with no luck. Could you explain it to me and when to say it and when to raise the Gear?

 

Thanks` :help:  :help:  :help:  :help: 

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Pretty straightforward really: check that a positive rate of climb is indicated on the VSI and the altimeter is also increasing. If you are being particularly belt and braces it is also not a bad idea to check that the radio altimeter is also increasing, giving you three separate indications that the aeroplane is in fact climbing away.

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Th

 

Pretty straightforward really: check that a positive rate of climb is indicated on the VSI and the altimeter is also increasing. If you are being particularly belt and braces it is also not a bad idea to check that the radio altimeter is also increasing, giving you three separate indications that the aeroplane is in fact climbing away.

thanks

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Normally, you'd have the Pilot Monitoring watch the instruments on the take off roll, and he/she will make the announcements regarding the take off roll and climb out, so that the Pilot Flying can keep his/her head up and fly the aeroplane (of course we, as simmers, either have to do that ourselves, or use some add-on to give us an AI co-pilot, which is of course handy as well as being more realistic, since many add-ons will let you have your virtual co-pilot raise the gear once a positive rate is achieved, for example Pro ATC X, MCE, Vox ATC, FS2Crew etc can do that, and you could do a lot worse than to use something like that).

 

So, you get your calls: 'airspeed alive', '80 knots' 'V1' 'rotate' 'V2' etc (the instrument crosscheck at 80 knots relates to the gear up call, since it is to ensure both pilots have the same readings on their ASIs etc, because on many aircraft, the left and right instruments feed off different pitot heads and static ports, that's particularly important, because the left instruments are usually the ones that send data to the transponder, so if it's broken or misreading, it will lead to cockpit confusion and, you'll be sending incorrect data to ATC's radar scopes, but also because the Pilot Flying would be well advised to glance at the Altimeter and confirm a positive rate before he calls for gear up, this is one of the many reasons whay a HUD is starting to show up on airliners).

 

Now, theoretically (and I do mean theoretically) you could raise the gear lever on an aircraft when it is on the ground and the downlocks would prevent it raising until there was no weight on the wheels, so it would raise the moment you lift off (this would be a dumb thing to do of course, but theoretically it would work on at least a few aircraft). The reason it would be silly to trust that mechanism and do that, is that when the gear raises on many aeroplanes, the movement of gear doors and rotation of the wheels sideways as they fold in, will increase drag quite a bit, and if you've only just lifted off, that increased drag might reduce your airspeed to a point where you'd sink back onto the runway. It's also worth bearing in mind that right after you've lifted off, and for quite a few moments before you gain significant height, you are in 'ground effect', where the air under the wings is being forced down, bouncing off the ground and coming back up at you to push you up, so low down you are riding on a cushion of increased updrafts, and if you fly up out of that at a low speed and are no longer in ground effect, you could actually start dropping back down, so having your gear up in those circumstances would not be a good thing.

 

This stuff is important to know and is also why you should not rely solely on the VSI to confirm a positive rate of climb, because it is an instantaneous indicator of movement; thus it might show a climb from merely hitting an undulation on the runway or from a gust lifting a wing a little bit on the take off roll, whereas seeing the Altimeter steadily going up over a couple of seconds is a much better indicator that you really are in a continuous positive rate of climb, and if you note that you are accelerating too, so much the better because that acceleration will increase lift as well.

 

So, with all that in mind, the Pilot Monitoring will make the announcement as to when there is a 'positive rate of climb', the Pilot Flying will then be able to advise the Pilot Monitoring to raise the gear by saying 'gear up'. This should always be the way it is done, because if something untoward occurs and the Pilot Flying decides to plonk the plane back down on th runway for some reason, you don't want the Pilot Monitoring simply popping that gear lever up the moment he/she says 'positive rate', so he/she waits for the Pilot Flying to say 'gear up' in order to confirm that the Pilot Flying is happy that the aircraft is climbing and accelerating and so wants the gear raised.

 

On airliners, that positive rate call will typically occur at 100-200 feet above the runway, with the gear hopefully up and stowed by the time it reaches 300-400 feet.

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Ouch. That's not going to polish out with a old rag and a bit of T-Cut lol :-)

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In my ops it's called by the Pilot flying and echoed by the pilot monitoring. This is how its flown in our SOPs.

As the PM calls "Rotate", we add back pressure and smoothly pitch 2 to 3 degrees per second up to target pitch(V2+10 OR V2+etc depending on airplane). As you approach target pitch, you add nose down trim to capture it. Once you capture it, look at Altimeter, VVI and Radar Altimeter. Once you confirm all three are increasing, you call "positive rate, gear up". The PM will confirm climb and echo "positive rate, gear up" as he/she selects the lever to up.

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Normally, you'd have the Pilot Monitoring watch the instruments on the take off roll, and he/she will make the announcements regarding the take off roll and climb out, so that the Pilot Flying can keep his/her head up and fly the aeroplane (of course we, as simmers, either have to do that ourselves, or use some add-on to give us an AI co-pilot, which is of course handy as well as being more realistic, since many add-ons will let you have your virtual co-pilot raise the gear once a positive rate is achieved, for example Pro ATC X, MCE, Vox ATC, FS2Crew etc can do that, and you could do a lot worse than to use something like that).

 

So, you get your calls: 'airspeed alive', '80 knots' 'V1' 'rotate' 'V2' etc (the instrument crosscheck at 80 knots relates to the gear up call, since it is to ensure both pilots have the same readings on their ASIs etc, because on many aircraft, the left and right instruments feed off different pitot heads and static ports, that's particularly important, because the left instruments are usually the ones that send data to the transponder, so if it's broken or misreading, it will lead to cockpit confusion and, you'll be sending incorrect data to ATC's radar scopes, but also because the Pilot Flying would be well advised to glance at the Altimeter and confirm a positive rate before he calls for gear up, this is one of the many reasons whay a HUD is starting to show up on airliners).

 

Now, theoretically (and I do mean theoretically) you could raise the gear lever on an aircraft when it is on the ground and the downlocks would prevent it raising until there was no weight on the wheels, so it would raise the moment you lift off (this would be a dumb thing to do of course, but theoretically it would work on at least a few aircraft). The reason it would be silly to trust that mechanism and do that, is that when the gear raises on many aeroplanes, the movement of gear doors and rotation of the wheels sideways as they fold in, will increase drag quite a bit, and if you've only just lifted off, that increased drag might reduce your airspeed to a point where you'd sink back onto the runway. It's also worth bearing in mind that right after you've lifted off, and for quite a few moments before you gain significant height, you are in 'ground effect', where the air under the wings is being forced down, bouncing off the ground and coming back up at you to push you up, so low down you are riding on a cushion of increased updrafts, and if you fly up out of that at a low speed and are no longer in ground effect, you could actually start dropping back down, so having your gear up in those circumstances would not be a good thing.

 

This stuff is important to know and is also why you should not rely solely on the VSI to confirm a positive rate of climb, because it is an instantaneous indicator of movement; thus it might show a climb from merely hitting an undulation on the runway or from a gust lifting a wing a little bit on the take off roll, whereas seeing the Altimeter steadily going up over a couple of seconds is a much better indicator that you really are in a continuous positive rate of climb, and if you note that you are accelerating too, so much the better because that acceleration will increase lift as well.

 

So, with all that in mind, the Pilot Monitoring will make the announcement as to when there is a 'positive rate of climb', the Pilot Flying will then be able to advise the Pilot Monitoring to raise the gear by saying 'gear up'. This should always be the way it is done, because if something untoward occurs and the Pilot Flying decides to plonk the plane back down on th runway for some reason, you don't want the Pilot Monitoring simply popping that gear lever up the moment he/she says 'positive rate', so he/she waits for the Pilot Flying to say 'gear up' in order to confirm that the Pilot Flying is happy that the aircraft is climbing and accelerating and so wants the gear raised.

 

On airliners, that positive rate call will typically occur at 100-200 feet above the runway, with the gear hopefully up and stowed by the time it reaches 300-400 feet.

Oh wow, Thanks for all the typing work. I have to say.... That is a lot of words!! :smile:  :smile:

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