PIC 737 300 - Take off with TO/GA set

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Hi

 

When using the TO/GA function ('hidden' on the AP) I find that the acceleration to V1 and rotate is superb; but after about half a second following take off and climb, altitude is suddenly lost for a few seconds bringing disaster very close.  I am pretty sure this altitude drop is due to a loss of thrust after take off but I cannot be certain.

 

After a few seconds she regains speed and climbs as expected.  The physical throttle setting is set at full throughout.

 

Has anyone else experienced this?  Is there a way to improve my procedures? 

 

Thanks for reading this.

 

Best wishes

 

Mike