# How should I read these climb and descent profile notations?

I use a tool called SimBrief to build virtual flight plans for a desktop flight simulator. As I've been getting more familiar with procedures, I've also been exploring more advanced settings in the builder as well as some parts of the OFP output.

One thing that I can't figure out even after consulting the tool's docs is how ascent and descent profiles are represented: for example, for a 737-800 on a medium-haul route, one of the available ascent profiles will be 250/280/78, while one of the decent profiles is 78/280/280.

• My guess would be 250 to 10,000 ft; 280 from 10k to crossover altitude, then Mach .78 after. Crossover altitude for that scenario would be roughly FL 325. Mach.78 seems a little high for a climb Mach, but I don't fly the 737. Also, 280 in the descent profile below 10k doesn't work, so my guess may be far from right. Feb 28 '18 at 1:16
• I agree with @JWalters, although I wouldn’t say .78 is at all fast for a modern airliner’s climb profile. That’s about what the 737 NG uses, with some adjustments for head/tail wind (typically maybe +/- 20 kts and .02M, ballpark). Agree that I’d expect the last # in the descent profile to be 250 kts, not 280. Feb 28 '18 at 15:23
• @RalphJ That could well be; as I said, I don't fly the 737. The jets that I fly have a typical climb profile of 250 up to crossover then .62. Feb 28 '18 at 19:13