Dear all,
while setting up the route i often get the message in the FMC saying that a certain speed cannot be achieve. How to solve this?
In this specific case, as you can see in the screenshot, from RUSME to OAKES i have 136 NM to go. So why the aircraft cannot reduce the speed to 280 KTS (as required by the STAR) once reach Oakes?
how would i need to set the FMC so that it matches the STAR?
Thanks for any feedback.
Too fast indicated airspeed for your altitude. It’s ok, you’ll just be a little slower at OAKES in indicated airspeed.
This is because the speed set on your DES page is lower than 280 kts. If you increase the transition speed from Mach to indicated to 280 kts or greater the airplane will comply with that speed restriction as planned on the CDU. It can only comply with the restriction if the airspeed selected on the DES page is higher or equal to the restriction set on LEGS page, the airplane will only decelerate or maintain the speed, it will not accelerate to a higher speed than the one selected on the DES page.
Thanks s lot for this information! Got it 
You’re still not going to hit 280 knots in this aircraft at FL320. Red tape.
If that’s a speed restriction, change it for 280B (280 or below). You input that by typing 280B/. Try not to delete the restriction as you cannot enter altitude restriction brackets in the 737 (FL240 FL320).
This is a method of avoiding the CDU message “UNABLE 280 KTS AT OAKES” from appearing, but as this is a STAR, specifically the OAKES2 into OAK if I’m not mistaken, that is a “hard” speed restriction (cross OAKES AT 280 kts and between FL320-FL240). This method would not comply with the STAR restriction if the descent speed is lower than 280 kts on the DES page and not adjusted.
I didn’t know it came from a STAR. In that case we’d override it during the cruise changing it to 280B or something and then put it back to 280/ during the brief before descent. This isn’t a common message to see (especially on descents) but we override “steep descent after XXXXX” messages all the time and then either correct it during briefing or ask ATC if they really need us to fly that.
