Climb power

[Guest]

I can't seem to get the climb power to work. I set up the FMC, turn on A/T, press climb then N1 the aircraft keeps accelorating right past V2+15 and keeps on going. Does anyone know what I'm doing wrong? I thought that N1 was suppose to hold V2+15.

[marcom]

The N1 mode will tell the A/T to set the max N1 that is selected on the TRP (Thrust rating panel). It won't adhere to speed restrictions, except for max operating speed, flap placard speeds and gear speeds.What you want is the takeoff mode, which you can only activate on the ground (by activating the Flight Director) and is only a flight director mode, meaning that this mode is not available to the autopilot. You can however activate VNAV (only available if you have a valid flightplan with all necessary INIT REF data filled out). This will then fly a standard climb profile but won't stick to V2+15.RegardsMark

[Guest wkzzo]

You need another vertical mode armed, such as vnav, flch or v/s. I usually arm Lnav and Vnav prior to takeoff and the flight director will transition to these modes after TO.

[Guest Mark McG]

Set V2+15, along with an initial first segment climb altitude in the VNAV climb page of the FMC as a speed restriction.eg.V2+15/1500ft or V2+15/3000ft.Arm VNAV on the ground.Aircraft will adhere to V2+15 for the first segment climb.Passing the speed restriction altitude, select the Thrust rating from the TMC, CLB, CLB1 or CLB2.Clean up the flaps as you accelerate to 250 knots.Do Not set the MCP Altitude as your VNAV altitude restrcition. Set this to the initial level off altitude that is commanded by the SID.eg 6000ft is quite common in the UK.Mark

[Guest]

Hi,I now hit the speed button (set to V2+15) after "wheels up" and let the plane climb to the AA prior to vnav arm, I do take off with Lnav armed. Vnav armed on the ground is dangerous as the thrust could be applied earlier than required and result in a very fast taxi around the airport.I normally have the speed restrictor in Vnav set to the max efficent cms which is about 220kts.Chris

[Guest Mark McG]

Chris,VNAV only becomes active when passing 400ft AGL.Taxiing around the airport, I have Autothrottle armed, and use manual throttle control to achieve taxi speeds.I have yet to see any of the excess thrust problems you describe.My Take Off Procedure is:Autothrottle Armed.VNAV Armed.Advance Throttle to 70%N1 Manually, letting engines stabilise.Select N1. This advances throttle to TO setting and engages Autothrottle.Rotate, Climb Out at V2+15, Gear Up on positive climb.Passing 400ft AGL VNAV Automatically kicks in, and starts feeding info to the flight director and autothrottle.Passing my first segment climb altitude ( acceleration height), I start retracting the flaps and increasing speed to 250 knots.Setting either CLB, CLB1 or CLB2 on the TMC as required.Normally passing about 10000ft I will switch on the autopilot.Initially I only use the MCP & FMC LNAV/VNAV to feed data to the Flight Director to allow me to hand fly the bird.Mark

[Guest wkzzo]

Mark thats my exact procedure also .Hand fly to 10k with the flight director on, lnav and vnav armed.

[Guest Mark McG]

Wallace,the only additional thing I do is set up the FMC with a VNAV climb restriction of V2+15 to 1500ft AGL, to simulate the V2+15 climb out procedures in many airlines SOP.Mark

[crvm]

This is a very good procedure indeed. And "Rotate, Climb Out at V2+15, Gear Up on positive climb". I think you forgot to mention that you always set V2 in the IAS/MACH window on the MCP with the F/D on for TO mode which gives you the correct pitchbar on the ADI to follow for V2 + 15 speed etc... Best Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"

[Guest Mark McG]

Randy,forgot to mention that.By using the hidden click spot on the ASI to set the Bugs, V2 is automatically set on the MCP.Mark

[crvm]

LOL, I did not know that hehe. Learn something new all the timeBest Wishes, Randy J. Smith [h3]" A little learning is a dangerous thing"[/h3]AMD XP 2100 |MUNCHKIN 512 DDR RAM |ECS[/b ][i] K7S5A MB[/i] |GF3 64 MEG |WIN XP PRO |MITSUBISHI DIAMOND PLUS 91 19"

[Guest ielchitz]

Randy,Isn't amazing how there is always something else to learn?I just wanted to add my thoughts that this all sounds similar to my procedures with a few changes:Once we pass the acceleration altitude, FLCH 220 is my choice for vertical mode in the climb to 10k where I bump up the speed 40-50 knots until I flip on the VNAV. Usually VNAV goes on soon before or after I go into CMD mode.Unless I am on a really complex departure I will use HDG SEL rather than LNAV until I am on course at which time I replot and engage.Can't remember the details - but I am sure it was Rob Hall who mentioned learning about the FLCH climb mode which I believe was an Air Canada thing - but then again my brain doesn't work too well sometimes .Ian Elchitz CYWG

[Guest CYOW_pilot]

Ian,My only comment would be that you should set the speed to 250, not 220 (if I interpreted your post correctly) for the climb to 10K. The only time Air Canada would climb at less than 250 is during the initial turn to the on-course IF the departure heading (runway heading or whatever) is more than 90 degrees from the outbound track. For example, departing RWY 31 at CYWG for an eastbound trip (to YYZ say), once noise abatement is complete hold Vzf (min clean manouevring speed) throughout the right turn until you are passing a heading of 353 (outbound heading of 083 to YHD minus 90 degrees)then lower the nose and acclerate to 250 (or more, no speed limit of 250 on departures in Canada except a certain airports).The reason for this is to minimize distance travelled in the direction away from your intended track and to convert that energy into altitude (speed is closer to best angle of climb).Finally, for the departure climb, it makes little difference whether you use FL CHG or VNAV (except you have to set the speed with FL CHG, the power setting will be the same and so will the speed if you set 250) so why not use VNAV. My 2 cents.Kevin in CYOW

[ACA857]

I heard my name mentioned ;-)The reason I was given for using FLCH on departure/climb was that it is a preferred method over using VNAV below 10,000 feet. As to flying 220kt (or thereabouts) climb speed up to 10,000 feet in FLCH, I was told the reason is to get up to/above 10,000 feet in less time, then they can lose the 250kt restriction in less time. This is all dependant on ATC restrictions, plot, weather, pilot's mood, etc, etc. Whether the above is all simply pilot preference or an airline standard I am not sure, but this came from a conversation with an ACA 767 f/o last November. The f/o told me he generally does not engage the A/P until around 10,000 feet, simply hand-fly's the FD...but on my 767 ride home from EGLL, the Capt. told me he engaged the A/P at about 1500 feet. Again, I suppose it depends on their mood, whether they got their salary increase, hot coffee, etc ;-) Tally ho.Rob.

[marcom]

" I suppose it depends on their mood"It really depends on a fancy term called "risk management". If there is a lot of traffic, or a high stress situation such as a complex departure or similar, you won't use handfly the plane. Instead, activate the AP and then you have a lot more ressources available to work on further tasks. On the other hand, when weather is CAVOK, everything's fine, no traffic, straight in approach with a 20 mile final, you can enjoy handflying the plane.RegardsMark