Ok I've been reading that pilots almost always use VNAV on climb out to protect airspeed. So when you are following restrictions in a SID and ATC clears you to a higher altitude I suppose you have four choices (technically 5, I guess you could say "unable") 1. Continue to the cleared altitude with the restrictions (however ATC may want you higher now).2. Adjust altitude and airspeed with the FMC3. Use VS4. Use LVL CHG Of 3 or 4 I imagine 4 is best for airspeed protection. For 2, it works but you have to do some math to out guess getting the message; unable next altitude. What usually happens in the cockpit in this situation? Thanks,Doug Wilson

When in VNAV mode, just dial the new altitude into the MCP, hit Alt intervention and the aircraft will climb to the new Alt but still sticking to speed restrictions for each leg.

Simple. Thanks.

Also depends on how you were given your clearance. Let's say one of the points is DIXIE and the SID said at or below 10000ft. If the controller cleared you the SID and told you to climb and maintain 15,000, you should still honor the at or below 10,000. In that case VNAV and set 15,000ft. The plane will cross DIXIE at 10000ft. If he tells you to cross at 15,000, he modifies the SID. But if he turns you off the SID and clears you to 15000, up you go.If he amends your SID you are good to go. If not, you should meet your restrictions on the way up to the altitude he gives you. People bust SID restrictions at KTEB all the time, so much that the FAA requires this scenario in your refresher sims. The SID keeps you below a arrival route, but plenty people have climbed through it thinking that they were cleared to a higher altitude disregarded the SID restriction.

That makes perfect sense. Thank you. Doug Wilson

In the uk the phrase "climb NOW flight level xxx" means ignore any restrictions on the Sid and just climb direct to new cleared level.And as explained you would just select the new level on mcp and hit alt intervention...you may sometimes need to click this multiple times. You can also select delete and then the right lsk next to restriction which will delete it, would also delete any speed restriction there but wouldn't delete the 240 below 100 as that programmed in separately so generally save on most SIDS. Atc will also give no atc speed restriction often also allowing you to accelerate early.