I have noticed that the "bouncing" issue with the 777 when reducing thrust in the climb has been resolved......but it appears that there is still an issue with this shortly after take off if the autopilot is engaged and the speed does not quite match. Has anyone else noticed that?

Have to test it Christopher.

I've been making some really pleasing flights with the PMDG 777, but I use to fly the departure manually up to transition alt. Have to try engaging the AP sooner to check that !

Does anyone else get a sudden excessive nose up right after retracting the gear?

4 hours ago, Christopher Low said:

I have noticed that the "bouncing" issue with the 777 when reducing thrust in the climb has been resolved......but it appears that there is still an issue with this shortly after take off if the autopilot is engaged and the speed does not quite match. Has anyone else noticed that?

Could you elaborate on the issue? For example, at what stage (alt) do you engage the A/P, at what speed, and where is the speed bug set? 

• I engage the autopilot at around 500 feet (when THR REF appears on the MFA)

• v2 is 155 knots, and I set the speed on the MCP to 175 knots using Speed Intervention

EDIT: Rick also brings up an interesting point. There is a lot of chatter about that "pitch up" shortly after take off. I have noticed it, but it is not too excessive.

Edited Wednesday at 08:24 PM2 days by Christopher Low

1 hour ago, rick celik said:

Does anyone else get a sudden excessive nose up right after retracting the gear?

Yes! I find that when rotating, I get a steady rotate to 10 degrees and then it suddenly pulls very quickly back past 15 degrees

The 777 can easily exceed the v2 speed on rotation, which means that the IAS gets higher than the speed setting on the MCP after the wheels leave the ground. I assume that the pitch up is to get the speed back down to v2, but should it be doing that before it switches to THR REF mode?

46 minutes ago, Christopher Low said:

• I engage the autopilot at around 500 feet (when THR REF appears on the MFA)

• v2 is 155 knots, and I set the speed on the MCP to 175 knots using Speed Intervention

EDIT: Rick also brings up an interesting point. There is a lot of chatter about that "pitch up" shortly after take off. I have noticed it, but it is not too excessive.

Unfortunately, I don't find the PMDG 777's flying characteristics and flight-control behavior particularly convincing. This has been an issue, in my opinion, since the aircraft was first developed for the various simulators, including P3D, and some of the same characteristics appear to have been carried over into the current version. The overall result does not closely resemble the way the real 777 flies.

For example, the 777 does not simply "pitch up" shortly after takeoff, nor does it rotate to around 10° and then suddenly pitch rapidly through 15°, as mentioned by @BWBriscoe. The actual rotation and subsequent pitch response are much smoother and more progressive. The airplane establishes the commanded flight path in a controlled, steady manner rather than producing that abrupt pitch change.

I'll run your scenario and report back with what I observe.

Regarding the speed window, there is another important point. Once you open the MCP speed window during a VNAV departure, you are intervening in the VNAV speed management rather than simply continuing to follow the programmed takeoff profile. The resulting pitch response depends on the relationship between the airplane's current speed, the selected speed, and the phase of the climb.

For example, if the airplane is below 175 kt and you open the speed window and select 175 kt, the airplane will lower the nose as necessary to accelerate toward the selected speed. Conversely, if the airplane is already above 175 kt when you intervene and select 175 kt, the airplane will increase pitch to decelerate toward the selected target.

That behavior is quite different from the airplane simply "pitching up" or "pitching down" arbitrarily—the flight-control system is responding to the selected speed target.

1 hour ago, rick celik said:

Does anyone else get a sudden excessive nose up right after retracting the gear?

Sorry, no, nothing like that in the real airplane.

Sorry for the sacrilege and using AI, but I couldn't test it in the sim tonight, and I rushed looking for sources.

Some 10 years ago I would be reaching a couple fellow pilots, and asking for aircraft manuals, or searching on those I owned for various airliners :-) but these days Gemini, Copilot and the like are so so so at hand...

==== by Gemini ====

Yes, the Flight Director (FD) should absolutely be providing pitch guidance immediately after liftoff, which occurs while the autothrottle is still in HOLD mode, long before it switches back to a thrust reference mode. However, your assumption about the target speed needs a slight correction: the aircraft is not trying to pitch up to bring the speed back down to V₂, but rather to a target of V₂ + 15 knots.

The takeoff logic of the Boeing 777 governs this behavior through specific phase-dependent rules:

1. Target Speed Guidance Logic (TO/GA Pitch Mode)

Once the wheels leave the ground, the Flight Director enters active TO/GA pitch guidance. It guides the pilot (or autopilot) to maintain an initial target climb speed based on your actual performance:

• The Default Target: The system initially targets V₂ + 15 knots (or the airspeed at rotation plus 15 knots, whichever is greater).

• The Overspeed Buffer: If you rotate slowly or have immense excess thrust (common in a light 777) and your airspeed exceeds this initial target for more than 5 seconds, the system automatically recalculates and resets the target speed to your current airspeed, up to a maximum cap of V₂ + 25 knots.

If your speed climbs beyond V₂ + 25 knots due to over-rotation or excessive acceleration, the FD bars will command an aggressive pitch-up to trade that excess kinetic energy for altitude and bring the speed back down to the V₂ + 25 knot ceiling.

2. The Autothrottle Status Sequence

The reason this pitch correction happens before any mode changes is due to how the autothrottle operates during takeoff:

Phase	Autothrottle Mode	AFDS Pitch Mode	Behavior
Takeoff Roll (<80 kts)	THR REF	TO/GA	Throttles advance to the calculated takeoff thrust limit.
Takeoff Roll (>80 kts) to Liftoff	HOLD	TO/GA	Throttles lock in place so they don't roll back if an engine gets blocked or suffers an ephemeral fault.
Initial Climb (Liftoff to 400+ feet)	HOLD	TO/GA	Pitch controls airspeed. The engines are locked at takeoff thrust (HOLD), so the only way the aircraft can manage its speed is by adjusting the nose pitch.
Climb Phase (>400 feet / Acceleration Height)	THR REF or SPD	VNAV SPD or FLCH	The autothrottle wakes back up. Pitch shifts to following a path/climb profile, and the autothrottle takes over speed management.

Because the autothrottle is completely inert in HOLD mode right after liftoff, the aircraft must use pitch as its sole tool to control airspeed. If it didn't pitch up immediately to arrest the speed build-up, the airplane would rapidly accelerate past its flap placard speeds while climbing inefficiently.

Edited Wednesday at 09:16 PM2 days by jcomm

@Christopher Low, I checked the takeoff sequence, and everything is correct.

As I mentioned, when the airplane is below the selected 175-knot target and speed intervention is selected, the AFDS will adjust pitch as necessary to accelerate toward the MCP-selected speed. Conversely, if the airplane is already above 175 knots when speed intervention is selected and 175 knots is set on the MCP, the AFDS will increase pitch as necessary to decelerate toward the selected target.

The important point is that selecting speed intervention overrides the FMC-computed VNAV speed target. In this case, the normal VNAV acceleration schedule is no longer controlling the airplane; the AFDS follows the MCP-selected speed instead.

Therefore, if we select 175 knots during the climb, the airplane will remain at that selected speed rather than continuing with the programmed VNAV acceleration schedule. To return to FMC/VNAV speed management and allow the normal acceleration profile to resume, we need to deselect speed intervention by pushing the MCP IAS/MACH selector again.

I prefer to select the speed myself. However, it is not the pitching up or pitching down that bothers me. It is the "bouncing" that occurs sometimes when I do this. I do not believe that the 777 (or any airliner for that matter) should "bounce" up and down quickly at any time, particularly in calm conditions with a wind speed of 1m/s, and zero gusts.

I generally increase the speed to 200 knots during the climb when I pass through 2500 feet. The aircraft pitches forward to accommodate this. Perfectly normal.

In short, I have my own way of doing things, but the aircraft should still behave in a manner that obeys the laws of physics!

Edited yesterday at 09:21 AM1 day by Christopher Low

45 minutes ago, Christopher Low said:

However, it is not the pitching up or pitching down that bothers me. It is the "bouncing" that occurs sometimes when I do this. I do not believe that the 777 (or any airliner for that matter) should "bounce" up and down quickly at any time, particularly in calm conditions with a wind speed of 1m/s, and zero gusts.

Hey Chris, just to clarify the "bouncing" effect you are seeing on takeoff, which you describe as being different to expected pitch changes during climb, are you seeing small decreases in altitude then in addition to any pitch adjustments the aircraft is making? I am trying to visualize what you are seeing ?

The PMDG 777 exhibited this problem at the top of a climb relatively recently. This was identified as a bug, and it has been rectified. Unfortunately, it seems to be doing the same thing now and again just after take off when I select the autopilot. This occurs when the actual speed does not quite match the speed setting on the MCP. When I say "bounce", I mean that the nose pitches up and down very rapidly until it gradually smooths out and fades away. This kind of behaviour is totally unrealistic. It just would not happen in a huge airliner due to inertia.

Think of the way a rocking horse moves back and forth. Would you expect a Boeing 777 to exhibit that kind of motion?

Edited yesterday at 11:12 AM1 day by Christopher Low

The excessive pitch up is not an autopilot issue but a flight control issue as I haven't even set the AP, just manually pitching to 15 degrees.