737 NG windshear escape manoeuvre

[alosaurus]

Just over a year ago this question was asked.

"I refer to the Windshear Escape Maneuvre included in the Boeing 737 QRH NON-NORMAL MANEUVRES section.

If the maneuvre is flown MANUALLY (A/P and A/T OFF) with only F/D guidance available, Boeing say to aggressively apply maximum thrust whereas in the AUTOMATIC case either TOGA switch need to be pressed and verify thrust levers advance to GA power.

As we know by pressing the TOGAs once it will only give us a reduced goaround thrust so I assume Boeing wants us to push them twice, is that correct? "

Only one person answered the actual question .... his answer is partly supported by what happens in two of our simulators....and contradicted by what happens in the other two.

In non windshear conditions pressing TOGA once will command a 1000 to 2000 FPM GA.

A second press of TOGA will change the FMA annunciation to N1 and provide full go around thrust.

When a reactive (as opposed to predictive) windshear alert is engaged two sims annunciate N1 with one TOGA press...the other two require a second press of TOGA.

Just as the flight director annunciations are different when TOGA is pressed once in windshear conditions are the FMA thrust mode annunciations also not also different from a single non windshear press of a TOGA button.

I would expect one press of TOGA to provide BOTH FD commanding windshear escape guidance AND an FMA of N1 in Windshear conditions
(worst case scenario a loss of 15 knots of airspeed close to the ground is no place for a reduced thrust recovery).

[N1 Limit]

The procedure says press TOGA disconnect A/T and max thrust,the initial TOGA selection is to give you enough energy to depart from the windshear and thereafter once A/T is disconnected firewall the thrust levers

[RAT 5]

One thing to be aware of with TOGA is that to get max TOGA thrust you need to wait for the TMCP FMA to change before pressing the 2nd time. If you click twice too quickly you will not get the full whack, but be stuck in reduced.

[galdian]

Ready to be flamed but suggest the initial action (Press TOGA) has absolutely NOTHING to do with thrust - depending on the type annd stage of the approach the autothrottle may or may not respond to TOGA.

The one constant in ALL cases is that FD will set 15 degrees:
- normal takeoff presentation;
- setting that will be followed if in automatics AND ESCAPE PERFORMANCE IS SATISFACTORY and so only have to monitor;
- INITIAL manual Go Around setting which is then ignored if additional escape performance is required.

Obtaining Go Around thrust after pressing TOGA is a bonus, NOT the objective.

Cheers.

[BOAC]

Referring to nnm 1.10 of the 737 QRH, galdian, I read that, as with a single engine TOGA press, with a 'windshear' warning the logic will deliver full g/a thrust on press. In any case, reading 1.10, it does not matter since both PF and PNF are required to 'Verify thrust advances to g/a power"/'Assure maximum thrust'. If the memory items there are followed correctly it really matters not what happens inside a computer chip. The old adage of "If it is not doing what you want, disconnect and be a pilot" applies as always.

As to why alosaurus's sims are producing conflicting results, I know not. Something for the manufacturers?

[de facto]

and thereafter once A/T is disconnected firewall the thrust levers

And why would you do that 'N1 limit'?? Except burning your own a:mad::mad: