AT speed after take off

[Peter de Bruin 0]

I would like to fly at least the SID’s by hand instead of LNAV-VNAV/ CMD in order to get more feeling with this new bird. However when I take-off, N1 mode remains in control and drives this bird into overspeed and behind. I made all the necessary arrangements for a normal take off like in the tutorial ( EGKK-EHAM). So we go, roll and engage the TO mode with Flaps 5 selected. The PFD showes in white “armed” and switches then to green “TO armed” mode on the right and “N1” on the left of the PFD display. As I get too fast and to high very soon I would like to pitch over and take trust away by pressing SPEED (selected 220 knts on MCP ) The speed knobs does not react, Oh boy! Let’s try pressing the N1 knob then. The green light disappears but N1 trust remains ! The only thing I am able to do to stop this full force from the engines is flicking the AT switch off and take the levers to say around 60 percent trust and level off. However I would like the help of the AT and engage the AT switch again and press SPEED but NOT a THING. How should I fly by hand after Take-off with the help of the AutoTrottle be done, as I don’t get it. With the old PMDG737-600 (fs9) I could select speed and the AT controlled my speed as selected in the MCP while I took care of height flying through the curves of the SID. Seems I need to learn a few new tricks with NGX? Thanks.

[Cristi_Neagu 134]

I actually found it pretty hard to keep straight and level using the AT. If i would pitch up slightly, the AT adds power and i start climbing like a bat out of hell. When I'm on departure and want to fly level, I turn AT off. When I'm ready to continue climbing, I engage the AT and let VNAV handle the thrust while I follow the FD cues.

[Jetman67 517]

that is interesting I have done many manuals sids, after lift off I pitch to the take of attitude on the FD to maintain v2+20 whilst raising the gear then I select VNAV and LNAV to follow the FD bars for a manual SID, I am able to maintain the nominal climb out speed until the acceleration phase at flap retraction, I am pretty sure the AT is on N1 I will have to try again to be sure

[Jetman67 517]

my N1 speeds are commanded by the FMC as I see the purple speed bug that the N1 is referencing, if the FMC is set up correctly then N1 should command this speed as a reference if not you should be able to use AT with the speed button not sure why that is not engaging

[Tabs 2,790]

Exactly as Jason says - you're still in TO/GA mode. You need to select N1, LVL CHG, or VNAV to get the A/T out of TO/GA or else disconnect the A/T and control thrust manually as well.You can still handfly in LNAV and VNAV - the flight director and the autopilot are two separate systems.

[Peter de Bruin 0]

My Acceleration Height is 1500ft in the FMC take-off page and have AT override by levers “”NEVER”” in the FMC state selected for your info. Also did not select VNAV or LNAV while departing and CMD is OFF as well. The FMC is programmed with the SID with realistic speeds and heights like 220/7000ft for reference in the Navigational Display. Take-off mode engaged during the roll and we depart at V2 with indication ARM ( white ) which went to Green N1 and TO/GA in PFD when selecting TO during the roll. Got a THR Hold indication after 80 knts and TO/GA remains green. Rotation with 99 percent N1 – 147knts from EDDM elevation height 1500ft / rw08R for LOWI via TULS9Q SID - at some point during climb out the N1 green indicator disappeared and got a white arm indication instead - Then engines go from 99 to 93 percent while N1 green comes up again while we climb out at some 170 knts - 3000ft/min. As I do not want to climb higher then 7000ft, would like to level out by pressing SPEED / did meanwhile increase the window from 162 during take-off into 220 for the SID waypoints to Tulsi via Munich VOR. . Its then that I want but do not get SPEED activated ! My second action then involves flicking AT off and ON again hoping to activate SPEED ( kind of reset was my first thought ) but this does not work either ! The Speed knob remains black.... My third option which remains I guessed is to De-activate AT and drive the levers back to 60 percent by hand in order to get control over the speed increasing while levelling off. – Do not get SPEED to work at all. Maybe this short description helps a bit in finding why SPEED cannot be activated, thanks for all the positive reponsse so far as I found it very comfortable in the earlier PMG737 to use SPEED during the departure flight after the initial climb, especially during those low level SID like the one in the tutorial in the UK.

[Jetman67 517]

hmmm this is intriguing, i will try this as soon as possible and let you know if i have the same issue

[HiFly 16]

Setting AT override to "NEVER" prevents you from speed intervention with AT armed. Choose another setting in the SETUP. If I remember right, there are actually three choices. Don't choose "ALWAYS" but choose the other one. I don't have the FMC up so I don't remember what it is called but it is the selection recommended, I believe, in the Introduction manual. Then you will be able to select SPD INTV once you are out of TKOF mode and use AT to manage the speed you select.

[Richard99_Photography 2]

Hello, I have the same problem. At reduction thrust altitude magenta pitch bar lowers and I follow it to increase speed, then retract flaps as scheduled by bugs. At that moment I am still on manual mode (A/T and FD ON, VNAV-LNAV-CMD OFF), N1 thrust is the same as for t/o and the thrust mode is CLB (as given by EICAS). Unfortunately IAS speed continue to increase, magenta pitch bar on PFD does not drive me to nose up (to reduce speed).So, what should I do? Pushing SPEED button and setting the desidered speed in MCP? I would like to maintain A/T ON and adjust speed by pitch, following the FD.Thanks. Bye.

[davidz 26]

Setting AT override to "NEVER" prevents you from speed intervention with AT armed. Choose another setting in the SETUP. If I remember right, there are actually three choices. Don't choose "ALWAYS" but choose the other one. I don't have the FMC up so I don't remember what it is called but it is the selection recommended, I believe, in the Introduction manual. Then you will be able to select SPD INTV once you are out of TKOF mode and use AT to manage the speed you select.

A/T override has nothing to do with SPD INTV. The A/T override allows you to use your joystick/physical throttles to override the A/T. For most people with non-motorised throttles, this is best used in the ONLY IN ARM mode as this allows you to control power when the A/T is not active.

Hello, I have the same problem. At reduction thrust altitude magenta pitch bar lowers and I follow it to increase speed, then retract flaps as scheduled by bugs. At that moment I am still on manual mode (A/T and FD ON, VNAV-LNAV-CMD OFF), N1 thrust is the same as for t/o and the thrust mode is CLB (as given by EICAS). Unfortunately IAS speed continue to increase, magenta pitch bar on PFD does not drive me to nose up (to reduce speed).So, what should I do? Pushing SPEED button and setting the desidered speed in MCP? I would like to maintain A/T ON and adjust speed by pitch, following the FD.Thanks. Bye.

You need to select a vertical mode such as VNAV or FLCH. Lowering the pitch with climb power set will definitely cause you to overspeed.

I actually found it pretty hard to keep straight and level using the AT. If i would pitch up slightly, the AT adds power and i start climbing like a bat out of hell. When I'm on departure and want to fly level, I turn AT off. When I'm ready to continue climbing, I engage the AT and let VNAV handle the thrust while I follow the FD cues.

Many pilots do not use autothrottle while hand-flying due to this problem. This happens in most aircraft, from Cessna 150s to Boeing 747s. An increase in power will generally cause an increase in pitch and vice versa. With the autothrottle off, you can judge this and compensate. With the autothrottle on, the system will increase and decrease power to maintain speed and will affect your ability to accurately fly an attitude.

[Peter de Bruin 0]

As suggested changed the Setting AT override from "NEVER" to “Hold/Arm” and did the take-off as described earlier. It didn’t make any difference – I am able to move the levers back to say 60 percent indicated by a blue line at the 4000 ft level off height but AT remains activated at N1. Also pressing the Speed knob, it doesn’t become engaged. The N1 light remains ON and we fly way out of speed limits soon if I do not flick the AT switch to OFF and take over trust by hand. Engaging AT into speed mode with speed bug at 220 is still impossible although we fly at a certain moment 220 at 4000 by hand !

[Scott434 12]

While performing a TOGA takeoff, what exactly triggers the switch from TO to CLB thrust mode? Is it the altitude you set for "Reduction" (pg 2 of Takeoff page) only? I am setting Reduction to 3500 but thrust is still being set to CLB at approx 1500 in spite of the Reduction setting. I assume I am missing something. My scenario is a simple hop from CYYJ to CYVR with a quick cruise altitude of 3500 ft. FMC flight plan is all good everything works (speeds and altitudes). What I want to do is takeoff with reduced thrust (0 pax, 0 cargo), fly the FD (not CMD), with vnav and lnav engaged until 3500 at which point I would like to retract flaps and carry on. I have set the cruise altitude to 3500. What ends up happening is in my takeoff and climb to 3500, it switches CLB-2 at around 1500 which causes an under speed condition (yellow box on speed tape). This behavior is with the "Reduction" height set to 3500 (pg 2 of Takeoff page). Been at it for quite some time now so it time to ask those who know. Thanks for the help.

[Peter de Bruin 0]

Thanks for the respons Scott but in my case the TO mode N1 remains although I get some reduced trust from 98 to 92 percent at around 3000ft. If I would like to go into AT / MCP selected speed at say 4000ft by pressing the speed button it doesn’t work. However I found this evening that unselecting N1 ( by pressing this N1 knob which has a green light which turns into black ), then pressing fletch and quickly pressing the speed knob will command MCP selected speed mode. ( speed knob goes green / at PFD got mcp select message instead of TO) This all while the AT switch remains ON. Better be quick after FLCH as otherwise we get full trust when flight change mode come in. So as I do not want to dwell to much away from my original question I would like to repeat why does MCP selected speed does not activate when the speed knob is pressed after take-off at reasonable height. Having in mind older PMDG737 and 747 (fs9) but also Level-D 767 (fsx) and PIC737 (fsx) the method works.

[HiFly 16]

Did you try pressing SPD INTV button first. That should make ASI display active and from then you can adjust speed using SPD button. I have not tried this while still in TKOF mode but it works once you are in N1 climb. I honestly can't remember if there is a minimum altitude that is required for this to work. I usually preset Vnav before takeoff and it will keep my ASI display blank. If I try to press SPD button at this point nothing happens. Once I press SPD INTV button, however, I am able to set my own speed in the ASI and if I have AP engaged then it will adjust my pitch to maintain that ASI. I can only assume that it will work for you the same way even if you don't have Vnav activated but I think you will have to be out of TKOF mode and into N1 climb mode before it will respond. Now if you adjust the speed setting in ASI while in N1 climbout the aircraft will not reduce the power setting, it will instead command a higher pitch ( or automatically pitch up if AP is engaged ) to maintain whatever speed you have input. If you try to reduce the pitch manually or using VSI without first setting a speed in the ASI (SPD INTV then ASI as I explained) it will cause an overspeed as the power setting will remain at N1 unless you manually reduce it at the same time as you reduce climb rate.

[HiFly 16]

An after thought, Peter. If your purpose is just to "pilot" the SID yourself but use autopilot, you can still use Vnav to climb to initial departure altitude and 240K. Once plane levels off, choose ALT HOLD and the ASI window will become active and display your FMC speed setting and you will be able to change it to your liking. You can then use SPD display to control speed, HDG SELECT to track the course and FLCH to climb to new altitudes ( or 1000 fpm VSI for small altitude increments.) If your initial speed to follow the SID is restricted to less than 240K then just set that restriction into your first waypoint and continue with Vnav until you reach that first altitude. The AP will only accelerate to that speed until you cross the waypoint. Then just select ALT HOLD and you are out of Vnav.