Two interview questions
 

I need some help with a couple of questions:

1. When will a compressor stall most likely occur?
2. What determines the most desirable cruise altitude for jet aircraft?

1. High AOA, low airspeed, high power
2. OAT

Sounds like a Republic interview is coming up huh?

1) In addition to what Joe said, a strong X-wind can be a factor.

2) Generally you want less-dense air (less drag), which always means higher altitudes. But the tradeoff is that it at takes a lot of gas to climb to higher altitude, so on a shorter flight it may not be economical to burn the gas to get to F390 only to have to immediately start your descent. Also high-altitude winds play an important role. You may better of at F290 with a 30 kt headwind than that at F390 with a 130 Kt headwind.

These are typical CRJ altitudes (westbound, no unusual wind):
15 min flight: 16,000
30 min flight: F240
1 hour flight: F320
> 1 hour flight: F380

I know you're not talking about the -200 in the last two...especially 380.:eek:

Getting filed at 320 -340 is not too unusual in the 200...sometimes you make it, sometimes you don't. 350+ is pretty much 700/900.

I never liked to take the -200 over 300 unless it was winter. Never flew the -900 but the 700 had no problem up high and was actually a nice ride.

Don't forget weight for #2, as you get lighter your best cruise altitude goes up.