Clarification on Boeing EFB OPT
 

I have a question regarding Boeing EFB. When calculating takeoff performance and entering all required data, such as runway, temperature, QNH, etc. without inputting the takeoff weight, the EFB still generates a "TOGW."

Could someone clarify what exactly this TOGW? Is it representing the RTOW calculated based on the current conditions?

Basically yes. If you don't put a weight it'll tell you the max weight for those conditions.

RTOW is a maximum weight takeoff weight taking into account performance limited weights not only at takeoff, but also cruise (engine out terrain clearance) and landing performance (in dispatch).

The EFB TOGW is the maximum based on structural and performance limit for takeoff only.

Yeah, I’ve noticed the RTOW in the EFB never exceeds MTOW, regardless of the entered conditions. Does the EFB apply MTOW as a hard limit by default?

Ours do apply MTOW as a hard limit...

That seems fairly obvious since you can't legally go any higher.

Although it is useful to know what constraints you are operating under and what margins you have.

The engine derate will tell you the margin you have. Once the assumed temp reduces to ambient then the RTOW starts to drop.

Kind of, depending on if there are obstacles in the departure and where they are. It could be more to do with max continuous thrust (fixed) if the dominant obstacle is some distance away.

I find the weight margin, RTOW vs. ATOW, a better indicator of how close to the wire you actually are.