Go Around mode

[Rchrdsnjh1]

Hi guys, before we start i'm not a pilot, im an engineer so go easy. I have read lots of conflicting information on when a go around can be initiated i.e does the autoland have to be engaged? Do the flaps have to be at a certain position?

Also, if the autopilot has been engaged, does it stay engaged after initiation of go around? And if no other controls are touched, when does go around mode disengage? Does it disengage at 5000ft for example?

[Check Airman]

What kind of engineer are you? Which plane are you referring to? They're all different.

[Dash8driver1312]

On my type (DH8D), the procedure is:
Pilot (either one as necessity dictates) calls "go around"
Pilot flying pushes the TOGA button to automatically change the flight director to HEADING and PITCH mode, disconnects the autopilot if it was engaged, advances the power levers, pitches the nose smoothly up to an appropriate attitude, calls for flaps and gear to be set as appropriate by the assisting pilot.

The height you climb to and route flown depend on the airport and runway, but at the end of the sequence you would most likely be clean or first stage of flaps, at a set altitude, autopilot re-engaged, and planning on another approach shortly, a hold, or a diversion, depending on why you went around in the first place.

Much abridged and simplified, but I do wonder what you have heard and from whom.

[Intruder]

In general, Go Around (or TOGA -- TakeOff/Go Around) mode is armed or selected during takeoff and approach. As CA indicated, details vary among airplanes (e.g., Go Around may be automatically armed when Approach Logic is satisfied or when Approach mode is selected).

Flap or gear selection should not inhibit Go Around. If another mode (e.g., VNAV and/or LNAV) is armed when Go Around is selected, Go Around will transition to that mode when the appropriate conditions (e.g., altitude) are attained. Go Around can be done in either Autopilot or Flight Director mode, or with both turned off (since Go Around is also an AutoThrottle mode).

[safetypee]

In modern aircraft, TOGA is usually a combination of thrust and pitch control, but some installations allow independent operation.
After mode selection, a representative thrust level should be indicated on the primary power instruments or thrust management system, and with autothrottle engaged, this thrust level is achieved automatically. This is often referred to as ‘takeoff thrust’, but the mode of operation can be used for either takeoff or go around, not necessarily at the same thrust level.

The pitch mode is primarily speed referenced commanding attitude, but may involve some acceleration; the speed value is normally the climb (safety) or approach reference speed plus a bit, but the addition might be reduced with engine failure (alternative systems may use or mix angle of attack, and have stall protection).
The pitch reference attitude can be shown on the flight director for manual flight, and used by the autopilot if engaged.

For takeoff (TO), there is normally a requirement to be in the air and/or at a safe speed.
For go around (GA) selection, there may be an upper altitude limit and the need for an approach mode to be active (not necessarily autoland), but otherwise, depending on type/design, GA can be selected at any time until touchdown irrespective of flap setting.
Disengagement is usually by pilot selection to another mode or at some preselected altitude, to ALT mode.

[NSEU]

Flap or gear selection should not inhibit Go Around.

On the 747-400, flaps must be down (or the glideslope captured) for the Autopilot/Flight Director and Autothrottle "Go Around" mode to arm. Then it is up to you to activate it with a push of one of the TOGA switches on the thrust levers. Selecting different flaps afterwards should not affect the go-around.

If the Autopilot is not engaged, the plane will not fly itself up/down left/right. If the A/T switch is not armed, the thrust levers will not provide go-around thrust.

(EDIT) TO/GA mode will remain engaged until either you change the mode, or the aircraft reaches the altitude set in the Autopilot Mode Control Panel (although it is advisable to change pitch mode prior to that).

However, as stated before, it's all dependent on aircraft type.

[Rchrdsnjh1]

Thanks very much for the responses. The conflicting information i have read is probably down to differences between types of aircraft. The information in the 747 maintenance training manual states: "Go around mode is engaged when there are these conditions - 1, autothrottle armed. 2, airplane in the air. 3, glideslope captured or flaps not zero. 4, thrust limit mode not T/O.

So if i'm understanding this correctly, if all 4 conditions above are not met, go around can not be initiated?

[Rchrdsnjh1]

Another source of information on go-around mode is from a book- 'Automatic Flight Control' by Pallett. This states that go around mode can be engaged when rad alt is less than 2000ft and autothrottle is engaged. In the same paragraph he also states that a single press of the TOGA switch initiates a reduced thrust go around and a double press of TOGA initiates go around with full thrust rating.

Could any body shed any light on which particular type of aircraft he may be referring to, or is the information he gives fairly standard amongst the variants?

[Intruder]

A go-around can be initiated at any time. The difference is whether you will get automatic tracking or will have to hand-fly or use other autopilot modes to make the airplane do what you want it to do.

[BOAC]

Could any body shed any light - 737 certainly. However, as Int says, you can always do it the old fashioned way - pull back on the 'stick' and increase power.

[EW73]

And, in the 737NG at least, on a single autopilot approach, you will ALWAYS need to "pull back on the 'stick' and increase power" once TOGA has been initiated.
:E

[Rchrdsnjh1]

Thanks for the info people

[NSEU]

The information in the 747 maintenance training manual states: "Go around mode is engaged when there are these conditions - 1, autothrottle armed. 2, airplane in the air. 3, glideslope captured or flaps not zero. 4, thrust limit mode not T/O.

Resurrecting an old message thread...

I have been unable to find (in the 747-400 engineering manuals) any data paths from the Flap Control Units to the Flight Control Units which contain leading edge flap position information.... only inboard trailing edge flap position. Ref wiring schematic 27-51-04 Sh 2

How can the aircraft go into GA mode at Flaps 1 if LE Flap information is not available to the FMC? Similarly I only see inboard TE Flap data going to the FMC for thrust mode limit (G/A). The FMC generates the modes on EICAS.

Tech gurus?

Thanks
NSEU

[ManaAdaSystem]

And, in the 737NG at least, on a single autopilot approach, you will ALWAYS need to "pull back on the 'stick' and increase power" once TOGA has been initiated

No.
The autopilot will disconnect, but not the autothrottle. Thrust will take care of itself and the nose will come up nicely all by itself but you still need to fly the aircraft.
If you use manual throttles you need to increase thrust. I learned that on my first flight lesson. If I want to go up, I need to increase power/thrust, so no surprise there.

What annoys me on the NG is the automatic autopilot disconnect when on a single channel or non precision approach.
All other passenger aircraft I have flown have had automatic go around capability for all approach types.

[cf6-80c2b5f]

I have been unable to find (in the 747-400 engineering manuals) any data paths from the Flap Control Units to the Flight Control Units which contain leading edge flap position information.... only inboard trailing edge flap position. Ref wiring schematic 27-51-04 Sh 2Is this what you are looking for?

https://drive.google.com/file/d/0B-WRh0Hf7VdZaWNJc1B6NllSblE/view?usp=sharing

[NSEU]

Thanks, but that's just a repeat of what is shown in the wiring schematic (27-51-04 sh2).

Your picture is from the Wiring Diagram Manuals (WDMs). Wiring Diagram Manuals show the finer details of the wires connecting the computers, but often omit what data is being relayed on those wires. The System Schematic Manuals (SSMs) often show the data which is being relayed on the wires, but may omit the details of the wires.

According to the schematics, pins K14 and K15 only have inboard TE data on them.

Cheers
NSEU