I flew into OKC last night and received a 250./10000 at DECKK from ATC. After punching into the CDU, I received a "Unable 250 at DECKK" message. I was only flying at 285 knots indicated and had 95 miles to DECKK at 32,000. Additionally, winds were a near 96 knot head wind at 289 degrees. It seemed to me that making both the altitude and speed restriction should have been easy via VNAV. I took a look at the DES page and did not see DECKK listed as I normally do and was unable to enter the fix and speed/altitude restriction. I ended uop using FLCH rather than VNAV to meet the restriction.I guess my question are why DECKK did not show in the descent page? What are the circumstances for a descent fix to appear in the DES page?Thanks

If your route expected to be below 10,000/250 before DECKK then the message would indicate that you can't go back up to it. The waypoint that showed up on your DES page was the next crossing restriction from your legs page. Next time, try entering the restriction as 250B/10000B or make sure no earlier restriction would force you to climb or accelerate.

I was above DECKK 95 miles out at 32,000 feet. DECKK was the next fix with a restriction in the legs page. I expected to see DECKK int he DES page.

I was above DECKK 95 miles out at 32,000 feet. DECKK was the next fix with a restriction in the legs page. I expected to see DECKK int he DES page.

What did you see instead?

The descent page had no fix. It was blank.

It probably yelled at you because it wanted to go 240 under 10,000. It'll automatically restrict itself under 10,000, so you don't need to set the 250 knot restriction. It's already accounted for it. Take a look at your descent page for the speed restriction setting (I believe that's where it is - I'm not looking at it at the moment). It'll probably say 240/10000.

That's interesting. I think I will test that. Makes sense but I would still expect to see the Fix name the in the descent page. I guess if you were given a speed of more than 240 at 10,000, you would need to clear the global 240 knot restriction?

That's interesting. I think I will test that. Makes sense but I would still expect to see the Fix name the in the descent page. I guess if you were given a speed of more than 240 at 10,000, you would need to clear the global 240 knot restriction?

In the United States, you're never going to get ATC telling you to fly faster than 250 under 10. It's allowed in certain circumstances (minimum safe clean speed, by FAA Admin waiver, and so on), but it is never prompted by ATC. I believe in Canada, they can waive the restriction, but ATC still can't request higher than the speed limit.As far as the FIX showing up in the descent page, it probably only allows a fully validated fix to show there. Had you only entered /10000 and let it take care of the speed (would likely show up on the legs page as 240/10000), it would have shown up as a "next restriction" fix.

Kyle, I am not sure about FAA, but under JAA, some types of airspace, namely A, B, and C, IIRC, are extempt from 250/FL100 rule. Also, ATC may ask for, or grant pilots request for, high speed. There are several reasons for this rule, but at times, those are moot, and lifting the restriction can aid the fuel economy.My personal "SOP" is: maximum 250kts on climb out, or 240kts on descend under FL100, unlessa)higher speed mandated by arrival or departure procedure, orb)ATC approves high speed explicitely on departure, orc)ATC requires high speed explicitely on arrival, ord)minimum clean speed is more than either 250kts or 240kts for departure and arrival, respectivelywith addendum that (in cases a-c) PF may decline to use speeds higher than 250kts

Who said anythin

In the United States, you're never going to get ATC telling you to fly faster than 250 under 10. It's allowed in certain circumstances (minimum safe clean speed, by FAA Admin waiver, and so on), but it is never prompted by ATC. I believe in Canada, they can waive the restriction, but ATC still can't request higher than the speed limit.As far as the FIX showing up in the descent page, it probably only allows a fully validated fix to show there. Had you only entered /10000 and let it take care of the speed (would likely show up on the legs page as 240/10000), it would have shown up as a "next restriction" fix.

Kyle, I am not sure about FAA, but under JAA, some types of airspace, namely A, B, and C, IIRC, are extempt from 250/FL100 rule. Also, ATC may ask for, or grant pilots request for, high speed. There are several reasons for this rule, but at times, those are moot, and lifting the restriction can aid the fuel economy.My personal "SOP" is: maximum 250kts on climb out, or 240kts on descend under FL100, unlessa)higher speed mandated by arrival or departure procedure, orb)ATC approves high speed explicitely on departure, orc)ATC requires high speed explicitely on arrival, ord)minimum clean speed is more than either 250kts or 240kts for departure and arrival, respectivelywith addendum that (in cases a-c) PF may decline to use speeds higher than 250kts

Who said anything about faster than 250 Knots below 10,000? We were talking about the difference between 250 in the legs page and how that might react with the 240/10000 knot restriction in another page, I think descent.

Who said anythinWho said anything about faster than 250 Knots below 10,000? We were talking about the difference between 250 in the legs page and how that might react with the 240/10000 knot restriction in another page, I think descent.

They will conflict.

I think you guys just cleared up an unanswered question I have sometimes on my arrivals into LAX. I get the same thing, ane now i think it is because my aircraft is already knowing it will be slower...lol.

Who said anything about faster than 250 Knots below 10,000? We were talking about the difference between 250 in the legs page and how that might react with the 240/10000 knot restriction in another page, I think descent.

You alluded to it:

I guess if you were given a speed of more than 240 at 10,000, you would need to clear the global 240 knot restriction?

...so I addressed the comment related to the likelihood you'd ever be given a speed more than that. As far as ATC goes, most aircraft will be using 240 under 10 (the automation generally commands 240 to add in a buffer, and most pilots do just about the same). In the end, if ATC says cross OJAAY at 250/10000, and the automation aims for 240, it's fine.No need to clear the 240/10000 restriction on the other page. Just add the /10000 to the LEGS page and the plane will take care of the speed restriction.

The error is because you're trying to violate the global 240/10000 restriction on the DES page. You will not see a fix name because it's ignoring that. If you want to actually do 250 at 10000, you have two options:1. Change the global restriction to 250/10000.2. Use Speed Intervention to force 250.

Great info!From.the time I have read this, I took.heed, and have made 3 flights now into KLAX without the FMC yelling at me.Good stuff....I was always just pushing 250, when like stated above it was trying for 240.