While I was outside Wednesday afternoon putting up holiday lights, I noticed an aircraft that was at cruising altitude (i.e. not an aircraft landing or taking off from my local airport) and it appeared to be much closer than your typical aircraft at fly-by altitude, such that you could see more detail of the aircraft than normal.
I pulled up flightaware and found out it was a Mesa Airlines CRJ flight from oklahoma city to los angeles lax and it was indeed flying at its planned maximum altitude of 24,000 feet at about 455 knots. Looking over the last few days of flights, most flights occurred 34,000 to 38,000 feet and took 10-15 minutes longer to fly than today’s flight.
It got me to wonder why that aircraft was flying so low for a cruising altitude when I notice most cruising altitudes of 34,000 to 40,000 feet as planes fly high over the city.
I assume if there was depressurization at takeoff, the plane would return to oklahoma city or at least not fly at 24,000 feet but at some lower altitude where oxygen is more plentiful while getting ready to land at an emergency airport. Other thought was maybe engine performance would be better at lower altitude where there is slightly more oxygen available to use in the combustion process. I’ve ruled out avoiding the jetstream reason as it doesn’t appear there was a jetstream at 300mb or 250mb that would cause headwinds.
Any ideas or common reasons why an aircraft planned altitude might be that low?