I should now the asnwer to this already but I want to make sure. You are in a modern Boeing doing a derated thrust takeoff. After selecting TOGA, you see THR REF displayed on your FMA. Soon after liftoff you encounter a windshear and desire maximum available thrust to escape the windshear. To achieve this, you can press TOGA again and now you will have full rated takeoff thrust.
quoting initial "jazmmedstab" post and I'll be giving B 777 description.
If aircraft is detecting windshear with associated warnings ,you MUST press TOGA switches so as to activate windshear followup by flight director.
Thrust status will change from THR REF to THR .
As someone said THR REF is just the reference thrust commanded by FMS ( D-TO, CLB etc)
Per exemple in approach , as flaps are non 0 ang glide slope captured thrust reference changes to G/A ( indicated top left of EICAS) and you autothrottle in SPEED mode on your FMA .
If you then press TOGA switches to make a go around, you will have a FMA change to THR REF wich means your airplane in is go around mode , THR REF meaning in this case: engine thrust is just thrust to acheive 2000 ft/mn rate of climb (if just one click on TOGA switch) . If you press a second time on toga switches , you then have your reference thrust changed to full goaround engine thrust .
Regarding thrust situation awareness , my eyes scan goes from FMA of course ,to EICAS green thrust indication . This particuraly on engine failure until CON is selected
pause !
Refering to some post speaking of TOGA control law :
Whatever take off or goaround mode, indeed, when altitude rate is greater than 1200 ft/mn, elevator controls pitch to keep selected speed.
When altitude rate becommes negative, aircraft is controlledby pitch.
When rate is between 0 and 1200 ft/mn, there is a combination of speed control and pitch control. Kind of small difference if autopilot used 600 ft/mn replacing 1200 value to be simple !
Happy new year.
Last edited by VNAV PATH; 31st Dec 2013 at 08:07.