D-TO (B737) ?
 

Hi guys...

Anyone knows what the D in "D-TO" stands for ?

It is just something that came up on a eqpt recurrent class...

Stands for Derate Take-off

Cheers

Depending on where you saw it it could be 'displaced' as in take-off point.

It appears on the TMD, whenever an Assumed Temperature is selected.

I believe that it doesn't stand for Derate, because when we do a DERATE, the TMD shows TO1 / TO2.

When a Derate is combined with an assumed temperature we have D-TO1 or D-TO2.

It's just for curiosity ! In case anyone knows, please share with us.

Our documentation doesn't say much else:

• TO – takeoff
• TO 1 – derated takeoff one
• TO 2 – derated takeoff two
• D-TO – assumed temperature reduced thrust takeoff
• D-TO 1 – derate one and assumed temperature reduced thrust takeoff
• D-TO 2 – derate two and assumed temperature reduced thrust takeoff

There are planes with different annunciations though:

• R-TO – reduced takeoff
• R-CLB – reduced climb

Note: R-TO does not indicate the type of reduced takeoff. The N1 limit may be reduced due to the entry of an assumed temperature, a takeoff thrust derate or a combination of both assumed temperature and takeoff thrust derate.

Can't speak specifically for the 737 but FWIW on the 777 and 747 "D-TO" was the correct annunciation when you were performing an assumed temperature take-off.

TO 1 or TO 2 was seen on the 744 when you performing a Reduced Thrust Take-off, something we'd (generally) only get involved with if performing a three engined ferry.

In any event surely the answer should all be in the appropriate FCOM 2.

( slow in typing - what Denti said!!)